Toyota Landcruiser (60 series) diesel stutter / judder under load uphill

By telleropnul, July 27, 2018

Wear gloves – diesel is a nasty fuel that irritates the skin.  Don’t wipe your hands on your clothing, don’t touch your face.  Keep an old cloth rag handy to wipe your hands (frequently).

 

DAY 1

A diesel engine is different from a petrol engine in a number of ways. Most importantly, diesel fuel is not ‘ignited’ by a spark plug; instead it is ignited by spontaneous combustion using high pressure.  A diesel engine block is extremely solid and able to withstand high internal pressure.  The piston moves up and down similar to a petrol car engine, but the compression of the fuel is much higher (20:1) compared to a petrol engine (10:1).  Because of a diesel engine running at much higher compression, fuel needs to be squirted into the cylinders at a high pressure.  I mean, howe else would you get fuel in there, right?  The piston further compressing the fuel/air mixture during its compression stroke.  This will cause the fuel/air mixture to combust.  There are no spark plugs to ignite the fuel/air mixture in the cylinder.  There are no valves, no cam shaft, no carburator; just a fuel injector that squirts fuel into each cylinder at exactly the right time; it just works.

Injecting fuel at high pressure introduces a number of challenges:

  • Diesel engines need a heavy duty car battery.  In a high combustion diesel engine the starter motor works a lot harder than in a petrol car.  Glow plugs that pre-heat the combustion chambers in the cyclinders when the engine is started cold require a lot of current.  Most start / battery problems occur in cold weather.
  • Injectors can inject liquid only.  Air and water in your fuel will stall the engine.  This is a big thing for diesel engines and a likely cause of problems.  So if your engine misfires or stalls, it is often a problem with your fuel line.

Troubleshooting diesel fuel line

Regardless of whether it is a clogged fuel filter or air being sucked into the fuel line somewhere, the process is the same.  For fuel in a diesel car to make its way from the fuel tank to the engine, it passes through a number of stages:

Main fuel line
Fuel tank
20cm of rubber fuel line
Stainless steel fuel line
10cm of rubber fuel line
Water trap
10cm of rubber fuel line
Stainless steel fuel line
20cm of rubber fuel line
Inline primary fuel filter
Lift pump (also called manual primer pump)
Bleed screw (also called bleeder valve)
Secondary fuel filter
Injector pump
Injectors

As the injector pump pumps more fuel than the injectors can process, excess fuel is returned to the fuel tank in a closed loop:

Return fuel line
Injectors are interconnected with stainless steel fuel line.
20cm of rubber fuel line connected to first injector.
Stainless steel return fuel line under vehicle.
30cm of rubber fuel line.
Fuel tank return line.

Evaporation / breather
There are a 4 breather hoses connected from the fuel tank to a plastic ‘octopus’ gooseneck in the rear side wall near the filler cap.  From the top of the gooseneck a breaher hose connects to a small filter that acts as a valve to prevent dirt to enter.  From here the line runs underneath the vehicle where it loops back underneath a chassis crossbeam somewhere near the water trap.  Some people purchase a venting fuel cap and connect the breather line to the filler pipe instead.  A quick way to test if the fuel tank breather is the cause of problems without having to diagnose anything, is to simply run the engine without fuel cap for a bit.

Main fuel line

I’ll describe most of the item in the main fuel line so you can identify where they are located in your vehicle:

Fuel Tank

Underneath your car.  Mostly at the back.  May have spare wheel and metal guard plates covering most of it.  May be somewhat inaccessible.  Just replace the hose to the fuel feed line and return pipe.  I’ll explain what the other lines are for later.

Fuel line

Looks something like this:

Note the old and new hose and different style clamps.  I just keep using the old spring steel clamps as no screwdriver is needed.

If the hose feels flexible still when bending between your hands, it is an indication it is not faulty.  If you sharply bend a hose a 180 degrees and diesel and bubbles in liquid appear, the fuel line is faulty.    Buy 1 or 2 meters of the stuff and replace where possible.

Water trap

The water trap is located somewhere in the engine bay or underneath the car bolted to the chassis near the driver seat.  I have yet to locate mine.  This is what it should look like.  There is probably some rubber fuel line connected to it as well.

This is an aftermarket generic model:

Don’t replace unless water trap indicator light on dashboard is lit.  As in my case it was located somewhere underneath the vehicle and the dashboard light was not lit, I did not inspect or drain it at this stage.

(Aluminium or) stainless steel fuel line running from back of vehicle to engine bay

Looks like this on my vehicle.  Rubber hose clamps are connected to these pipes with hose clamps.  If you see rubber fuel line hose clamps connected to metal tube, you have located the end of the metal fuel line.

Leave in place.  Unlikely to fail or cause problems.  Can contain globs of gunk, so if you have a compressor, flush with compressed air.

Inline primary fuel filter

This item may not always be present.  In my case it was part of the lift pump (see next paragraph).  When connecting metal parts using bolts and thread where you need to transport a liquid, often a “union bolt” or “banjo bolt” is used.  It looks something like this:

Fuel enters through a hole in the side and exits through the hole at the botton.  The bolt is hollow inside.  In this example there is a small ‘sock’ mesh placed inside the bolt that acts as a primary fuel filter to trap large particles.  You can unscrew this and clean it.  The banjo bolt is screwed in place with a soft copper metal washer ring in between.  This copper washer acts as a gasket and prevents air from being sucked in.  Ideally you need to replace any copper washers when unscrewing the banjo bolt.  If your vehicle is stranded beside the road you can reuse the existing copper washer if desperate.  If you want to do it properly, you can buy an assortment of copper washers, or use a blow torch to heat the copper ring until it glows hot red to anneal the metal.  This removes any dents and scratches from the material from previous use, making it suitable to be reused as a sealing gasket once again.  You can also use fine waterproof sandpaper and rub in a ‘figure 8’ pattern to remove indentations.

Lift pump (also called manual primer pump)

Here you see the lift pump that is bolted onto the injector pump.  Its only function is to get the fuel from the tank to the injector pump.  Inside are two small valves that open / close to make fuel flow only in one direction.  There is a small piston operated by the injector pump to keep it pumping fuel when the engine is running.  There is also a hand primer pump to prime the fuel line and to assist with bleeding air when flushing the fuel line.  You can use the starter motor for this purpose as well, but as you need to open and close a bleed valve at the same time it is recommended to use this manual hand pump instead.  More on that later.

In the picture you see the lift pump plunger mounted on top of the lift pump.  The black plastic part can be pressed down repeatedly to pump fuel.  It comes with a copper washer and is a direct replacement for the original plunger.  Simply unscrew the old one and screw in the new one.  Lift pump plungers are notorious for leaking and sucking in air when they fail.  Go to a parts store and replace your existing lift pump plunger.  This is the most likely part to fail in a diesel engine responsible for sucking in air.  Cost me about $30 AU or so for a replacement part.

Lift pump schematic:

Here is the original. Note the top bit needs to be screwed down when stored / driving and can be unscrewed if you need to manually pump fuel.

This is what a new lift pump plunger looks like:

Here you see the lift pump bolted to the injector pump with the lift pump plunger removed.  Inside the black round hole that is visible sits a small needle and spring.  Be careful not to lose this part as sometimes it can come out with the lift pump plunger when removing it.

Bleed screw (also called bleeder valve)

Here you see the bleeder screw just before the secondary fuel filter.  Also, you can see the lift pump plunger installed, as well as the new short piece of rubber fuel line.

The idea is to open the bleeder valve slightly whilst pumping fuel by hand to push out any air bubbles in the fuel line.  This is the most important roadside assistance operation you will need to master to get your vehicle going again, even if it is only for 100 meter at 10km/hour at a time.  More on this soon.

A bleeder valve looks like this:

The hose connector and size 10 spanner nut located at one end of the bleeder valve are left exposed in the engine bay clearly visible.  The other end is screwed into a hole.  By turning it 1/4 to 1/2 turn you can ‘close’ or’ open’ the bleeder valve whereby fuel (or air) in the fuel line can escape through the hollow bleeder valve.

[!] You only need to loosen it a quarter of a turn for fuel to enter through the hole in the side and out the top.  If you loosen it more than one or two full turns, outside air may be sucked in via the thread along the length of the bolt.

Secondary fuel filter

If you are going to the shop, please replace this item as well.  It stops microscopic particles from making their way into the high pressure injection pump.  As you can imagine, squirting fuel at high pressure requires small nozzles and a high pressure pump.  Any small particles could easily damage the internals of the injector pump.  Write down the model number of your current fuel filter.

Also get this:

If you haven’t got one, you can hammer a screwdriver through the filter and use that as a lever to unscrew the filter.  Always lubricate the ring of the new filter and the inside of the new filter with diesel fuel to prevent air leaks and for air to enter the injector pump.

Injector pump

You don’t want to break this.  Look after it.  It does not matter much now, but it helps to only put clean diesel fuel in your tank by filling up at proper fuel stations / bowsers.  Avoid driving with a near empty fuel tank as most contamination sinks to the bottom of the fuel tank.  The injector pump is not likely to fail.  If you bleed the fuel and the car engine idles smooth even for 10 seconds, it means the injector pump is working fine.  The injector pump is bolted onto the engine and is gear driven to determine the exact timing when to inject fuel into the cylinders.  You can remove the injector pump with the timing gear included, but for this you will most likely need to remove some other parts that may sit in your way.  You can then slot in a refurbished injector pump with its own identical timing gear.  You line up the engine gear and injector pump timing gear – there are marks stamped on each gear like 1 – 2 – 3 that need to be aligned.  Again, don’t worry about the injector pump at this stage.  It is most likely there is air being sucked into the fuel line.

6 cylinder engine injector pump with timing gear and bolted on hand priming pump / lift pump:

Injectors

Don’t bother about injectors just yet.  Yes, you may have a faulty injector, but it is more likely for problems to manifest themselves at the fuel line end.  You can just buy one injector, put it in place and if it doesn’t resolve the problem, place the removed injector in the next cylinder and repeat until you have found the culprit.  If that doesn’t help, you now have one spare injector you can use in case of an emergency.

 

Bleeding the fuel line.

This is it.  This is what you need to do.  This is what you need to do after having replaced the short piece of rubber fuel line connected to the lift pump and the lift pump plunger.  Even if you haven’t replaced these parts yet, this is what you need to do if you want to move your vehicle 100 meters at a time each time using a low speed of 10km/hour in 1st or 2nd gear:

Pour some diesel fuel in a small container and insert a 30 to 60cm long silicone tube.  The end of the tube needs to sit inside a puddle of diesel fuel.  This prevents air being sucked back in the hose later on.  I used a small raspberry jam jar with a thin metal screw-on lid.  Make sure to puncture the lid to let air out….  A longer hose works better than a short hose in my view.

Connect the other end of the silicone hose to the bleeder valve located just before the secondary fuel filter:

With a size 10 spanner, loosen the bleeder valve 1/4 turn.

Now press down on the black plastic lift pump plunger repeatedly.

You will see air bubbles inside the glass jar if the pump is working.

Initially you will see air and diesel fuel enter the silicone hose near the bleeder valve.

After a few moments you will see diesel fuel starting to fill the silicone hose near the bleeder valve.

You will need to pay attention to what comes out of the bleeder valve next.  If it is fuel + air, you will need to keep pumping.  If it is only fuel that comes out of the bleeder valve, use the size 10 spanner to close the bleeder valve.

There may be some air bubbles visible in the silicone hose away from the bleeder nipple that may be confusing; you can ignore air bubbles in the hose and simply focus on the 2cm of hose near the bleeding valve only.  Having your silicone hose and glass jar placed on top of the bleeder valve instead of dangling below the bleeder valve may help as this will cause the air bubbles and fuel to rise rather than fall, making it easier to interpret what is happening.

Tips

Do not open the bleeder valve more then 1/4 turn thinking this will allow more fuel/air to come out.  The hole inside the bleeder valve is very small.  The lift pump pushes only a small volume of fuel to match.  Even if you pump really fast, you can only get small amounts of fuel or air to come out of the bleeder valve.  This is about slow and steady rather than fast and furious.

The goal is to close the bleeder valve when the top of the silicone hose near the bleeder valve is filled with fuel and no more air bubbles come out of the bleeder valve when you press down the lift pump plunger.

Note: The fuel line from the tank to the lift pump is a good 3 meters.  If you are stranded beside the road because you ran out of fuel, you will need to bleed the entire length of fuel line.  If using only a small container you will need to repeat the process several times.  You can imagine 3 meters of fuel line holds more air/fuel than the small raspberry jam glass jar I used shown in a previous picture.  I simply emptied the full glass jar 3/4 into the car’s fuel tank using the fill opening.

Testing

Start your car normally.  If it doesn’t start after 15 turns, repeat the fuel bleeding process once more, just in case.  This is preferred over flattening the battery needlessly.  If the engine does start, do not rev the engine.  Keep it at low revs and use 1st or 2nd gear to move it somewhere safe.  You may even be able to get home.  If the vehicle is in a workshop or at home and you have started to replace some parts, you can rev the engine to see if it still sucks in air.  A full fuel line will allow you to drive 50-100 meters at 1500RPM in 1st (or if you are lucky 2nd) gear until new air bubbles will make their way to the lift pump / injector pump and stall the engine.

If you do get the engine to run, you can loosen each injector one by one slightly with the vehcile on the handbrake and the engine running at idle speed.  This will expell air bubbles or moisture at each injector.  The engine will run erratic while you perform this operation as one cylinder at a time will not be firing; this is acceptable and the engine should keep running.  This operation is a quick and easy and can be performed at any time the engine is running stable at idle speed with the gearbox in neutral.  Beware of spinning belts in the engine bay (!)

Finally, in the above picture you see there is a size 10 bolt in the top left corner of the injector pump.  This is a bleeder valve that can be used to drain air from the injector pump.  The injector pump bleeder valve is designed to not suck in air, so you can simply open this 1/4 turn to let fuel/air come out whilst repeatedly pressing down on the lift pump plunger.  Generally, this operation is not necessary as using the lift pump to prime the fuel line is sufficient to start the engine in most cases.

If you cannot get the engine to run at all, bleed using the manual primer pump and bleed valve.  Then loosen 1 injector before starting the engine.  This will lighten the load on the injector pump and may be sufficient to start the engine.  Alternatively  you can loosen additional injector connectors, turn over the starter motor a few times and tighten all injectors but one.  If you now turn over the starter motor for longer the engine might start and run.

If you really can’t start the engine at all, use a normal jerrycan of diesel fuel with a fuel hose connected to the lift pump.  Repeat some of the above steps to bleed the line and run the vehicle off the separate tank to bypass the main fuel line of the vehicle.

Shopping list

2 or 3 meter of rubber fuel line hose (bring original part)
Copper rings assortment (if available; re-use existing part if no other option.)
Lift pump plunger
60cm of silicone hose.  If you don’t know exact diameter, just buy a few at random.
Small (glass) jar with (punctured) lid.
Small 5L jerrycan with diesel fuel.
Clear safety glasses or a pair of sun glasses – don’t get diesel in your eyes working underneath the vehicle replacing fuel lines (!)

Optional

Secondary fuel filter (write down current fuel filter’s model number first)
Removal tool for large oil filter/ fuel filter.
Injector (1x)

 

Day 2

After having replaced the lift pump plunger and the rubber fuel line connected to the lift pump, after draining air from the fuel line the vehicle is still having problems.  It starts without problems and I can run the engine on idle or drive it at 1000-2000RPM under light load on level road without problems for a few minutes at best.  As soon as I put my foot down to quickly accelerate from idle to 2000RPM there is some stutter suggesting one or more cylinders is misfiring.  Note that 2000RPM under load is different from 2000RPM idling; driving a vehicle up a hill puts much more strain on an engine as revving an engine in neutral.  I can’t easily test the vehicle as our house is on a hill.  I risk not being able to make it back home.  I guess I could safely test the engine in the driveway by driving off in 3rd gear at 2000rpm (with a warm engine only).

There is no water in the oil.  Vehicle does not leak oil on the ground.  There is no blue or white smoke ever.  Car struggles up steep hills at 80km/h in 5th gear and falls back to 50km/h in 3th gear eventually, but lower gears are fine.  Radiator water tank loses water and needs topping up.  Radiator must have a leak somewhere, which does not help.  Friends have informed me that losing a cylinder i.e. blown head gasket results in white / blue smoke over time and poor idling combined with reduced power, but without stuttering.  Stuttering is more a sign of fuel starvation and does not indicate a blown head gasket..

So there is no need to purchase a compression tester or have a mechanic test compression (yet).

 

Diesel compression test kit


Use this tool kit to identify worn valves and piston rings of most diesel cars, trucks and tracktors.  The gauge has a range of 0-70 Bar/0-1000 Psi.  Comes with 9 different glow plugs and 4 injector adaptors:
*Glow plugs:
M10x1,0x83mm
M10x1,0x91mm
M10x1,0x102mm
M10x1,0x113mm
M10x1,0x119mm
M10x1,25x64mm
M10x1,25x135mm
M12x1,25x47mm
M22x1,5x118mm
*Injector adapters:
M20x1,5x75mm
M22x1,5x73mm
M24x1,5x88mm
M24x2,0x63mm

How it works
– Buy a diesel compression kit with glow plug adapters ($60 AU)
– Unscrew glow plug and insert a matching glowplug adapter from the diesel compression kit.
– Connect pressure gauge to adapter.
– Crank over engine using starter motor 5 times.
– Write down the cylinder pressure from the gauge.
– Press button on gauge stem to reset.
– Repeat for all cylinders.
– Write down values; any out of band low pressure values indicate a leak i.e. cylinder head gasket failure.

 

Head gasket failure types

Wrecking a vehicle

Call the local wreckers, get $500 – $750 for parts (depending if they need to pick it up), take the license plates off the vehicle (important) and take proof of wrecking and 2x plates to a Department of Transportation office and complete a form to properly deregister the vehicle.  Sometimes vehicles are left stranded beside the road without license plates.  I could drive it off a cliff, if only I could make it to the top of the cliff first.

 

Next steps

If I assume for now compression is fine, there is not much I haven’t already checked.  My action plan for tomorrow:

  • Empty out the vehicle in your driveway while it is there and not stranded beside the road!
  • Take some diesel fuel with you if you need to bleed fuel lines unexpectedly.
  • [!] Clear vehicle ground by following the negative lead and clean the chassis.
  • [!] CHECK BLEEDER NIPPLE FOR AIR AGAIN.
  • [!] Connect small container with fuel directly to lift pump to bypass fuel line, water trap, fuel tank, hoses, etc.
  • Decant fuel from bottom of tank and let it settle to check for pollutants.  Use mobile phone boroscope to look inside tank.
  • Check fuel tank intake to see if it is gummed up or clogged or something perhaps.  May have to remove / flush fuel tank somehow.
  • Drive car under load without fuel cap to see if tank breather is blocked + inspect.
  • See if you can use bleeder valve after lift pump and bleeder valve on injector pump with engine running?
  • Bleed lines again using same glass jar placed above lift pump to see if that is easier.
  • Bleed lines again using a larger container for longer.
  • Check for air bubbles in radiator to see if head gasket is blown.  Having a leaking radiator does not help.
  • Locate the water separator and empty bowl in a container to inspect contents.  Replace O-ring washers if necessary.  Perhaps you can bypass water separator temporarily to rule out it doesn’t suck in air?
  • Check water separator rubber fuel lines.
  • Is an injector borderline faulty perhaps?  You could buy one and use it to test injectors one by one.

 

From the Internet

“Other things I would check is the fuel pick up in the tank.It has a piece of fine gauze over it.Over the years they get clogged up with all the gunk that comes in with your fuel and obstruct the fuel supply.”

“Dirty fuel injectors may cause the engine to run lean which will in turn, cause hesitation when accelerating.

“A vehicle that hesitates while accelerating or while driving up a hill may have a weak fuel pump”

“Might be worth checking if you have gotten some dirty diesel with maybe water in it. Filling your tank will not help; you have to empty and refill your tank and see if that helps.  Check to see if you have crud in the tank too..”

“Fuel filter seal”

“Bad cracked or clogged pickup inside the fuel tank”

“When I crack the bleeder nipple it is full of air again.  I have replaced all the flexible hoses up to the tank and all the filters, I can’t see any evidence of a fuel leak anywhere up to the tank.  Once I have it started I normally set the hand throttle to about 1000rpm and let it sit. Today I had it at 2000rpm and still only managed 17 minutes before it died again.”

“I actually ran into this issue myself and I had a crack in the metal fuel tube that comes off the tank to the main fuel line. (It’s the line he is pointing to with the blue pencil, it connects on top of the tank). I dropped my tank to find it and fixed with a small amount of jbweld around the base of the tube”

“Loosen the fuel cap and see if it runs better. Maybe the vent is clogged. Also, with the cap off, look into the tank while running and see if you’re getting a return flow. The flow should increase with rpm. No flow means weak pump and it’s not getting enough fuel. The injector pump will produce more fuel than needed by the injectors. The lift pump has to keep up.”

“You can bypass the lift pump too and just gravity feed into the injection pump from a temp fuel container.  You can use anything, a soft drink bottle or a glass jar work well since you only need to run for a few minutes to diagnose. Get some rubber fuel line and a cheap $4 inline filter just to be on the safe side.”

“If you don’t drain your water separator regularly the bottom rusts out”

“I was told it was a earth problem.  Cleaned the earths up and put another earth lead on and never had another problem”

“The water trap is attached to the chassis under the driver’s seat.”

 

Day 3

Found the water trap attached to the chassis under the driver’s seat with 2 pieces of hose that I have since replaced:

There are no o-rings on the top and bottom bolts to let air in the top and drain the bowl at the bottom.  Shop didn’t have any that small either, so just put it back the way it was.

There was no water in the bowl, but there was a fair bit of dirt:

Cleaned battery ground on chassis located 10cm from battery negative terminal.
Negative terminal cable keeps going down and appears to be connected to outside of sump.
May need cleaning as well (skipped for now).

Bleed fuel.
After 20-30 strokes I finally have a bit of fuel in the silicone hose.
There are no more air bubbles, but also the pump does no longer appear to be pumping (no bubbles in liquid inside glass jar).
It feels like there is a blockage of sorts.

Remove fuel cap.
Blow air into hose connected to lift pump in the direction of the fuel tank.
It took me a lot of effort which suggests the line to the tank is airtight to some degree at least.
You should be able to blow air through at a slow speed with lots of effort.
Next, use lift pump plunger with glass jar container to start bleeding lines again.
This may take a long time now that lines are full of air.
Only now put fuel cap back.

If bleeding was successful this time, you may have a problem with the fuel return line.
If bleeding is still problematic, the mesh filter pickup in the tank may be clogged.

Bleeding was still problematic.  At some point the plunger does not seem to pump any more fuel/air out of the bleeder valve.  No air bubbles in liquid in glass jar container.  If I close the bleeder valve, wait 10 seconds and start again it works for a bit, but it is not great.  (You need to put an air hole in the lid, stupid!)

I then started looking at the tank to determine if:

  • the breather was clogged (tank unable do expell surplus air).
  • the fuel return line was clogged.
  • the pickup in the tank was clogged.

Inspection opening

There is an inspection opening under the carpet:

Remove sender clip

Note this vehcile only uses a lift pump and injection pump.  There is no fuel pump inside the fuel tank.  Only a fuel sender unit.  The fuel sender unit is nothing more than a fuel float that controls the fuel level gauge and the ’empty fuel tank’ warning indicator light on the dashboard.  It is similar to a float in a carburator or toilet cistern.

This is pretty useless, but at least we can see inside the tank for the first time.  Looks pretty clean:

I found this on the internet where someone had cut this type of fuel tank in half to make it fit a different vehicle:

My fuel tank is in a lot better condition.  Can’t see the pickup element unfortunately.

Breather

A fuel tank needs to breathe.  Most new cars have a breathable fuel tank cap.  Mine does not; the fuel tank has a separate breather line.  If the breather is clogged, the fuel return line may not be able to push excess fuel back into the fuel tank.

The easiest way to test is to (bleed fuel line and) drive the vehicle with the fuel cap removed for a bit.  In my case the stutter / judder under load symptoms were present after driving 1.5km with a thoroughly bled fuel line still.  So from here it is pretty pointless, but a useful excercise still.

It works something like this:

If we follow these hoses on the fuel tank we end up near the filler cap.  Looking into the rear wheel well, just below and forward of the fuel door one can see a number of hoses behind the rock shield [77286] metal plate.

If we look inside the vehicle we find “the octopus” !

The four connectors at the bottom connect to the evaporation hoses on the fuel tank.  The connector at the top goes back the same way and connects to a metal line underneath the vehicle and eventually loops back in a gentle bend inside a crossbeam of the chassis where it breathes out excess fumes.  Mine had a small white plastic fuel filter placed in the line to act as a separation valve to prevent fine dust from entering the fuel tank (just visible in top left):

When I blow air through this filter from the top down to the bottom, with a bit of effort there is a steady flow of air, indicating the breather line is not clogged.  Also, as I had been driving without fuel cap already and that did not solve the problem, this confirms I am looking in the wrong spot.

The overfill hose simply connects back to the filler pipe.  You can just see the metal bend in the picture.

Fuel return line

This is where the fuel return line connects to the injectors (see orange circle):

From here it goes back to the fuel tank:

A fuel feed and return unit looks like this.  Note these are pictures taken from the internet:

Here is one shown with a sender unit:

One of the pipes supposedly has a mesh filter sock connected to it.  This would be the fuel feed line and the other pipe would be the fuel return line.  I can’t really tell which is which from the above pictures.

Fuel lines can be clogged by globs of gunk and are sometimes flushed from front to back with compressed air.  Fuel tanks may need to have rust removed using acid or by inserting a small chain and shaking rust loose.  Fuel tanks can be recoated internally.

 

DAY 3 final thoughts

I could blow air all the way into fuel tank from lift pump, so fuel pickup is clean.
So far all hoses have been in good condition; there is no reason to replace fuel feed + return line.
Fuel return line is not likely to get clogged.
Car stutters when under load.
Lift pump does not seem to lift enough fuel.  Could be worn.
There could be a bad injector as well.
Car runs fine at idle speed in neutral for 10 minutes, or at 2000RPM in neutral for 2 minutes, suggesting fuel line / lift pump is not the problem.
Checked airfilter as well

I need to more clearly describe the “stuttering / juddering under load” symptoms:
– If I bleed the fuel line 10 times using a 100ml container, I can drive a cold engine uphill/downhill for 1 kilometer before the problem starts manifesting itself.
– I don’t know if it is related to air in fuel line, low fuel pressure (lift pump), injector pump, injectors or a blown head gasket.
– Head gasket will affect idling so that is not likely.  What if head gasket only leaks when under load and engine is warm?  Is this possible / likely?  Vehicle does not leak oil, there is no smoke, not even when engine is hot and stuttering / juddering, suggesting fuel starvation instead.

Option 1
Gravity feed a small container of fuel directly into lift pump bypassing main fuel line + ziptie + drive.
When pumping to bleed air, see how much fuel each stroke pumps and if at any point it stops pumping as it has done before (suspicious).  This saves you having to do step 2a + 2b + (6):

Option 2a
Drop tank and inspect fuel feed & return inside tank + fuel pickup filter sock.

Option 2b
Replace fuel tank feed & return line.  I haven’t done that yet as I couldn’t reach it before.

Option 3
Get lift pump, injector pump and injectors off Ann’s old engine at Spena’s garage in Mareeba.

Option 4
Rebuild lift pump.  Note the different valves it uses.  If one leaks, it means not enough fuel under load.  Needs copper ring assortment.  Turns out my bleeding jar just needed a hole in the lid….stupid me…

Option 5
Ring P & H mechanics and ask for Roy.  P & H mechanics is permanently closed.

Option 6
Measure fuel pressure / cylinder pressure.

Option 7
Ring wreckers.

 

I think I will start with option #3 tomorrow, as it is good to have parts before Ann’s old engine is taken to the dump.  Then, just swap out the lift pump, test bleeding performance and optionally gravity feed the lift pump and if desperate replace injectors.  Buy some copper ring assortment from Supercheap Auto or Repco, or order from the internet for future use.  That should keep me busy for a day.

 

DAY 4

Mechanics still have Ann’s old engine and will hold on to it for a few more days.  Won’t allow anyone in the workshop (insurance).  “Can’t you come and pickup the engine?”  “Yes, if my car would drive (chicken – egg)…”.

Observation #1: When you use a glass jam jar as an air bleeding container, make sure to puncture the lid to create an air vent hole.  Without an air vent hole, you have a perfectly sealed container you can’t push fuel or air into the container without letting air out!

Even if you do everything right, it is easy to get wrong still.  When the hose fills with fuel any air bubbles will become trapped and move far less.  The jam jar will no longer have air bubbling out of the submerged end of silicone hose as it now starts to receive fuel.  It becomes difficult to see the flowrate the hand pump is producing.  You have to hold the hose vertically and higher than the bleeder valve.  You can now look for a column of rising fuel instead of a horizontal flow of air and fuel.  It may be a good idea to close the bleeder valve for now and start bleeding again using a 1/4 filled glass jar with an empty silicone hose from scratch.

Observation #2: I can run the vehicle on a small drinks bottle with diesel fuel without problems for a short while.  Results were inconclusive.  I need to try with a larger bottle as the car is very thirsty…I emptied the bottle and got stranded beside the road…again.

Observation #3: All fuel feed hoses have been replaced.  Spring steel clips may not be airtight.  Return hose is different diameter and located inaccessible behind air intake manifold.

 

Success!

Went to parts store to buy a fuel container that would better fit the fuel hose so I could test drive the vehicle using a larger separate fuel container this time.  Turns out the parts store also does repairs.  As the wreckers is next door this can go one of two ways.  Turns out the car drove 100% fine without problems on a separate fuel container.  You can just use a normal fuel jerrycan on the passenger seat with a 3 meter long fuel line.

The mechanic will drain and lower the near empty fuel tank, inspect the fuel (feed) line, the feed line pickup and filter.

Cause of problems:

Microbacterial growth in the fuel tank.  Lots of small black specks floating in the fuel.   When the fuel tank was drained, a big blob had collected in the fuel tank sump.  It must have partially blocked a fuel intake line causing problems under load but not so much when idling.  Fueled up at the bowser and put in a bottle of Fuel Doctor (microbial growth dispersement).  Car drives like new again (sort of).