Isuzu Trooper Owners Club UK™

[Jasetheace]

Hi Everyone I hope you can help.
My 3.0 litre Trooper, year 2000,  has developed a misfire but its horrendous. A few weeks ago I had to Change the fuel tank as it rotted out. This was all fine however it had had trouble starting and I found the Glow fuse blown. Replaced that and the 4 glow plugs and for two weeks it started and ran fabulous.

Then the other day it started fine and as I drove down the road it lost power, lots of white smoke then it picked back up and was fine all day.
That has been getting progressively worse to the point where I have just driven home from work, 2 miles, and it has taken me 10 minutes!!!!

It started and I went 100 yards and it started to miss, bit of smoke. then it misses even more down to what feels like two cylinders. I sit with foot on floor, it chugs and shudders for a minute or so, clouds of grey smoke, then picks back up, smoke clears and off I go. Few hundred yards and it does the same. Pull over, same then another couple of hundred yards and so on. Its now completely undriveable.

Ive had it about three years now and its been a really good truck but its now P**sing me off. There is no management light up and nothing comes up on OBD. The previous owner told me that it had had the recall injectors, new turbo and clutch and flywheel and Ive done about 7k miles in it.

Any ideas before I burn it.
Many thanks Jase

[Google]

[Gribble]

Hi , that sounds like fuel to me , has it had a fuel filter change after the tank was done ? Try a clear filter in the line to the mechanical lift pump from the fuel filter and see if airs getting in and work back from there .
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2 New Troopers !

[Jasetheace]

Hi, thanks for reply, that's what I thought, but ive not touched that end!!! Ill try and change filter and see what happens.
The trouble is my little primer pump has never worked. I was wondering whether this needs changing as I know they can suck in air? Just odd how it just happened though?? it now won't start at all this morning.

Jase

[Gribble]

Latex glove time then  
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2 New Troopers !

[Jasetheace]

So I got  a chance to look at it today, I thought for test purposes I would miss out the fuel filter and join the two fuel pipes together.
Now I don't understand my result so Im hoping some light can be shed????

I can draw fuel from the tank with a squeezey bulb hand pump, all good connect it to the feed pipe, wont start, take pipe apart, no fuel?? Put feed pipe straight into a gallon can of diesel and it will start once fuel has got to injectors and runs fine. Take pipe out of can and connect to pipe from tank and once fuel is gone from pipe it stops.

Fuel comes up from the tank by hand easily but for some reason it wont stay up when connected to the engine.

Any ideas??

[Browndoff]

It all sounds like there's air getting into the fuel-line. The fuel-pump just puts a little negative pressure in the line from the Primer / Filter and air-pressure in the tank pushes the fuel along. AS the old tank was replaced 'cos it was rusty - it's highly likely that the STEEL fuel-lines are rusty too - that'd make 'em leak and let in AIR! Rubber connectors become 'perished', too and that makes THEM leak!

The rubber-bulb hand-pump probably creates a bigger pressure-difference than the engine's own fuel-pump can manage - so it can't overcome the leaks as well as the hand-pump!

If your old Primer / Filter cannot be re-furbished, get one from a scrap-yard, clean it thoroughly and it should last you forever! Don't try to run it without a filter - they're REALLY necessary!
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2002 LWB Trooper 3.0L
I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.

[Jasetheace]

Thanks for reply, Ive only by passed the filter for test purposes. Ive checked the metal pipe all along but I cant see any leaks or any of that black rust you get when fuel is slightly seeping through.
I think I will substitute the metal pipe for rubber all the way and see if that does the trick.

If that fails then eebuygum spares or repairs here we come!!!!

[eithan h]

so where does the air pressure in the tank come from?

[Browndoff]

"I think I will substitute the metal pipe for rubber all the way"            I'm inclined to suspect you meant 'rubber for metal' - but I think the best option would be to buy some ¼'' copper tube [from plumber-suppliers] and replace with THAT. It won't rust, it's easily formed to any appropriate shape [without collapse of the tube] and it won't need as much SUPPORT as would a rubber fuel-line.

"where does the air pressure in the tank come from?"         Almost ALL pumps operate on the basis of atmospheric pressure forcing the fluid to fill a 'gap' created by the pump forcing the fluid towards the 'end-of-the-line'. In this case the pump forces fuel into the galleries in the Head, reducing the pressure [below atmospheric pressure] in the fuel-line from the Filter and so atmospheric pressure in the Tank pushes the fuel along the line. If there is a rust-hole in the line, then air can come in THERE and NOT draw fuel from the Tank.

Even the massively high-pressure pump for the hydraulic firing of the Injectors is 'refilled' continuously by atmospheric pressure pushing the filtered oil into the low-pressure side of the HPOP.
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2002 LWB Trooper 3.0L
I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.

[eithan h]

problem is that theory only works as long as there is a gap in the fuel line for the LIFT PUMP to generate a vacuum, as soon as fuel fills that vacuum then  there is no vacuum for the fuel to be pushed in to at atmospheric pressure. hence most diesels have a LIFT PUMP to lift the fuel from the tank they do not rely on atmospheric pressure to push the fuel along the line.
the hpop is also feed at up to 40psi from a low pressure pump which is nigh on 3 times atmospheric pressure from behind the flywheel it is not pushed in by atmospheric pressure as it would not be able to keep up the flow.

[Jasetheace]

So, Im now thinking the air in the system theory was a red herring!!! This evening I substituded the fuel pipe with a rubber fuel pipe from tank to fuel line in.
It still wouldn't start so I disconnected it and put the "In" pipe in can of diesel, it still would not run.
There is the odd cough as one injector fires but nothing more.

Ive cut the white wire, nothing!!

Ive put 2 lires + of oil in, still nothing!!

Any Ideas??? Could the fuel pump have gone?

[eithan h]

could be cam or crank sensor or rpcv stuck or ecu, might be time to get it on a tech2

[Jasetheace]

should they show up on OBD?

[Gribble]

In the old days ,long before young eithans time   us ole  southern plant fitters would suck the diesel up from the tank to see what happened !

Northern fitters would blow down the line as they cant take the taste of diesel too well , same thing really if you cant blow to the tank the lines blocked

If you got no diesel you went looking for trouble lower down the line as most lift pumps are lazy .

In your case the engine needs to wind over a bit to get the fuel gallery up to pressure so the injectors purge the air and inject .

Getting fuel to the injectors is old skool stuff ,you need a flow back from the return line out the back of the head ,its the rubber pipe with the white thumb clip on so when thats going on from the hand primer the look to the other things as Master E has posted .
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2 New Troopers !

[Jasetheace]

I haven't yet looked at the return pipe from the head, but I know what your talking about. I rebuilt the head and replaced the injector sleeves so I have an understanding of the way the fuel goes through and fills up the pots and the excess flows out the back and back to the tank.

Now, my question,  if I hand pump the fuel the hand pump should never go hard as there is a constant flow, is this correct?

Because if I hand prime the system it goes rock hard and I cant pump it no more, is this right? does it sound like the return might be blocked? Is this common?

I suppose only pulling the pipe off and pumping/crancking will tell, but I thought id ask.