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GQ TD42 Chasing Fuel Issues

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8K views 22 replies 7 participants last post by  Peter Mc  
#1 ·
Hi all, this fuel issue is driving me crazy. The old faithful is struggling to run thanks to air in the fuel lines.

When i go to start the rig, it starts first go no worries. But then after about 1 or 2 minutes of running the revs begin to die and it starts wanting to stall. If i bring the revs up manually it will keep running but it wont idle. if it manages to stall it wont start again until i prime it, and then the engine fires and runs alright. Sometimes i need to prime for ages other times only little bits. Other times if i just keep the revs around 1200 or higher for a while the air comes out of the system. It splutters a bit but it eventually bleeds all the air out.

I have just had the injector pump replaced proffessionally, new injectors, new injector lines, new spill rail, new washers in all parts of the fuel system, i have installed all new soft fuel lines, new hand primer pump, new fuel filter.. there are no visible fue leaks anywhere when turned off.

I tried the clear fuel line trick, deffinatley air coming up. From where i have no ****ing clue. Any ideae?

Cheers

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#2 ·
The first thing I would do is get a bucket/container of fuel run the hose directly to the pump, Ensure it runs etc.. Turn it off and leave it for however long you need for the problem to surface.
Restart and check again. If there is no problem. Then look at the delivery to the pump.

Bypass the primer (as its the most likely cause even though its new) first.
Then from there start going backwards until you find where its leaking.
Its rare you will actually get a diesel leak from a bad connection as its under vacuum the entire time (in a normal setup)
You can try to use compressed air into the tank and see if fuel seeps out anywhere also.
 
#5 ·
Diesel tuner - thanks ill try that air trick.

Gqshayne - checked those too seems to be fine but i havent dropped the tank to make triple sure

Hz_350 - nah same water trap on bottom of filter but with a new seal.

Also, new development. It seems to me that the air leaks are more common if i am parked on any form of incline or decline. Flat ground seems to produce almost perfect starts even after 2 days, but any sort of angle for even a couple of hours is enough to make it splutter. Could also just be coincidence but im not sure to be honest. This is driving me insane.. [emoji35]



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#6 ·
Ill put money on it being the water trap mine leaks aswell showed up after fitting a lift pump very common to leak. May be leakinh from the little drain screw. If it leaks the fuel is possibly draining back to the tank on a hill

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#8 ·
So today i gave up. I took the old girl to a diesel specialist. For interest sake when i find out what the problem was, ill post it up. Might help someone in the future 🤙

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#11 ·
it would help you find your leak if it was back at the tank.
but it does help longevity of fuel pump. makes little difference performance wise na but turbo pumps it helps.
putting one on removed a massive flat spot on my old pump. flat spot was so bad it would put you thru the windscreen.
 
#12 ·
Hm very odd. I had one in before the turbo pump got put on. Multiple diesel specialists advised me to take it off as it can play with timing internally apparently.. ill see how it goes without it. Sounds like they might have fixed it anyway, but im waiting for another couple of test days to see if it keeps draining back or not

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#14 ·
Hmm, i beleive they already advanced it to td42t spec anyway while its NA as to allow for the turbo later. So they would be worries about even further pump advancing on top of that again

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#15 ·
When i go to start the rig, it starts first go no worries. But then after about 1 or 2 minutes of running the revs begin to die and it starts wanting to stall. If i bring the revs up manually it will keep running but it wont idle. if it manages to stall it wont start again until i prime it, and then the engine fires and runs alright. Sometimes i need to prime for ages other times only little bits. Other times if i just keep the revs around 1200 or higher for a while the air comes out of the system. It splutters a bit but it eventually bleeds all the air out.
Mine was doing exactly this. It was driving me nuts. I put new fuel filter in and pulled off that banjo bolt where the gauze filter is supposed to be on the IP (turns out no filter in mine), then I bled the whole system.

I had a small leak in the advance plate 'o'-ring seal also, so I replaced it since I wasn't sure if that could result in an air leak. Cost me 20cents from a bearings and seals joint. Wasn't the proper Nissan seal with flat top and bottom, but it was close enough.

Whatever the case, the car runs perfectly now. Better than it ever has.
 
#20 ·
Okay so update!

The mechanics found two tiny tiny splits in the end of two return lines from the spill rail to the IP, and from the IP to the return hardlines. These were overlooked apparently. So they have been replaced. The o rings inside the water trap have been replaced, i didnt know you could replace those o rings. This seems to have solved some the air issue, but not completley.

I was told to take it for a good drive to get all the air out. So i did. Probably drove 5km to destination, drove arouns about 2 or 3km and then turned her off. After about an hour of walking the dogs we got back and i tried to start the car.

Now she didnt want too start, she took a fair few turns to go. This included a good 10 second glow. After she did run, i drove 300m and stopped, when i pushed the clutch in the strangest thing happened. I push the clutch in, the engine doesnt die completley, but the revs drop below idle, and then at about 150/200revs slowly come back up to idle. So it doesnt completley die but it doesnt stay at idle either. Not to mention its still not starting straight away either so there must be an air issue still somewhere.

After seeing that rev thing happen, we took off up the road, but once in second gear under load, she started to stutter while increasing revs (practically misfiring). I would beleive this would be an air issue still. This is driving me insane.. ive had these stuttering issues before and was one of the reasons i rebuilt the IP along with turbo comparability..

Any other idead ladies and gents?

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#21 ·
Looks like the tank is going to be replaced. Must be an issue inside the fuel tank. Possinly broken baffling or something of the sort. New tank, sender and pickup will go in within the next couple weeks and ill go from there. :)

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#22 ·
Alright, so i found the issue and its fixed!

The 3/8" hard feed line to the engine was rubbing on the body above the drivers side coil brace. Such a hard place to find an issue. I found it by using a cloth and a high pressure air fitting on a compressor and pressurising the tank to get fuel to the engine. It pissed out fuel as soon as i pressurised the tank.

Along with that, the old sender unit in the old tank had a dodgy pickup and the pickup line was welded together to be extended and was the most eneven dodgy welding ive seen. Terrible.

So new brown davis 148ltr tank is in, this tank requires no modification to the sender unit. So i put in a brand new genuine pickup/sender unit and green pickup plug. New o-ring to seal it up too. Now my fuel gauge works!

I have also run new soft fuel line front to back, and insulated it in thin hydraulic line as an outet protective layer. This is run following the exsisting hard lines.

This all combined has made the world of a difference, the new IP and new injectors plus a solid delivery of fuel has made it drive beautifully. Now since the tank fiasco, i have replaced every single component in the fuel system including lines...

Only took me 3 months and 3 mechanics to find it..

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