Nissan GQ Patrol - Petrol problem

[Luddite]

I thought I should pass on my experiences solving a similar prob on my dual fuel TB4.2E GQ. The story began when I ran on gas for ages, keeping almost no fuel in the LRA petrol tank. Then came the day I ran out of gas, switched to petrol as I drove and had the 4.2 trying to conk out on me as I put my foot down. With much backfiring and lurching, I got to a servo, put in more petrol but the prob remained the same. Gas ran no worries, but petrol switchover at idle led to the 4.2 trying to conk out, with very careful nursing of the go pedal keeping it going. On the freeway, a switch from gas to petrol was possible, but the 4.2 felt underpowered, and any sort of accelerating led to a 4.2 liter hissy fit. The problem turned out to be the fuel pump. I didn't realize that the in tank type of pumps rely on the fuel in the tank to keep them cool. When I dropped the tank, the pump/sender assembly came out easily and I saw the rubber base the pump sits on was melted looking. The LPG conversion had led to the LRA petrol tank being used, and the in tank pump was replaced at that time. The dodgy el cheapo crimping connectors that connected the pump leads to the original in tank pump wiring were, in a word, shitful. It never ceases to amaze me how blokes spend big bucks on after market stuff, but the wiring seems to be consistently crap. So - I got a new Goss pump (GE132), and soldered new wires from the lugs on the underside of the fuel tank sender cover, new terminals soldered on the ends of the wires where they bolt onto the pump, put it all together again, put fresh fuel in the tank, started on petrol first time and it runs sweet. Low fuel had cooked the old pump. Even though it was running, the delivery was marginal and heavy acceleration took more than it could provide, which is why there was much crappy running on petrol. I suspected the fuel pressure regulator initially, which is the little can at the front of the injector rail - but a swap showed that it was not that. The pump wiring was so poor, there was no way I could not fix that up as it was a breakdown waiting to happen. Lessons are: 1) don't let petrol level get too low - the pump will cook and 2) do good wiring or don't do it at all.

[RubberDuckieGQ]

Hi Luddite, I have a 4.2L GQ as well and having a similar problem. Only difference with mine is that it's really inconsistent i.e. some days runs fine on petrol, other days it won't idle on petrol at all and just conks out and have to switch to gas.

We bought our truck a few months ago and it doesn't look like the previous owner ran it on petrol much at all, also think it's been tuned to run entirely on gas rather than getting a balance. Looking to get this fixed up next week, fingers crossed it won't be too pricey!

[Bogdat]

I had the same problem,ran great on the gas but struggled when switched onto the fuel. I had the fuel injectors cleaned and changed the fuel filter. Changed the leads and dizzy but still no luck. I was told it couldn't be the fuel pump as it pumps fuel. The other thing against pulling the fuel pump out was the after market tank doesn't sit above the opening in the body of the vehicle. this required removal of the tank 80l very tight fit. After money and lots of thought, decided to take the tank out. Found the problem, a dirty sock on the pump intake. it cost very little compared to everything else.



Turned out it was the sock on the fuel pump.

[Bloodyaussie]

Hey new guys can you head over to the intro section and say G'day and tell us a bit about yourselves ... just polite and all!!!

[anasaz09]

That is exactly the same problem I currently have, if the rpm is under 2000 it cranks and stuff, if above, it works like a charm

one question, what is the difference between gas and petrol? it may sound like a stupid question but Im new here and would like some help

[Sandman82]

Hi all, did anyone find a true fix for this issue. I have a similar problen on a carby 4.2, dual fuel. The car ran fine on both fuels and regularly was swapoed between each. A collapsed muffler was causing it to struggle which i eventually replaced after multiple patch ups. Had trouble with idle on petrol after that however plenty of power. On gas it ran fine. Also lagged on take off petrol only.
I rebuilt the carby so the power piston stopped lagging.
Ran perfect on fuel, swapped to gas also perfect. Swapped back in and it wont idle.
Tested the gas valve by shutting off the tank so its not duel fuelling. Fuel pump is fine and new filter.
Any ideas?

[Arfa Brayne]

Same problem with my TB42E.
Runs fine on gas, but switch to petrol and it will idle OK but coughs and farts when you push the go pedal.
It was suggested that the fuel strainer was clogged, so I dropped the belly tank and pulled the pump out. - sure enough the pump strainer was pretty dirty.
Dirt and dust had entered the tank from a split breather hose. The 3/4" breather that runs to the filler cap had turned hard and split right near the tank. Some clown had used heater hose instead of fuel vapor hose.
Because the tank was a bit of a b!tch to remove, I figured it would be smart to test the pump before refitting the whole shebang.
I made up a test jig from some spare hydraulic parts, variable pressure relief valve and an air compressor gauge.
The fuel pump was only pushing about 1.5 litres a minute at 17psi . Above 20psi the flow stopped.
Specs are hard to get, but it should push about 4 litres/min at 40psi.

Ordered in a Fuelmiser pump FPE284 which cross referenced to the EP128AU Ac-delco pump. Base is different, terminals are different, won't mount on original Patrol tank sender. Modified the sender with some 8mm rod, fuel rubber and hose clamp to take the FPE284 pump, drilled out the terminals to fit.

Tested the new pump on my test rig - 4.5 litres/min @ 40psi, 3 litres/min at 60psi, pumped up to 80psi before the pump pressure relief valve let go.

Need to fit it all back together tomorrow.

[dom14]

Same problem with my TB42E.
Runs fine on gas, but switch to petrol and it will idle OK but coughs and farts when you push the go pedal.
It was suggested that the fuel strainer was clogged, so I dropped the belly tank and pulled the pump out. - sure enough the pump strainer was pretty dirty.
Dirt and dust had entered the tank from a split breather hose. The 3/4" breather that runs to the filler cap had turned hard and split right near the tank. Some clown had used heater hose instead of fuel vapor hose.
Because the tank was a bit of a b!tch to remove, I figured it would be smart to test the pump before refitting the whole shebang.
I made up a test jig from some spare hydraulic parts, variable pressure relief valve and an air compressor gauge.
The fuel pump was only pushing about 1.5 litres a minute at 17psi . Above 20psi the flow stopped.
Specs are hard to get, but it should push about 4 litres/min at 40psi.

Ordered in a Fuelmiser pump FPE284 which cross referenced to the EP128AU Ac-delco pump. Base is different, terminals are different, won't mount on original Patrol tank sender. Modified the sender with some 8mm rod, fuel rubber and hose clamp to take the FPE284 pump, drilled out the terminals to fit.

Tested the new pump on my test rig - 4.5 litres/min @ 40psi, 3 litres/min at 60psi, pumped up to 80psi before the pump pressure relief valve let go.

Need to fit it all back together tomorrow.

Let us know how you go with this.

[Arfa Brayne]

Put it all back together and runs fine.
Problem solved.
Except the "O" ring seal on the sender unit is leaking fuel - I thought it must have been the split hose that had caused the stains, but fuel is definitely leaking from the top of the tank.
Bugger !
Means pulling the tank out again - after I use all the petrol.

[dom14]

Put it all back together and runs fine.
Problem solved.
Except the "O" ring seal on the sender unit is leaking fuel - I thought it must have been the split hose that had caused the stains, but fuel is definitely leaking from the top of the tank.
Bugger !
Means pulling the tank out again - after I use all the petrol.

Hmmmm...not sure how that happened!!!

I just went through your original description of fuel pump mod you did.

Fuelmiser pump FPE284 is totally different from the original intank one.
I'm not sure why you had to use Fuelmiser pump FPE284, instead of replacing it with an original one.

I can't understand why it should leak fuel, unless the O ring seal of the sender unit assembly was damaged badly enough.
It's not that easy to damage it.

Another thing you need to consider is that the fuel pressure of the Fuelmiser pump FPE284. It may be too high.