Nissan GQ Patrol - Petrol problem

Hi guys, just thought id ask if anyone had any ideas why my Patrol runs on gas, but struggles to run on petrol. It starts fine on petrol, but then conks out. It also runs on petrol if i keep the car on high revs - 3,500+ - but again conks out when i take my foot off the accelerator. I have tried changing the leads, plugs, adding a fuel injector cleaner and re-adjusting the timing, but none of those things seem to help. Does anyone think it could be the fuel pump? How could i test it and where exactly on my car is it located?

Any help in this matter would be greatly appreciated.

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Originally Posted by Danchez

Hi guys, just thought id ask if anyone had any ideas why my Patrol runs on gas, but struggles to run on petrol. It starts fine on petrol, but then conks out. It also runs on petrol if i keep the car on high revs - 3,500+ - but again conks out when i take my foot off the accelerator. I have tried changing the leads, plugs, adding a fuel injector cleaner and re-adjusting the timing, but none of those things seem to help. Does anyone think it could be the fuel pump? How could i test it and where exactly on my car is it located?

Any help in this matter would be greatly appreciated.

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Hey mate - don't think it would be fuel pump as it normally just dies. To test that, remove the fuel line on the bottom side of the filter whilst the car is stopped (beside the battery) and put a small bottle over the end of the fuel line to catch petrol - get someone else to turn over the ignition briefly and then off again ( literally a second or two) and fuel should flow into the bottle, if not the pump could be stuffed. You could also try removing (again whilst stopped) the green coloured transmission relay and plug it into where the green fuel pump relay is and repeat above (relays are beside/at the rear of the battery also) - this will test to see if it's the relay. If you get fuel, the relay is stuffed, if not, back to the fuel pump. The fuel pump cover is located under the carpet in the far back - you have to remove the scuff strip and roll the carpet back - but unless you know what you're doing, not much you can do there other than check the wires going to it.

That all said, again I think the pump would be fine (as such) if the car is constantly starting and then stopping under idle. Could be similar problem to what I had with mine - coolant temperature sensor is knackered as it sounds similar to the problem I had (dual fuel also, ran fine on gas, but a dog on petrol - didn't quite stall, but was close to it though). Guys on here who'll be able to narrow it down, but if it is that, it's an easy fix (and reasonably cheap - $42 I paid for the sensor). Fingers crossed!

Someone will be along with more to assist mate (Tony!!!) and he'll probably get up me for responding at all and mis-leading you!!! LOL

I agree it is not likely to be the fuel pump, since it can supply enough fuel at 3500 rpm

If it is a carby model, it may be that the idle circuit is blocked. It supplies fuel all of the time - most or all of the fuel at idle, and some up the rest of the rev range, in most carbies.

Now, this will sound a bit dodgy, but you probably won't be sucked into the carby if you do it. Start it, and get it up to a rev range where it runs, and then block off the carbie with your hand. You'll need to take off the airfilter plumbing. The idea is that the sudden vacuum in the carbie may suck out whatever is obstructing the relevant jet etc. Or not. This was recomended to me by a mechanic, I've done it and survived with absolutely no ill effects, and it is a cheap option that may fix your problem.

It occurs to me that one of the vacuum lines (thin lines going to dissy etc) may have failed, and allowing the engine to run too lean - however that ought to affect LPG as well?

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Originally Posted by Danchez

Hi guys, just thought id ask if anyone had any ideas why my Patrol runs on gas, but struggles to run on petrol. It starts fine on petrol, but then conks out. It also runs on petrol if i keep the car on high revs - 3,500+ - but again conks out when i take my foot off the accelerator. I have tried changing the leads, plugs, adding a fuel injector cleaner and re-adjusting the timing, but none of those things seem to help. Does anyone think it could be the fuel pump? How could i test it and where exactly on my car is it located?

Any help in this matter would be greatly appreciated.

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I'm going to assume that the engine is a fuel injected TB42e because you mentioned adding fuel injector cleaner.
Has this problem suddenly started or has it been getting progressively worse? And has the engine been back firing?

One problem that is very common with dual fuel (petrol/gas) powered vehicles is petrol system degradation caused by the engine running on gas the majority of the time. Petrol goes stale in the tank, carbies or injectors can block up, fuel pumps can block up etc etc. The cause of your problem could be any of these or a combination of them. A blocked injector can lead to poor atomisation of the fuel and causing poor running and sometimes backfiring. A couple of really good backfires can damage the airflow meter which could be another possibillity in your case.

As the others have already said it's unlikely (though still remotely possible) that your fuel pump is faulty because it would not be running at all on petrol. As Scott also said it could be a faulty coolant temperature sensor.

Remove the ducting between the air flow meter (on the air filter housing) and the throttle body on the inlet manifold. Have a very close look at it checking for splits and cracks that could be allowing air into the engine that has not been measured by the air flow meter. Make sure the ducting is properly refitted so no unmetered air can enter the inlet system.

Tony

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Originally Posted by Bigrig

Hey mate - don't think it would be fuel pump as it normally just dies. To test that, remove the fuel line on the bottom side of the filter whilst the car is stopped (beside the battery) and put a small bottle over the end of the fuel line to catch petrol - get someone else to turn over the ignition briefly and then off again ( literally a second or two) and fuel should flow into the bottle, if not the pump could be stuffed. You could also try removing (again whilst stopped) the green coloured transmission relay and plug it into where the green fuel pump relay is and repeat above (relays are beside/at the rear of the battery also) - this will test to see if it's the relay. If you get fuel, the relay is stuffed, if not, back to the fuel pump. The fuel pump cover is located under the carpet in the far back - you have to remove the scuff strip and roll the carpet back - but unless you know what you're doing, not much you can do there other than check the wires going to it.

That all said, again I think the pump would be fine (as such) if the car is constantly starting and then stopping under idle. Could be similar problem to what I had with mine - coolant temperature sensor is knackered as it sounds similar to the problem I had (dual fuel also, ran fine on gas, but a dog on petrol - didn't quite stall, but was close to it though). Guys on here who'll be able to narrow it down, but if it is that, it's an easy fix (and reasonably cheap - $42 I paid for the sensor). Fingers crossed!

Someone will be along with more to assist mate (Tony!!!) and he'll probably get up me for responding at all and mis-leading you!!! LOL

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For someone who likes to be the class clown a lot of the time this is a very good response and not at all misleading. Well done Scott.

Tony

Its an EFI if he put injector cleaner thru it (at least I hope so)... It can't be electrical IE leads plugs etc as the LPG is more sensitive to elec issues so pretty much has to be fuel.

By "it starts fine then conks out" how long does it run and is it only at idle and is it rough as guts? How long have you had the truck, how often do you run it on Petty and does it have Flashlube or any type of Valve Saver injection

From the info so far ... I am tipping the Injectors are clogged up and the tips eroded so I'd be tempted to get the injectors serviced

Dang Tony... we gotta stop replying over the top of each other... ROFL.

Least it gets all the bases covered... :p

Thanks for giving me a bit more of an idea of what to look out for. It seems like the consensus is the fuel pump is fine, but i think i might test the fuel pump anyway, just to be sure - thanks for the tip big rig.

Otherwise ill have a play with the coolant temperature sensor and the idle circuit.

Thanks again for all the tips and covering all bases. I'll let you know how i go.

Danchez

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Originally Posted by Danchez

Thanks for giving me a bit more of an idea of what to look out for. It seems like the consensus is the fuel pump is fine, but i think i might test the fuel pump anyway, just to be sure - thanks for the tip big rig.

Otherwise ill have a play with the coolant temperature sensor and the idle circuit.

Thanks again for all the tips and covering all bases. I'll let you know how i go.

Danchez

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I'm still curious as to when the injectors last serviced as well... look forward to updates as you go because it helps the next people who come along

Did you fix it mate?? I seem to have the same problem.
Starts and runs on gas but wont run on petrol. The turck backfired and blew up the air intake box.
Did it damage the air flow meter? How do you check this??

1: New Fuel pump and filter. Checked preasure and flow with the flow meter all within specifications
2: Checked injector cabling with CROW and see the square wave signal.

Switching onto gas switches off the pump and injectors. Going from Gas to Petrol pump starts again and the car runs a little and stops???
Any help would be appreciated.

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.

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!

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.

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!!!

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 :(

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?

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.

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Originally Posted by 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.

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Let us know how you go with this.

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.

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Originally Posted by 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.

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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.

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Originally Posted by dom14

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.

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The AC Delco parts listings had the original pump listed with a photo that was a direct match. Couldn't find a Delco pump available but the Delco book cross referenced the Fuelmiser pump number which was available, so I ordered the fuelmiser pump.
Didn't even bother enquiring about genuine Nissan parts- pricing is normally calculated on an additional 300% sucker surcharge.
Didn't expect the O ring to leak for the reasons you mentioned, but all hoses are secure and the fuel leak is coming from the O ring area - Impossible to see with the tank in place in the car.

Did you try Patrolapart? They have very reasonable prices.

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Originally Posted by Arfa Brayne

The AC Delco parts listings had the original pump listed with a photo that was a direct match. Couldn't find a Delco pump available but the Delco book cross referenced the Fuelmiser pump number which was available, so I ordered the fuelmiser pump.
Didn't even bother enquiring about genuine Nissan parts- pricing is normally calculated on an additional 300% sucker surcharge.
Didn't expect the O ring to leak for the reasons you mentioned, but all hoses are secure and the fuel leak is coming from the O ring area - Impossible to see with the tank in place in the car.

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I was able to source the pump from Burson for around $130 on mine. Also available for same price on ebay.

Your should look the same except the EFI pump is a much higher psi one.

The Fuelmiser one would've cost you over $150. Way too much fiddling while having to do all the mods to fit it in, IMO.

Having to lower the tank again is not fun at all. I would look into the possibility of creating a new access hole from the top.
I'm assuming your is an aftermarket tank, in which the original access hole is no use.

O ring leakage from the sender unit is a bit of puzzle for me.

Following.

Mine was running okay on both but would shake a bit when idling on petrol. Had a real bad backfire and the air filter housing cracked and the air flow sensor broke :( We're replacing those but would really like for this to not happen again, how can I avoid this?? Thanks guys!

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Originally Posted by ranger gus

Following.

Mine was running okay on both but would shake a bit when idling on petrol. Had a real bad backfire and the air filter housing cracked and the air flow sensor broke :( We're replacing those but would really like for this to not happen again, how can I avoid this?? Thanks guys!

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Backfire means too lean fuel mixture.
You need to find out the cause of that, be it fuel starvation due to bad injectors, bad fuel pump, etc or vacuum leaks, etc.
Vacuum leaks can be located using a spray can like WD40 & spraying into suspected hoses, joints, gaskets, etc.