Nissan GQ Patrol - Petrol problem

[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.

[Bigrig]

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.

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

[Silver]

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?

[YNOT]

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.

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

[YNOT]

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

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

[the evil twin]

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

[the evil twin]

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

Least it gets all the bases covered...

[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

[the evil twin]

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

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

[skidy04]

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.