Fuel pump or fuel reg

[Jimbo]

My fuel injected tb42 gq has never really run properly on petrol. I replaced the fuel pump a few years ago and it seemed to run better but now its crap again.

The other day i decided to clamp the fuel return line........patrol now runs perfect on petrol.

Is my pump or reg stuffed?? How do i test?

cheers

[brads4wdmad]

Hi mate
I currently have exactly the same problem
I also replaced my fuel pump approx 10 months ago
My car runs perfect on Lpg but not on petrol!
I just replaced my fuel reg with a brand new one from Nissan at a cost of over $300 and it did crap all!!!

I disconnected the air flow meter and it doesn't change the idle or revs either on gas or petrol and i believe that it should go to stall when this plug is disconnected so i am thinking of the lines that in my case and just maybe yours that the air flow mass meter may be the issue
Not saying it is but its possible

[Jimbo]

I changed my airflow metre a few years back which did nothing. Now that i have clamped the return line it runs great

[neilpatrol]

The problem is they get addicted to the lpg, like a engine with aerostart. If you put a restrictor in the fuel return you shouldn't have too many more problems, just keep running it on petrol and see how u go.

Neil.

[PGS 4WD]

The pump is the likely fault, rarely do regulators fail, it also may be partially blocked injectors. Put a fuel pressure gauge on and drive around the block, the fuel pressure should go up as you accelerate. Often you will get improved performance by blocking the return line if the injectors are partially blocked but by raising the fuel pressure you will likely damage the pump if you exceed its operating pressure, also as the pressure goes up the voulume drops and it will likely lean out at higher revs and load.

Joel

[mkpatrol]

My fuel injected tb42 gq has never really run properly on petrol. I replaced the fuel pump a few years ago and it seemed to run better but now its crap again.

The other day i decided to clamp the fuel return line........patrol now runs perfect on petrol.

Is my pump or reg stuffed?? How do i test?

cheers

Regulator or injectors, this is one of the quikc diagnosis methods we used to use when injected cars had rubber fuel lines.

BUT get yourself a fuel pressure guage & diagnose it correctly.

Check fuel pump pressure, fuel pump flow & how the pump holds line pressure (they have a valve in them) just to eliminate it first.

The thing you are looking for with the regulator is line pressure drop, it will drop quickly if it is faulty and will not hold line pressure. Clamp the return line off & if the pressure remains then the reg is faulty.

If you clamp it off & the pressure drops slowly the injectors are leaking (provided you have eliminated the fuel pump first).