Gas/Petrol Issues - can't run on petrol now after switching from Gas to petrol?????

[Twitch78]

Hey guys,
So I have been away from Canberra to the Gold Coast, and just back now. The trip down was great however on the way back I ran into some big issues. I have a 4.5ltr 99 model GU patrol with Gas and petrol. When we were travelling the car started to splutter as I ran out of Gas so I hit the petrol switch to keep going. a few seconds in I noticed that it started to stall so I backed off and pulled over. I noticed that at about 2 and a half thousand revs it would stall and a few minutes later it went down to 2, 1.5, then 1 thousand and then if I hit the accelerator at anything over idle it would stall. When the NRMA came it would barely start and they towed it to the petrol station. The Gas runs fine with it but if I switch back to petrol it stalls immediately now.

I have been told that it may be a fuel pump from a friend, however NRMA seems to think that it may be an air flow sensor that has blown. Apparently I need to have the revs at idle when switching between petrol and gas and that may be why the sensor has blown.

I really don't know. Either way can anyone help with what to look for? Can I test the Air flow sensor to see it it's knackered? If it is the fuel pump it sounds a little funny, but can I test that too?

Cheers,

[GQ TANK]

Sounds like partially blocked fuel filter, its letting a trickle though only.

[Bob]

Mine sometimes does the same thing and all I do is disconnect the Battery (to reset the ECU) for 10-15 minutes

[my third 256]

how often do you run a tank of petrol through the motor sounds like you have dry seals and gaskets in the carby
or efi unit my 4.2 efi did it until they replaced dry gaskets too much running on gas only

[threedogs]

If they suggested the MAF it may be worth while fitting a catch can, or simply carry some MAF sensor spray.
Does sound like its starving for fuel, its not dual fuelling is it

EDIT:::: is the gas/fuel switch switching ???

[Twitch78]

I run both fuel and Gas, I have only bought it 2 weeks ago though so I can't speak for the other owner.
Where would I find the fuel filter?
Is the MAF easy to locate?

[Twitch78]

yeah it does switch, as soon as i switch it dies

[Bigcol]

also - if your "that way inclined" check ALL of your earths - coil packs etc

mine had that sort of problem, and we finally traced it to a faulty earth on the Electronic Ignition
your petrol needs the best spark it can get - the gas is not as fussy

cheers

[Twitch78]

ok so I disconnected the battery, still no luck. When I switch it to fuel it stalls. If I turn it over it just won't start

[Winnie]

Is there definitely petrol in it? Don't rely on the fuel gauge. My mate chased petrol problems for ages in his GQ, ran fine on gas but very similar symptoms on petrol. Turned out his fuel gauge was showing half full when really there was no petrol in it haha

[Twitch78]

Um yeah, a full tank of premium!

[Twitch78]

If they suggested the MAF it may be worth while fitting a catch can, or simply carry some MAF sensor spray.
Does sound like its starving for fuel, its not dual fuelling is it

EDIT:::: is the gas/fuel switch switching ???

Hey what would be the reason for a catch can? Also can I check if the MAF is stuffed? Where would I buy another one? Can I fit it or does a mechanic need to do it?

Cheers

[my third 256]

here is the position and mudski is the chap
http://www.nissanpatrol.com.au/forums/showthread.php?18626-Mudski-s-MAF-Sale
http://www.nissanpatrol.com.au/forums/showthread.php?597-Checking-and-cleaning-MAF-sensors

[threedogs]

The catch can will prevent to MAF sensor fouling up
as all oily fumes will now go to the catch can.

[altech]

The catch can will prevent to MAF sensor fouling up
as all oily fumes will now go to the catch can.

Hi Guys , doesn't twitch78 have a petrol motor ?

[altech]

Hi Twitch, mine had some trouble few weeks back with switching to lpg, so the auto elec guy made it so it ran on fuel and the old story of lpg/pet is you have it turned one or the other , so on the way home the GU had no power when putting foot down, but was running slow , pull over and adjusted the distributor by ear ,found that where distributor markings was in centre ,turn it all the anti-clock wise and now the motor is running great. maybe the same with you regards Alex

[Twitch78]

hi guys , doesn't twitch78 have a petrol motor ?

yes..........i do!

[Twitch78]

Hi Twitch, mine had some trouble few weeks back with switching to lpg, so the auto elec guy made it so it ran on fuel and the old story of lpg/pet is you have it turned one or the other , so on the way home the GU had no power when putting foot down, but was running slow , pull over and adjusted the distributor by ear ,found that where distributor markings was in centre ,turn it all the anti-clock wise and now the motor is running great. maybe the same with you regards Alex

Hey thanks for the info, the switch is fine though. When it switches to LPG it runs fine but now when it switches to petrol it stalls - foot down or not, it won't even idle now. It only happened when I ran out of GAS and switched it to petrol, 10 seconds later it spluttered over 2500 revs, then 2000, then, 1500, then 1000, then anything over idle, then it stalled at idle and now it won't idle. It almost starts but it won't. But on LPG its perfectly fine.

[mudnut]

Okay, test the back of the lpg /petrol switch for power to either side when switched. If power is there, then check for power at the fuel pump. (on a GQ that is under the carpet in rear cargo area. There is an access cover. However, it could be different for your model.) If there is power, check for fuel after the fuel filter. (Using the appropriate steps listed in the workshop manual)

[4by]

Mine did the same with petrol and lpg.
Can you put your foot flat on accelerator and start it on petrol and keeps revs above 2500???? Or rev it up on lpg and switch it to petrol keeping revs above 2500??? If it does run then stalls my bet on maf.
Ended up fitted second hand air flow meter and all good now. Car will run on lpg as it doesn't read via air flow but not on petrol.
Air flow meter is located just after air filter box. Its black square box with 2 screws ontop bit smaller than cigarette box. Ill try and send you a pic of the instructions tomorrow. Im on holidays but I think I have a copy in the car.

Or you can download the user manual and instructions will be there how to test it.

[Twitch78]

Mine did the same with petrol and lpg.
Can you put your foot flat on accelerator and start it on petrol and keeps revs above 2500???? Or rev it up on lpg and switch it to petrol keeping revs above 2500??? If it does run then stalls my bet on maf.
Ended up fitted second hand air flow meter and all good now. Car will run on lpg as it doesn't read via air flow but not on petrol.
Air flow meter is located just after air filter box. Its black square box with 2 screws ontop bit smaller than cigarette box. Ill try and send you a pic of the instructions tomorrow. Im on holidays but I think I have a copy in the car.

Or you can download the user manual and instructions will be there how to test it.

Ok, so when I run the car and switch it to petrol i get a couple of seconds (probably enough for it to kick in) and then it dies. LPG isn't on the air flow I don't think.
I looked at a small black 2 screw fitting, it had a few wires going to it that can be unclipped. It has a shaft about 5cm long with 2 small filaments. Kind of like a light bulb with no glass. It looked in tact but not sure how to test it - if that is the MAF (Air flow sensor?).

Anyway ANY help is appreciated THANK YOU!!!

[threedogs]

Have you tried it a few times on the run sometimes if you just fill up on gas you'll get an "air lock"
flicking to petrol/gas a few times clears it

[Twitch78]

I run on both petrol and gas.
It ran for 5 minutes on petrol but stalled over 2500 revs. It gradually decreased to 2000, 1500, 1000 and then at idle and now it won't run on petrol at all. Its not an air lock.

[threedogs]

Can you disconnect the fuel solenoid and see if its pumping fuel.
My mate who does gas conversions says 99% of problems are 12V related.
You are not getting fuel so either the solenoid not switching properly, or no power to fuel pump.
Just throwing stuff out there, I'll re-read the lot again.
Has to be a bad earth or a wire has come off, fine on gas.
Gas likes it a tad advanced, just shy of pinging on petrol
grab your multi meter an start checking for power on all the petrol switching solenoids,
MAF has values of low volts not sure until a find my manual

[4by]

Ok, so when I run the car and switch it to petrol i get a couple of seconds (probably enough for it to kick in) and then it dies. LPG isn't on the air flow I don't think.
I looked at a small black 2 screw fitting, it had a few wires going to it that can be unclipped. It has a shaft about 5cm long with 2 small filaments. Kind of like a light bulb with no glass. It looked in tact but not sure how to test it - if that is the MAF (Air flow sensor?).

Anyway ANY help is appreciated THANK YOU!!!

Yes thats the maf. Dont touch the wires at the end. Ive sent you a PM.