VT Won't run on Petrol.

[bec.ryan]

Hi all, I'm new to this forum so sorry if this has been previously covered.

I have read most the posts and tried what they suggest but still no luck, any suggestions would be appreciated.

Summary of problem so far.

VT V6 2000 Series II Acclaim.

Suddenly ran rough on petrol and limped home. Won't run at revs. Most times wont start and if it does idles roughly.

Runs fine on LPG.

Problem occurred first time two days after alternator failed (bearing and it got very hot) loom under alternator with silicon leads smoked.

So far have replaced
1.fuel pump
2. Alternator
3. Throttle position sensor.
4. Cleaned MAS with CRC MAS Sensor cleaner.
5. Fuel pump primes on ignition start.
6. Fuel pump draws 7amps when priming.
7. fuel is only two weeks old and ran fine each morning and afternoon when starting on it.
8. Car has always runs 10km day on petrol and rest on LPG
9. Tried blocking the fuel return line to see if pressure Fuel pressor valve was the issue, no improvement.
10. Tested the fuel pump relay and it is fine. Swapped it with head light relay to be sure, no improvement.
11. Replaced fuel filter.
12.Tried unplugging MAS to see if it will start, no different.
13. Checked all connectors on IDLE CONTROL SENSOR, MAS, Crank single and TPS, no change.

I am assuming that as it runs on LPG that
1. Ignition system fine.

I am assuming that as it won't run on Petrol it could be
1. ECU
2. Injectors
3. MAS
4.Fuel pressure regulator.


A test light shows injector are firing but this dies not guarantee they are working.


Any hints would be appreciated, I'm stumped!!


Cheers

Bec

 

[inSight]

I was going to say the ignition system (leads perhaps?). No harm in trying. Just buy a service kit and see how it goes.

Holden V6 Commodore VX Major Service KIT | eBay

I have no experience with LPG so if it's working perhaps it's not the ignition system.

 

[dirty hands]

a guess

would the switch to petrol/LPG be faulty

like does it give power to the petrol systems when you get off LPG

i dont know LPG either

 

[Nut Kracker]

I'd be looking at blocked injectors.

 

[cor3yz]

Blocked injectors is the obvious, but you would notice a small improvement when blocking the return line

 

[Tree cutter]

The gas might not be turning off when you try to run it on petrol, which means that you are getting both petrol and gas going into your engine so it is running too rich.

 

[Nut Kracker]

The gas might not be turning off when you try to run it on petrol, which means that you are getting both petrol and gas going into your engine so it is running too rich.

Could be....Try turning off the gas at the tank and see if it makes any difference.

 

[bec.ryan]

Thanks some great suggestions there.

I will try first to turn off the gas and see it it is running at same time as petrol this would make sense given how rough it is running.

I have had two faulty switches in past. Although this one us only a few months old. Worth a shot.

Thanks all. Any other suggestions welcome.

Thanks Bec

 

[Jxfwsf]

Doubt it'd run if both fuels were active (it'd definitely throw a rich error code if it managed).

Have you checked for error/fault codes? https://forums.justcommodores.com.au/threads/checking-error-codes-vt-vx.23665

More than likely fuel filter or fuel pump if it just suddenly happened without any warning.

 

[bec.ryan]

OK just tested the LPG / Petrol switch and found that when on LPG the fuel pump does run for petrol. The system apparently uses both when on LPG and this aspect is running fine. Petrol is used for hard acceleration on LPG and apparently for cooling / lubricant.

I switch over to Petrol and you can here the gas solenoid click off and the car stalls or idles rough, on attempt to restart you can here the petrol pump prime.

So I'm thinking that on Petrol / LPG switch is working fine.

I do here a small solenoid click on petrol under dash, I will confirm tomorrow it is working as this may be causing issues.

Thanks for the suggestion.