Thread: Not running on petrol

Originally Posted by Hucksta

Hi all,

I have a D1 V8 that I converted to gas about 3 months ago. Apart from some teething problems it has been running ok. Yesterday I flicked it over to petrol and it is running like crap.

It runs fine on gas so I have pretty much discounted an electrical fault. The fuel in it should be ok as I ran it on the same petrol a few days ago. I replaced the fuel pump about 12 months ago so that should be good ok although it runs like it is being starved of petrol. Fuel filter is not that old but I might check it anyway. It chugs along like it is running on about 4 cylinders when i flick it over.

I had a search on the forum but didn't come up with much. Does anyone have any suggestions on what I should check or replace ..........

Hucksta

This MAY be the problem, (depending on how they have wired up the injector pulse cancellation, ) the Airflow meter may have sent a faulty message to the ECU when you switched from gas to petrol. To check this, leave the vehicle switched over to petrol, switch off the engine and wait for 20 seconds, until you hear a relay click under the dash. Restart the engine and if it then runs OK, the wiring is the problem. Basically, the act of switching from gas to petrol is interrupting the signal from the airflow meter,causing a 'soft' code in the ECU which makes the engine chug and run rich.
I have seen an LPG installation in a D1 wired like this. It may not effect other vehicles, but if you wire a 14CUX system up this way it will bring on a fault code and make it run like that.
JC

My V8 had the same fault, but it was extremely rare to flick to petrol on the move so it just wasn't at the top of the food chain for me. I just stopped the car & restarted it on petrol as needed. I can't drive more than 350km without a leg stretch anyway [and at that time I smoked heavily].
There must be a few around Brisbane with the same issue as it was a popular shop that did my conversion.

Thanks for your replies ...

JC,

I went and tried your suggestion. Istarted it and was running on gas, I swithced to petrol and straight away it went chuga chuga put put and stalled. I switched the ignition off and about 6 seconds later heard a click under the dash, I think from behind the steering whell somewhere. Anyway, It would not start on petrol, I tried this a few times.

I then flicked it back to gas and it started, but not without a few seconds, it used to start on petrol immediately. I then flicked the gas/petrol selector to the neutral position, the car usually runs for about 4 or 5 seconds then stalls through lack of gas. Well this didn't happen, it just kept running as normal, this is strange, it should stop. this happened every time I did it .... something wrong man.

I flicked it to petrol ... chugga chugga put put .... go through the same process and same thing .... runs on gas while gas selected and also runs on .. 'whatever' while in the neutral position.

What do you think is happening to my poor D1 .... ????????

aha now that is running rough because it is running on both fuels. As you have noticed the LPG system is not switching off. Check the black relay near the convertor with a green LED light

Thanks Dan

I was thinking the same thing after re-reading my own post .... um, excuse my ignorance but i'm not sure what you mean. Are you talking about the gas converter (the round thing) under the bonnet and I'm also not sure what the black relay is.

I will be taking it back to the gas bloke, this will be the 4th time I've been back and It is starting to annoy me real bad ..... and an annoyed Hucksta is not a pretty thing for any one ....

If there is something easy i can do then i'll give it a shot, otherwise it is back to the shop ....

Cheers

Jason

Take it back to where you had it done but tell them on the phone that it wont shut off the gas and you suspect its the relay. Depending on how accessable the relay is, its a 5 min job.
The relay, if you want to replace it, is the electrical box type device about 25mm square. Its usually near to whatever it switches, in this case a ( lpg) fuel cut off valve. Trace the wire from this switch on your LPG line back to under the dash as it sounds like the relay is there.
Could even be a wire disconnected.
Good luck