LPG 2.1 wont run on petrol. aggghhhhhh!!!

[davec1]

I was wondering if anyone had any advice with a LPG problem I have.

My van runs so sweet on LPG, but for a time when I switch it to petrol it was running a bit lumpy, I did a full service leads plugs the lot and it ran really well on both fuels for a while.

Now, it won’t run on petrol at all, I flick the switch to change, the light changes to signify its running on petrol and it just dies.

Changed fuel filter, opened the bleed valve by the dizzy and got the fuel up, I know the there is no problem with the supply of petrol, but it just won’t run.

If I try and start on petrol it turns over nice and quickly but doesn’t fire at all.

The system for lpg is open loop fitted by GAS Sure about 4 years ago.

Anyone had similar, or anyone have any pointers for me? Really frustrating problem

Thanks in advance

[jamesandtheopenroad]

Give Steve a buzz, he's always happy to help.

[Wychall]

Not sure whether it is relevant to your engine type but I have just cured an identical scenario on my 2.5. I likewise checked everything through, ensuring that fuel was available and plentiful but no joy. I finally replaced the fuel pump and all is well. Evidently although fuel was available, it was not of sufficient pressure to crack off the injectors.

Hope this is of some help to you.

[ermie571]

Deffo ring Steve.

I have got a carb not injection 2.1, and a switch in the engine bay to manually force it to petrol only. Which is what I did when it was refusing to play ball on petrol.

Think my issue was a dirty carb - it ran, well, lumpy would be an understatment, for a while, shuddered, then took up a less lumpy feel. It does not, however, like petrol.

Em
xx

[steve8090]

Replied to your emails with technical help, please do not hesitateto call me, this was converted over 7 years ago and as far as I'm aware has never been serviced by us, if it won't start on petrol then it will not run on gas, the injected engines start on petrol then switch to gas, if all else fails I can tell you how to make it start on gas if required.

[davec1]

thanks all, printing these notes off to check again this evening

And thank you Gasure really appreciated the advise you gave me over email earlier today.

[CovKid]

There are two relays which handle the electric fuel pump, one to prime the fuel line even if running on LPG (it switches off once line is full of fuel), and the other to keep the fuel pump going when you have actually switched to petrol. Check that the fuel pump is actually running beyond priming state. Could be a faulty relay. Think they're over on the left hand side in the black box?

[Aidan]

There are two relays which handle the electric fuel pump, one to prime the fuel line even if running on LPG (it switches off once line is full of fuel), and the other to keep the fuel pump going when you have actually switched to petrol. Check that the fuel pump is actually running beyond priming state. Could be a faulty relay. Think they're over on the left hand side in the black box?

it's not like this on a 2.1 the original petrol fuel pump runs all the time even when running on gas, there's simply either a loom or a relay switched wiring bridge that effectively stops the injectors firing, the ecu is still thinks the engine is running on petrol and is still controlling the injectors and timing according to it's map (and on an MV adjusting the timing dynamically in conjunction with the lambda)

you should have at least 2.5 bar of fuel pressure at the t piece - so probably either the pump or the pressure regulator have failed and you don't have enough fuel injection pressure

[CovKid]

We'll have to agree to differ Aidan but its likely to be lack of fuel pressure and on that I think we can both agree.

[Aidan]

We'll have to agree to differ Aidan but its likely to be lack of fuel pressure and on that I think we can both agree.

I know how mine is wired and I checked with Steve how the op's was wired before I posted and there's definately no cut off on the petrol fuel pump when on gas on the 2.1 open loop systems, other installers may do it differently of course

[davec1]

does anyone know how i measure the fuel pressure? is it a job for a garage or something that can be done from home? bleed valve near dizzy seems to have some pressure behind it. The pump is defo making the same noises that its always made. checked all switches and fuses all fine. really stumped with this.

[Aidan]

you need a wet gauge that can be adapted to fit the t piece, a bit specialist, but under pressure it'll probably spurt fuel across the workshop if you turn the the ignition on for 15 seconds with the t piece blank removed or into a collection receptacle of your choice

also you can remove the injectors in pairs, still attached to the fuel rails then disconnect the king lead (coil to disi HT lead) from the disi and earth the disconnected disi end of it so there's no spark from the coil (to ensure engine can't start and fuel in area can't be ignited) then crank the engine over, observe the spray pattern and using a measuring jar (jam jar of know volume) collect the fuel for 30 secs and check the flow rate is in spec, if you have no fuel coming out of the injectors then check with Steve how to disconnect either the bypass harness fitted or the relay connection breaker and recheck

I thought you and Steve were in email contact - best solution really short of taking it up there on gas for a service

[CovKid]

We'll have to agree to differ Aidan but its likely to be lack of fuel pressure and on that I think we can both agree.

I know how mine is wired and I checked with Steve how the op's was wired before I posted and there's definately no cut off on the petrol fuel pump when on gas on the 2.1 open loop systems, other installers may do it differently of course

No, not a cut off, a two stage set up. One relay priming the line with ignition on, and the second when the engine is running. Merc Doc and I discovered this on Ronnie's camper - took us ages to find and it had already been to a couple of well known places before he brought it to us in frustration. Only way to know for sure is put your hand on the elec fuel pump and see if it continues to run when engine is meant to be idling. Once we swapped the faulty relay out, it ran perfect. Whether its standard or not I can't verify but that was the cause and it was gassed by Steve at one point.

[davec1]

I spoke with steve at gasure again a moment ago, talked over a few ideas and i explained that my local garages are a bit reluctant to work on this as itsLLPG, anyway, short of it is, he is kindly sending me a known good fuel pump for me to swap it over and see if it cures the problem. really chuffed as it would cost me £130 for a new one, and it may not even solve the problem.
i shall update you once i have the pump, hopefully it cures it as i want to get away for a few days next week!

really nice gesture by him,

fingers crossed!

[Ian Hulley]

really nice gesture by him

That's why he's a top bloke.