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[D]

Well at least transiently. Ran out of LPG around half a mile from the pump, switched over to petrol (1/4 tank), spluttered, misfired and then died. Filled up with petrol and gas. Cranks, but does not start on petrol. Forced start on LPG, and she fires up and runs.

Now I have to sort out this mess before Monday and then drive 250 miles down the M1.

What a pain. What do you think? Fuel pump blocked due to a lowish fuel level(crud) or just plain dead? Have a misfire code on cylinder 1 and a pre-cat error code. I cannot imagine the misfire will prevent the engine from starting up at all.

[chrisgixer]

What are the exact codes?

[D]

0301 and 0420. At least thats what I think it was. I was a bit cold and miserable and had a cranky child to contend with. Will re-check in the morning.

[05omegav6]

Could be stale fuel... When did you last put petrol in it?

Also, has it had a crank sensor yet? Rarely shows a code...

[TheBoy]

Do you have the facility to check the trims - in case LPG has thrown the trims way off to make them invalid for hot petrol running.

[D]

Unlikely to be stale fuel. Last filled up about 6-8 weeks ago. Plus I have topped up to half a tank again.

No chance of looking at trims.

Crank sensor is original I guess. No mention of it being changed in the past records. But would crank sensor fault allow running on LPG? Would it not affect that as well?

[05omegav6]

Unlikely to be stale fuel. Last filled up about 6-8 weeks ago. Plus I have topped up to half a tank again.

No chance of looking at trims.

Crank sensor is original I guess. No mention of it being changed in the past records. But would crank sensor fault allow running on LPG? Would it not affect that as well?

I think, the crank sensor only switches on the fuel pump once the engine is running. Starting is done using residual pressure in the fuel rail whereas lpg is supplied as long as there is fuel (pressure) in the tank and both cut off valves are open.

If either the fuel pump or the crank sensor are playing up, it will never start on petrol...

[D]

And how do I differentiate? Which reminds me I need to check the relay as well.

[TheBoy]

Unlikely to be stale fuel. Last filled up about 6-8 weeks ago. Plus I have topped up to half a tank again.

No chance of looking at trims.

Crank sensor is original I guess. No mention of it being changed in the past records. But would crank sensor fault allow running on LPG? Would it not affect that as well?

I think, the crank sensor only switches on the fuel pump once the engine is running. Starting is done using residual pressure in the fuel rail whereas lpg is supplied as long as there is fuel (pressure) in the tank and both cut off valves are open.

If either the fuel pump or the crank sensor are playing up, it will never start on petrol...

Nah.

A failed crank sensor is a failed crank sensor, the petrol injectors won't fire, thus LPG piggyback systems won't fire either.

[Kevin Wood]

Yep, and the petrol pumps do prime before cranking on the 3.2.

[05omegav6]

Ah ok wrt crank sensor

Was told different when I asked about fuel pump priming on switching a couple of years ago

That said, even if the pump primes, if it's on its last legs, the pressure won't be great.

[chrisgixer]

Are you sure/could it be that, it didn't run out go lpg, but died due to crank sensor fault.

Is it worth flicking back and forth between fuels to confirm its defo only petrol at fault?

If it does prove to be petrol only, when was fuel filter last changed?

Is the eml bulb working, does it illuminate at ignition on? ....although, you don't mention a fuel trim code. Then again, 0301 would of bought the eml on, then reset on re start if the fault cleared.

More questions than answers, but does look like a petrol system fault from what you said. ....IMO.

[D]

Right, ran out of LPG, switched to petrol automatically, car spluttered and died.

Now that I have topped up both petrol and LPG, it dies on switching to petrol and refuses to fire up on petrol. Force an LPG start (ie hold LPG switch down and crank) and the car fires up. The EML is on, codes as above.

So I can potentially run on LPG all the way back down south.

No clue when fuel filter was last changed. Full Vx service was 2 years ago, presume it was changed then. Not certain though.

[Kevin Wood]

If you get it running above idle - say a steady motorway cruise, does it still drop dead if you switch to petrol?

If so, I'd say it's fuel pump related (is the fuse OK?).

If it can be made to run on petrol in this way, maybe fuel trims have gone badly enough awry that it won't idle on petrol.

Doesn't sound like crank sensor to me. It wouldn't start on LPG if that had died.

[D]

I have to say I did not try that, just wanted to get home and was worried about loosing power steering assistance. Let me give that a go tomorrow.

Could a badly blocked fuel filter cause this issue as well. May be worth changing that first.