V70 bi fuel help

[v2brett]

hi guys a friend of mine has a factory bi fuel v70 which has covered over 200k but for the past year or 2 the car will cut off Gas after a period of time.
the car runs longer on gas in cold winter temps and can also be made to run on gas for longer with the heaters on full but will eventually cut off gas.
strangely though a few weeks back it came all way back from london to yorkshire without a hiccup on the gas.

just wondered if any of you lpg gurus have any advice for him and whether it would be expensive to sort


thanks

[reggit]

Intermittent fault in one of the shut-off solenoids coils, usually the front one, will be a suspect, the plastic cover cracks with age and heat cycles.

However I had intermittent LPG running issues on mine when I first got it (at 82,000) it turned out that this was the LPG stepper motor - but it also brought the check engine warning light on - the stepper motor fault showed up on vida, so if you can get the codes read on vida it will give you a good idea if the stepper is the cause or not.

[Pete_c20]

Originally Posted by v2brett

hi guys a friend of mine has a factory bi fuel v70 which has covered over 200k but for the past year or 2 the car will cut off Gas after a period of time.
the car runs longer on gas in cold winter temps and can also be made to run on gas for longer with the heaters on full but will eventually cut off gas.
strangely though a few weeks back it came all way back from london to yorkshire without a hiccup on the gas.
thanks

Hmmnn. Sounds like something to do with the car not being able to loose heat. On all 3 instances there - winter temps/heaters on full/long straight runs the car has the ability to loose more heat than by its fan alone. What do you do if you've got a partially failing cooling system and you can't stop? stick the heating on full and don't idle in traffic.
I would do some basic checks, maybe coolant level and cooling fan operation. And yet it runs okay on petrol? Hmmn. Burning LPG takes more heat out of the coolant system as the vapouriser absorbs it to vapourise the liquid LPG.
The only other thing I can think of is that some vapourisers of factory fit Volvos have a temperature sensor on them. This instructs the car to flip over to LPG once the coolant temp rises above about 15 deg C (i think!). It's the only wire that will go to the vapouriser so easy to tell if yours has one. I wonder if you've got one and it's gone dodgy?

[v2brett]

Cheers for the replys guys, coolant level and fans are ok and the car runs fine on petrol.
could you tell me a rough cost on these parts so i can tell my friend.

would the temp sensor be hard to check?


thanks

[Pete_c20]

At a guess the temperature sensor is an NTC (negative temperature coefficient) thermistor but I'm not certain. If so, its resistance will fall with rising temp. One end of the thermistor is grounded by it being screwed into the vap housing and the other end of it is connected to the wire. You'd need to measure volts with the meter across the vap housing and the wire and expect to see the voltage reading failing with temp. At least that might tell you if it works and does roughly the right thing.
(NB that makes some assumption about the thermistor's driving circuitry but its a fair guess)
For a better test you'd need to know what its characteristic is supposed to be (ie resistance vs temp) and pull it out to test it.
Do let us know how you get on, especially if you fix it!

Which prices do you mean?

ETA: I'd measure mine for you but I aint got one!

[glider]

I agree with Reggit; the stepper motor in the gas distributor is a common culprit in BiFuel models. I've had a 2003 S60 BiFuel for 6 years, and in that time had the gas distributor changed, then 3 years later cleaned out, plus a new stepper motor fitted. It runs fine now, but any work on the lpg system won't be cheap.

[CNGBiFuel]

Stepper Motor, stepper motor and stepper motor. Either gunked-up or mashed (via the gunk seizing it), or dry solder joints that show themselves when hot. Whip-off the stepper motor end cap and resolder.

Stepper motrs are not cheap. The item is Volvo only, you cannot fit the Vauxhall version at £40, yours is the 'bunced-up' Volvo one at £300+

I keep meaning to try the PCB off a Volvo one on a Vauxhall motor, I'm sure the only differnce is the circuit being 5 pot.