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[berserkerboy]

Hi folks

Having a bit of a nightmare with the LPG system on my car. Fitted by Profess LPG Ltd in 2011: AC STAG 300 by the previous owner. The car has been serviced yearly by them. Last July I had the service done but a month or so later had to return the car to them as it kept switching back to petrol. They changed a temperature sensor FOC and the car was okay until this March when the problem returned. I finally managed to get over to them today. They told me a sensor needed cleaning and that the injectors where worn out and that it would cost £330 including labour (plus VAT presumably) to replace them. So they cleaned the sensor £35 and did a service £60 which appears to involve changing the filter. The work took them about 20 minutes. The car is booked in during September to do the injectors.
Unfortunately, on the way home the car switched back to petrol again. I was annoyed as it is quite a journey to get there and I thought the cleaning of the sensor was supposed to fix this. I emailed them as soon as I got home and they responded that it was due to the faulty injectors. Would faulty injectors cause the car to switch back to petrol?
I'm thinking of getting a second opinion. There's an LPG service centre in Swansea.

[Andy H]

Switching back to petrol is usually caused by a restriction in the LPG supply eg
Blocked filter
Sticky regulator
Inadequate heat to the evaporator
Or
Inadaquate valve arrangement in the gas tank

There is a lot of experience with the stag set up on the forum. The 3.2 needs a lot of gas when it is given full throttle and short cuts taken by so called professional installers will cause problems.

[05omegav6]

Buy these...

http://www.ebay.co.uk/itm/2-VALTEK-TYPE-30-AUTOGAS-LPG-3-CYLINDER-INJECTORS-RAILS-OMVL-ROMANO-BI-GAS-STAG-/291513788009?pt=LH_DefaultDomain_3&hash=item43df936669

Fit them yourself and save £250

[zirk]

When switching to petrol does it give a bleep warning code?

[berserkerboy]

No noise. Fuel guage just rapidly blinking.

[berserkerboy]

Buy these...

http://www.ebay.co.uk/itm/2-VALTEK-TYPE-30-AUTOGAS-LPG-3-CYLINDER-INJECTORS-RAILS-OMVL-ROMANO-BI-GAS-STAG-/291513788009?pt=LH_DefaultDomain_3&hash=item43df936669

Fit them yourself and save £250

Would it be easy to do? Do I need to have access to software to calibrate them or is it a straight swap over?

[Kevin Wood]

No noise. Fuel guage just rapidly blinking.

Sounds like the temperature is beliw threshold to me, but take it somewhere who can diagnose the problem properly.

[Andy H]

No noise. Fuel guage just rapidly blinking.

Sounds like the temperature is beliw threshold to me, but take it somewhere who can diagnose the problem properly.

possibly nothing wrong with the sensor - more likely that they didn't connect the coolant hoses to the correct ports on the HBV (heater bypass valve)

[Lazydocker]

I've said it before and I'll say it again... Don't use Profess Autogas

You need to get it to someone who knows what they're doing but I agree it sounds like temp sensor. If they fitted the LPG I'm pretty confident the coolant feed to the vap will be wrong 

[berserkerboy]

I've said it before and I'll say it again... Don't use Profess Autogas

You need to get it to someone who knows what they're doing but I agree it sounds like temp sensor. If they fitted the LPG I'm pretty confident the coolant feed to the vap will be wrong 

My car switches over to gas within 200yds of leaving home. I've always thought this to be too quick, although I get warm air within about a mile.

[Lazydocker]

I've said it before and I'll say it again... Don't use Profess Autogas

You need to get it to someone who knows what they're doing but I agree it sounds like temp sensor. If they fitted the LPG I'm pretty confident the coolant feed to the vap will be wrong 

My car switches over to gas within 200yds of leaving home. I've always thought this to be too quick, although I get warm air within about a mile.

Just for giggles, turn the heater on full hot next time you go out for a drive and see if it switches to LPG ok

[berserkerboy]

I've said it before and I'll say it again... Don't use Profess Autogas

You need to get it to someone who knows what they're doing but I agree it sounds like temp sensor. If they fitted the LPG I'm pretty confident the coolant feed to the vap will be wrong 

My car switches over to gas within 200yds of leaving home. I've always thought this to be too quick, although I get warm air within about a mile.

Just for giggles, turn the heater on full hot next time you go out for a drive and see if it switches to LPG ok

I took a look at the 2 vapouriser coolant connections yesterday. One of the pipes disappears to the rear of the engine and is presumably tapped into the HBV. The other pipe comes up and is tapped into the pipe coming from the coolant header tank. Would that be correct connections?
I emailed Profess LPG yesterday complaining that the switch back to petrol would not be caused by the faulty injectors, if indeed they are?, but that the fault was more likely to be one of the ones suggested in this thread. They just replied that they couldn't comment until the car had been seen by their factory trained technician....It just has been! Have cancelled the replacement of the injectors with them.
Regarding your suggestion of driving away with the heater on full. Presumably we would expect the car to not switch to LPG as there would not be enough heat to the vap?

[Sir Tigger KC]

Do you have a coolant leak?    As that can upset LPG systems. 

[berserkerboy]

No coolant leaks

[berserkerboy]

BTW I like the Hotel California remark