engine stalls when it switches to lpg, trys but stalls.

[robbie1003]

good morning, or not so good for me. I have a jeep 4.7 v8 with the romano multipoint system on, lastnight while otherhalf used it for work she says it lost power, the switch alarm went off and car switched to petrol and was then ok. it does this everytime you switch to gas, immediate loss of power,alarm, switch to petrol, if you switch it to gas it looses power and goes to petrol. can anybody shed some light on this please. the tank was filled yesterday so isn't empty. infact I have just tried it myself and if you switch it to gas it just seems to die out and stall, starts and runs ok on petrol. thanks

[robbie1003]

And if anybody has recommendations for parts suppliers please.

[Gilbertd]

Tinley Tech stock, or can get, most items. See http://www.tinleytech.co.uk/acatalog/tt-shop.html

Have you worked out what the problem is? I suspect nobody has answered as there are a number of things that could the problem. It might be low coolant so the reducer is not getting hot, it might be a failed solenoid so no gas is getting through, it could be just about anything.

[robbie1003]

Hi,thanks for that. No,still have problem, can't do much till I get home this evening,had 10mins with it this morning, Deffo not low coolant, reducer is hot and no sign of freezing up. Im suspecting solanoid but just wanted some feedback on the fault so i had some direction to go in. Typical it has a full tank of gas the first time we have problems. Can the under bonnet solanoid be removed without loosing all the gas?

[kbs]

Before removing solenoid - check battery voltage is present at the solenoids whilst the system is trying to change over. Note that this may only be present for the few seconds that change over is being attempted. Once the system gives up (trying to run on gas) the solenoids should close.

Most likley one solenoid on tank and one on (or near) evaparator. You can often hear the mechanical noise of the solinoids opening.

Check the voltage with the solenoids still attached to the wiring as testing the wires whilst not attached can show full battery voltage which may dissapear as soon as the cabling is put under load.

You can also check the soilinod coil resistance but some incorperate a diode so not all meters will give a correct reading.

If you do find the coil winding has failed - this is often available separatly and it may be possible to change it without opening the gas circuit.

If you are happy that it is safe to loose some gas into the engine bay - Depending on the type, it may be possible to open a filter housing on the front solenoid and hear gas flowing into the engine bay when trying to change over.

Whilst it is normally possible to remove the front solenoid and only lose the gas in the pipe between the front and rear solenoids (after removing power connections to rear solenoid) - it would be irresponsible for anyone to suggest you do that without first proving the rear solenoid is present and operating correctly, even then it would only be a temporary measure to diagnose a fault.

[robbie1003]

Ok,thanks for that. We do have a LPG recovery tank at work (not been used in a long while tho),might be a idea if I take car to work and try and get gas out,atleast i can do the diagnostics at home a bit safer. It is atleast attempting to run as i first thought it could be temp probe problem but as far as i can workout it wouldn't try to switch if it was. Just a thought, can I check these solanoids when car is cold as it obviously won't want to change over, I presume holding the dash button in for 9flashes would overide it?

[kbs]

Sorry, I don't know about starting that system on lpg. Probably a question for the manual or one of the pro installers on this forum.

I'd really suggest checking the basic electrical stuff (power to solenoids and continuity of the windings) before opening the gas system. If it is just a failed solenoid coil (I've had that happen twice in 5 years) then there may be no need to release any gas.

[robbie1003]

If you hold in the switch on the gas level indicator on the dash,switch ignition on,hold for
9 seconds you can start on gas.i believe its used for emergency startups if your out of petrol. Im presuming if I do this to check solanoid I won't have to wait for car to be up to temperature for the solanoids to activate. I will try and have a look at it tonight. Thanks for the suggestion.

[robbie1003]

Ok, gets home tonight to check things over, had to pull the jeep ( the car with the problem) out of drive to get my mg out so otherhalf had something to go to work in. Thought I would pop up to local garage to put a bit of petrol in jeep to get makesure I had enough for the starting and stopping, went and came back and jeep switched to lpg with slight cough but then stayed on lpg, strange. started and stopped jeep and it again went on lpg ok and stayed on it.seemed pointless checking 12v at coils at this stage as all was ok. There is a solanoid on tank so undid battery to remove the under bonnet solanoid to just check for any obvious problems, checked operation of the coil with 12 volts and it worked ok,checked resistance 12.4ohm, have nothing to say what it should be bit I though I would check anyway. Fitted all back together and all seems find. I did inspect the tank solanoid, removed the 7mm nut holding the coil on and its well and truly stuck, can't remove its plug as its held in by the coil to the spare wheel well, the metal work on the coil is well rusted but didn't want to force it off at this stage. Just let otherhalf take jeep to work and back to see if it behaves itself, don't know about you lot but the tank solanoid might be the problem? Its all Romano kit,the front solanoid,the tank fitting and solanoid. Anybody know what resistance a 12v 8w coil should be? Can't see any marking on the tank solanoid other than Romano.

[rossko]

Rusting on the outside of the solenoid has no effect on the smooth workings of the innards, no clue there.
12-16 ohms is a reasonable reading.
It's more often the front solenoids that stick as they are prone to deposits building.

[kbs]

As Ross says – your resistance value doesn’t indicate a problem. However, it doesn’t tell us all is OK either. Coils that are failing often only do so after having been warmed up (another possible reason why front evap mounted solenoids fail more often than rear tank mount ones?)

It’s not uncommon for the coils insulation to break down so that there is no longer enough magnetic force to reliably open the solenoid. Hopefully this will be indicated by the coil being more than warm to the touch.

If the corrosion is just the exterior bracket that holds the coil to the solenoid – that’s OK providing the corroded metal hasn’t expanded to the point where the coil housing has cracked. The stuck terminals also cause concern (in case its corrosion of the terminals) – you need clean low corrosion connections for this to work correctly.

Hope it keeps running!