Prinns VSI

[minkster100]

I have a 2005 Grand Cherokee 5.7L V8 fitted with a Prinns VSI system. She has covered 35K miles since the conversion, without any problems. However....... a few days back (just prior to the cold/snow spell) I ran out of LPG, the system switched to petrol and the bleeper sounded, I pressed the Prinns button to cancel the sounder and all was well. On Saturday I filled up with LPG, but when I try to switch to LPG nothing happens. The system light is on as normal, (no other lights are on) and the car is running fine, it just wont switch over. Anybody got any ideas? Is it possible that a solenoid has frozen in the bad weather? Thanks

[classicswede]

Could be the vapouriser solenoid stuck with gunk inside. Can you here the solenoids activate at all?

[woody]

If it wont even attempt to change over it could be a couple of things, as said by CS it could be the tank solenoid or wiring [is your tank underneath??] or a missing rpm signal if its been fitted with an rpm filter.

Get it plugged in by a Prins dealer it wont be hard to find the problem.

Woody

[rossko]

Won't be solenoids or gunk if its not attempting to changeover, followed by beeps and flashes.

Check engine coolant level - and antifreeze strength! If its very weaky the hoses could be full of slush.

[minkster100]

Many thanks for all of your answers. I cant hear any solenoids operating (I have checked the fuses, 3 of them and they are all OK).
My tank is underneath, in place of the spare wheel. Don't know if it has an RPM filter. As Rossko says it does not attempt to change over, when I press the button nothing happens, no lights on or off no buzzers, nothing at all. Rossko - I will check the coolant level tomorrow, the car has had a slight coolant leak since the day I had it, I have had to top up the coolant regularly over the years I have owned the car, therefore, I have to assume that the anti-freeze mixture is diluted. What is the relevance of low coolant level on the operation of the Prinns system? Thanks.

[Gilbertd]

It won't switch over until the vaporiser is up to a pre-determined temperature. The flow of coolant through it is what raises the temperature so if the coolant level is low or insufficient antifreeze means it has turned to something resembling slush, then there will be no flow and it never will switch over.

[rossko]

when I press the button nothing happens, no lights on or off no buzzers, nothing at all

the orange light should switch between dim and bright when you poke the button. Bright is waiting to change to gas. If that's not happening, your button press is not being acted on. Later versions will pip-pip as well to acknowledge, but I guess yours never has.

Be careful with weak antifreeze, this can do some damage or lead to unexpected boiling over (counter-intutive, but slush can form in radiator chilled by the wind, blocking flow, and the engine boils) -10c forecast for parts tonight.

[minkster100]

Hello All

Update on the problem with my LPG system. I drained the coolant, flushed the system and refilled, but it made no difference. It was money well spent though, as the coolant was past due a change.

Today I took the Jeep to Hilton Autogas Centre at Featherstone. They quickly diagnosed a fault with the Prinns button in the cab. Whilst is was there I decided to have them service the system as well. I have previously read many good reviews about these lads, and was impressed when two of the techs took the time to check over the installation and talk me through its various features.

Many thanks for the help.