10yr old PRINS system on 4.0 Jeep - Cutting out at speed

[strange_days]

Yes the battery had definitely gone flat or been disconnected, as I had to do the radio code.

It's suddenly today got a lot worse now, it runs like it's misfiring or dropped a cylinder, even though fine on petrol. On gas it won't rev over 2k and won't run more than 20 mph. It's been backfiring a lot too...

[rossko]

Yup, it won't fix itself by being driven around.

It is possible for an out-of-sorts gas system to cause a backfire in use. It is possible for a backfire to cause more problems, from a simple pipe blowing off to real damage like rupturing the diaphragm in the vap. Not only won't it get better by itself, it can get much worse.

[strange_days]

You could fit a leonardo for example as the lambda controller and see how the vap copes. It wouldnt take long to do as all the inputs you need would be there, biggest pain would be fitting a new switch. I dont know this because its been many a moon since ive fitted anything prins, i used to a lot back in the early days, but on an italian system it would point at the rev sens from the coil causing that kind of thing, its the safety wire so to speak, if its loosing its feed from the coil the ecu sees that as the engine not running and will switch back to petrol and turn off the solenoids so its not chucking gas down the inlet with no spark or running engine ? just a thought.
Where are you, i would be happy to quote you for such a job if you arnet far from me. If you are it probably would be more cost effective to find someone closer, especially as you are on petrol !

I'm in Crodon

Thank you for all the info though, it's hugely appreciated!

As in Croydon ? By any chance.

Well, I should like to thank Toby (Tubbs) for all his efforts and a job well done. Toby set my expectations on price, came down and fitted a new system for me.

It turns out the problem was the rear solenoid malfunctioning, but I'm glad to have a new system anyhoo. Is running very nicely.

Thank you Toby!

[Tubbs]

I would just like to point out that I actually diagnosed the tank fault BEFORE I fitted the new system. But Simon decided he would rather have a new vap and Leo anyhow. Unfortunately it was going to be a strip down, tank change as it had no shut off tap. As I was in the street in south London, there was no way I was draining a tank full of gas In the street to change the solenoid plunger. Not with drains and the like. So he ran it up to my mates unit in Cambridge, where I was planning to change the tank. When I dropped it, it transpired to be a 2007 4 hole stako tank anyway. So I drained it safely (no drains, big empty field) and changed the solenoid guts. So I'm glad that you are happy, there was no way I wasn't going to sort it once I had done so much !