2003 S80 bi-fuel won’t switch to LPG
 

recently bought a 2003 s80 bi-fuel ( wife won’t let me drive the 2.5T anymore) anyway got it for a steel as the LPG system didn’t work , as I said to the wife “how hard can I be ?” Well :
1. Changed the vapourisor elbow and solenoid
2. fitted a new filter
3. Checked fuses
4. Stripped down the distributor , cleaned thoroughly and found a small piece of (possibly O ring ) stuck in the side of the stepper motor , gave it a little push and it popped out , I now know this was not a good think to do .
5. Found a faulty injector and replaced for new .
6. Checked the plugs ( they’re the multi point type ) going to change for bog standard NGK
7. Got plenty of heat circulating around the regulator.
8. Got a click sound from the boot area when operating the switch but not from the solenoid under the bonnet .
9. Tank is 3/4 full and as metioned there’s gas to the dizzy
10 . Screemed “why won’t you work” at it !

I’ve read all the posts a learnt plenty from the guys on here , I’d be happy right now if it just ran a little , even if it was rough , cut out after 10 miles , misfired , backfired or just broke wind !

Autogas 2000 have been great so far and I’d recommend them highly.

Is there anyone out there with any help , advise or similar experience to mine please ?

If the vapouriser solenoid is not clicking then have you cleaned inside it?

If clean inside then try a new coil on it
https://www.classicswede.co.uk/Bifue..._10879079.aspx

It’s clean inside and a bought a new coil from yourselves, there’s no power to it , had a multi meter on the leads and there’s no voltage when the switch is activated (engine hot or cold)

Looks like your might be best replacing teh front end for a propper system

Have you checked the solenoid operation by applying 12v from an external supply to see if it switches?

Cheers for that , I haven’t to be honest I’ll give that a go , that one should activate with the switch along with the rear one (obviously) I was wondering if the temperature sensor in the head would have to send a signal before the front one would operate.

That would make sense, but it's so long since I had a bi-fuel I can't remember exactly how it works and unfortunately the manual I have doesn't cover the bi-fuel, so I can't look at a wiring diagram to see how it should operate.

When mine was faulty, it would switch over to gas briefly before the engine died of fuel starvation, so the theory seems sound.

Ok , wired to 12v it activates with a good click ( don’t why I didn’t try that before) , so the fact I’m not getting power from the system leads me think :
1. Faulty switch ( but if fires the rear solenoid ok )
2. It needs to be up to temperature ( faulty temp gauge )
3. Faulty ECU maybe !
4. Faulty relay ( learn how to check that )
5. Faulty stepper ( not fitted right now, away being tested )

I think that’s my list complete, these are just my workings out, I appreciate guys get cheesed off with folk cribbing rather than working it out for themselves on here but having looked through the forum I’ve seen plenty of rough running and also fail after running issues but not a won’t switch over at all problems as such , could be as classic swede said “new front end “ Just need to be sure I’m not throwing the baby out with the bath water first .

If I remember rightly (and I often don't). The car will wait for the coolant temperature to reach a certain value before switching to LPG, mine used to switch within a mile - the obvious place to switch is the front (or both) solenoid/s. Can't remember where the sensor is though, some necam vaporisers have one in the body, but I think it's deleted in the Volvo installation. You need to check.

Won't be the stepper or distributer as that's after the solenoid.

Yes I’ve been told the temperature sensor on the vaporiser is not used (although fitted to the casing ) I can only surmise at this point it gets a signal from the temp gauge on the head or via the ECU (a wiring diagram would be handy) my local Volvo dealership were reluctant to pass that on to me “oddly” .
I’m working away at the moment so I’ll have another bash on my return , thanks so much for the continuing help I really appreciate it.

Just remembered, the system won’t switch if it senses a fault - so could be the stepper!

What is the light on the ‘petrol’ switch doing when you try and switch it to gas?

the stepper will throw a fault code which you can check with Vida if you have access to that.

The OP has sent me his stepper and I can categorically say the stepper is faulty. Dead-on-arrival. The OP's car could never run with this stepper.

Probably the original issue.

However I hear tales that the previous owner was a baboon. Ripped everything off the thing, now anyone's guess. There could be a heap of other probs...

Anyways, his stepper has been properly fried.
About 1 in 6 come to me in irrepairable condition. This looks like one of those. I will have another go...

I read somewhere 18 deg is the magic temperature for switch over but that would be head temperature not ambient. Mine switches within 30 secs of running even in near zero temperature.

My Necam system. On a summer's day from cold about 20 secs, at freeeeeezing about 1min 30secs.

Warm? 10 secs... ish.

Thanks for everyone’s input it’s greatly appreciated , been off grid for a few weeks , as CNG has mentioned the stepper is potentially fubar ed so progress is being made , thank you so much for taking time to comment on this for me and anyone else who my have similar issues , I’ll keep you posted of progress made .

Sit rep !
 

So now fitted a working and modified stepper curtesy of CNGBiFuel as the last one was buggered and had some excellent advice (top bloke) , but she’s still putting up a fight , still won’t switch over to LPG , been to a local garage to have it plugged in and found their system wouldn’t read the problem being an intermittent fault with the EMU relay , switched that out and got codes reading :
6310 Fuel shut off valve faulty signal
4400 Gas system fuel shut off valve , retardation
Fitted a new solenoid from classic swede but there’s no power to it nor power to the other solenoid at the base of the distributor, these both work when attached to 12v so I’m confident they’re working , its just where they take their que from that’s the baffling bit , been kinda thinking the temperature sensor but that must give information to other stuff surly ,so if that was at fault the other gubins wouldn’t function possibly, maybe or not !
Dunno, going to plug away at it some more tomorrow if nothing else I’m learning all the time and building up quite a personalised LPG owners manual from the information I’ve copied and pasted from the feed back I’ve had here (hope you guys don’t mind) , thanks to everyone’s continuing input I can’t begin to say how grateful I am .

I have a wiring diag & manual for S80 Bifuels, unfortunatley it's not in English, it's in (don't mention the war... ). Only got it a few days back, and I've not had a chance to scan or translate it. My (beach towels at the ready ) broken German can see relay FMA2 is the master power relay to all that is Necam. In turn FST02 fires the DFCO. If those relays are not firing (or the output for the CPU is not there because the temp stat is not firing an output), your car won't switch, but the fault is usually the stepper. That theory was blown sideways by a bloke I'm dealing with now. In his, he'd had some baboon of a previous owner hacking at his car.