940 having intermittent difficulty starting

[Laird Scooby]

Originally Posted by Laney760

One other thing? We had the petrol injectors unplugged from the injectors and she was running on gas, running well. I picked up one of the unplugged injector leads to take a look at it as it looked a bit ropey (the furthest one back) and that very second that I was handling it the engine stopped dead? Can't see any logic to this other than coincidence? Yet why she stop for no reason, she just doesn't do that.

That lead would bear investigation Ellie, especially if that's where they've picked up the connections for the LPG. If it won';t start easily tomorrow, try wiggling that lead again and see what happens.

By the way, does it seem any different driving it with the new CPS fitted?

[Laney760]

Originally Posted by Laird Scooby

That lead would bear investigation Ellie, especially if that's where they've picked up the connections for the LPG. If it won';t start easily tomorrow, try wiggling that lead again and see what happens.

By the way, does it seem any different driving it with the new CPS fitted?

Cheers Dave, will do

On my way home, running on gas, I did think that she felt 'smoother' so then I switched to petrol to see if I felt any difference and then I just couldn't think or feel anything any more, it's been a hell of a few days for me, then I gave up thinking about the car and started worrying about other things!

[Laney760]

I'm really happy that I've replaced this crank sensor, just look at it! Also really happy that I've replaced the engine coolant temp sensor because the code read that was faulty and since the new one was fitted the code has cleared. So I don't mind that I've spent money on two parts that didn't solve the starting problem!


008 by Strider'swoman, on Flickr

[Laird Scooby]

Originally Posted by Laney760

On my way home, running on gas, I did think that she felt 'smoother' so then I switched to petrol to see if I felt any difference and then I just couldn't think or feel anything any more, it's been a hell of a few days for me, then I gave up thinking about the car and started worrying about other things!

I'd say you made a good call on the CPS then Ellie, from your comments about its appearance and the improved running, especially on gas (which is where ignition-related faults tend to show up first) it would seem you caught it just in time before it let you down.

Have a look at Pg90 (by document viewer page counter) of this pdf Ellie :

http://www.myvolvolibrary.info/Tech_...ction-3-39.pdf

It shows a LHD car but given the injection ECU is in the right hand footwell, it's probably in the same place. You're looking for connector C55, an 8-pin connector and the grey wire in that is the -ve signal to the injectors. If the connections are dirty/corroded or otherwise not making well in that plug, it could cause the problems you're having, if the garage is right and the -ve is disappearing from the injectors. Also from what i can make out, the grey wire from there runs across the bulkhead as part of another loom into the rear most injector and then lopos from there to the others. That would tie in with your experience earlier with the #4 injector plug when it suddenly stopped.

[Laney760]

Originally Posted by Laird Scooby

I'd say you made a good call on the CPS then Ellie, from your comments about its appearance and the improved running, especially on gas (which is where ignition-related faults tend to show up first) it would seem you caught it just in time before it let you down.

Have a look at Pg90 (by document viewer page counter) of this pdf Ellie :

http://www.myvolvolibrary.info/Tech_...ction-3-39.pdf

It shows a LHD car but given the injection ECU is in the right hand footwell, it's probably in the same place. You're looking for connector C55, an 8-pin connector and the grey wire in that is the -ve signal to the injectors. If the connections are dirty/corroded or otherwise not making well in that plug, it could cause the problems you're having, if the garage is right and the -ve is disappearing from the injectors. Also from what i can make out, the grey wire from there runs across the bulkhead as part of another loom into the rear most injector and then lopos from there to the others. That would tie in with your experience earlier with the #4 injector plug when it suddenly stopped.

Cheers Dave. I'm very very busy in the run up to my holiday so if I don't get time to investigate further I'll print off these posts and give them to my garage!

[Laney760]

Whats the wire that runs parallel to the driver's seat, its tucked under the trim. Just before this problem started I tucked that wire back under the trim, then thought that was stressing it too much and then left it outside of the trim? Doubt it's anything to do with it, but just in case?

Edit, will post up a photo tomorrow

[Laird Scooby]

Originally Posted by Laney760

Whats the wire that runs parallel to the driver's seat, its tucked under the trim. Just before this problem started I tucked that wire back under the trim, then thought that was stressing it too much and then left it outside of the trim? Doubt it's anything to do with it, but just in case?

Edit, will post up a photo tomorrow

Errrrr, pass! That's one of those "piece of string" questions i'm afraid! Could be anything, not sure the photo will help but it might. Could be seat heaters, a wire added for something like the gas solenoid or possibly the signal wire for the LPG tank level sender. Doubtful it's anything to do with the injection but depending which piece of trim you mean, it could be.

[Laney760]

Originally Posted by Laird Scooby

Errrrr, pass! That's one of those "piece of string" questions i'm afraid! Could be anything, not sure the photo will help but it might. Could be seat heaters, a wire added for something like the gas solenoid or possibly the signal wire for the LPG tank level sender. Doubtful it's anything to do with the injection but depending which piece of trim you mean, it could be.

Sorry, I thought you knew EVERYTHING! :-) You know SO much, I thought you knew everything! :-) I'll post a photo tomorrow

[Laney760]

Great news!

Came out this morning for my first cold start of the day, she ROARED into life as every self-respecting red block should do first turn of the key, none of the previous issues so I thought ''yay, the cold starts are resolved and now just the hot starts to resolve''. Came out of work, a cold start, she roared into life again! Restarted her four times, every time so easy!

Stopped in Tescos on the way home, wondered how the hot start was going to be after I came out of Tescos, expected it to be a little stubborn. First cranking, with no gas, WAS a non starter but every one after that with full throttle was successful, time and time again no problems with starting. Came home, switched off outside my garage, loads of hot starts, one after the other, no problems. Not sure why she now needs full gas on hot starts but provided she gets full throttle she fires into life immediately. She is in for throttle body clean on a big service in a few weeks time anyway so I'll see how she is after that.

A huge thanks to everybody for all their input, particularly to Dave who has an absolute wealth of knowledge about my car!

Edited to say that after the fitting of the new crank sensor at the garage yesterday I think I was trying to hot start her immediately afterwards with no gas but anyway, all is ok now!

[Rversteeg]

Congratulations, I think you are almost there!
It should not be necessary to hot start with full throttle. What happens if after a successful hot start with full throttle you immediatly switch her off again and restart without touching the throttle pedal? If it does fire a second time without throttle I suspect the inlet manifold had filled itself with LPG. With full throttle you clear the overrich petrol/LPG mixture out quickly.