Volvo 940 Starts then dies very occasionally - Page 2

Eyebrows123 · Apr 17th, 2016, 18:05

So, I finally got to look at my car today and got to the fuel pump relay (it's the big white one right?) and could remove it but couldn't figure out how to remove the whole relay assembly so couldn't really see whether any joints needed attention or not.

I had a look at the rev counter whilst cranking, it did nothing for the first 1 second of cranking then it bounced for the 2nd second of cranking then the engine started. It does seem to take a fair few cranks to start the engine though, I don't know if that is normal or not? I'll try get a video next time I'm able to get to the car if possible.

The vacuum lines all looked fine, I didn't check the T-piece with the engine running but it looked ok.

I also removed the intake pipe from the throttle body and had a look inside and it did look remarkably clean, it wasn't spotless but was pretty good, no carbon build up on the intercooler side of the butterfly valve. Didn't get to see past that though, should I have checked that?

Hope you guys can help, sorry for the slow reply.

Cheers

monkeh · Apr 17th, 2016, 19:53

I'd say crank sensor then.
10mm bolt behind the distributor on the gearbox bellhousing. Try that.

Eyebrows123 · Apr 17th, 2016, 20:04

Seen it, how do I test it or do I just have to buy a new one and swap it

monkeh · Apr 17th, 2016, 21:01

They fail either with the wiring self destructing due to its location with heat or pickup goes faulty.
Check and wiggle the wiring while its running. I tried to repair my wiring but just settled for a new sensor.

Nothing thats checkable. Just replacement...

Eyebrows123 · Apr 17th, 2016, 21:02

Ok, thanks, will have a crack at that later then

Thanks for the help, much appreciated

Rversteeg · Apr 18th, 2016, 16:49

The ECU first needs to know in what position the crankshaft is before it will start injecting and igniting. So it is normal that it takes a while before the rev counter (which is directly connected to the ignition coil) start to move. The mark on the flywheel first has to pass the crank sensor. Sometimes it is almost immediatly, sometimes it takes almost a full crankshaft rotation before it passes the sensor.

Eyebrows123 · Apr 18th, 2016, 16:53

That does make sense. But then after the crank sensor picks uo its location it does another 1-2 rotations before it'll fire. The rev counter will bounce a little which would kind of imply the crank sensor is working I would have thought? I'll have a wiggle of it next time it's running but what could be the cause of the delay of it starting? Could it be the crank sensor not being accurate or something else?

Dirty Rooster · Apr 18th, 2016, 18:31

Yeah that sounds like the crank position sensor.
10mm bolt, oily arm job. Bit like a vet with a heffer.

Eyebrows123 · Apr 18th, 2016, 18:33

Ok, might buy a replacement anyway that way at least I know it's done. Where's the best place to get one, FRF?

monkeh · Apr 18th, 2016, 18:41

Ebay... £25 tops

Apr 17th, 2016, 19:53	#12
monkeh Pain in the backside Last Online: Today 10:10 Join Date: Mar 2007 Location: Newport	I'd say crank sensor then. 10mm bolt behind the distributor on the gearbox bellhousing. Try that. __________________ 'Designed by a computer, built by a robot, and driven by a f***ing nutter' '09 XC70 SE - 2" lift, D5 225bhp, poverty spec.

Apr 17th, 2016, 21:01	#14
monkeh Pain in the backside Last Online: Today 10:10 Join Date: Mar 2007 Location: Newport	They fail either with the wiring self destructing due to its location with heat or pickup goes faulty. Check and wiggle the wiring while its running. I tried to repair my wiring but just settled for a new sensor. Nothing thats checkable. Just replacement... __________________ 'Designed by a computer, built by a robot, and driven by a f***ing nutter' '09 XC70 SE - 2" lift, D5 225bhp, poverty spec.

Apr 18th, 2016, 16:49	#16
Rversteeg Master Member Last Online: Today 16:35 Join Date: Feb 2006 Location: Amersfoort (NL)	Crank sensor The ECU first needs to know in what position the crankshaft is before it will start injecting and igniting. So it is normal that it takes a while before the rev counter (which is directly connected to the ignition coil) start to move. The mark on the flywheel first has to pass the crank sensor. Sometimes it is almost immediatly, sometimes it takes almost a full crankshaft rotation before it passes the sensor.

Apr 18th, 2016, 16:53	#17
Eyebrows123 Member Last Online: Jan 15th, 2024 08:33 Join Date: Jan 2016 Location: Cambridge/Bristol	That does make sense. But then after the crank sensor picks uo its location it does another 1-2 rotations before it'll fire. The rev counter will bounce a little which would kind of imply the crank sensor is working I would have thought? I'll have a wiggle of it next time it's running but what could be the cause of the delay of it starting? Could it be the crank sensor not being accurate or something else? Last edited by Eyebrows123; Apr 18th, 2016 at 16:56.

Apr 18th, 2016, 18:31	#18
Dirty Rooster Premier Member Last Online: Nov 23rd, 2023 14:26 Join Date: Jun 2014 Location: Haltwhistle	Yeah that sounds like the crank position sensor. 10mm bolt, oily arm job. Bit like a vet with a heffer. __________________ 1993 2.0 Turbo SE with 1991 2.0 Turbo engine. Older is better!

Apr 17th, 2016, 18:05	#11
Eyebrows123 Member Last Online: Jan 15th, 2024 08:33 Join Date: Jan 2016 Location: Cambridge/Bristol	So, I finally got to look at my car today and got to the fuel pump relay (it's the big white one right?) and could remove it but couldn't figure out how to remove the whole relay assembly so couldn't really see whether any joints needed attention or not. I had a look at the rev counter whilst cranking, it did nothing for the first 1 second of cranking then it bounced for the 2nd second of cranking then the engine started. It does seem to take a fair few cranks to start the engine though, I don't know if that is normal or not? I'll try get a video next time I'm able to get to the car if possible. The vacuum lines all looked fine, I didn't check the T-piece with the engine running but it looked ok. I also removed the intake pipe from the throttle body and had a look inside and it did look remarkably clean, it wasn't spotless but was pretty good, no carbon build up on the intercooler side of the butterfly valve. Didn't get to see past that though, should I have checked that? Hope you guys can help, sorry for the slow reply. Cheers

Apr 17th, 2016, 20:04	#13
Eyebrows123 Member Last Online: Jan 15th, 2024 08:33 Join Date: Jan 2016 Location: Cambridge/Bristol	Seen it, how do I test it or do I just have to buy a new one and swap it

Apr 17th, 2016, 21:02	#15
Eyebrows123 Member Last Online: Jan 15th, 2024 08:33 Join Date: Jan 2016 Location: Cambridge/Bristol	Ok, thanks, will have a crack at that later then Thanks for the help, much appreciated

Apr 18th, 2016, 18:33	#19
Eyebrows123 Member Last Online: Jan 15th, 2024 08:33 Join Date: Jan 2016 Location: Cambridge/Bristol	Ok, might buy a replacement anyway that way at least I know it's done. Where's the best place to get one, FRF?

Apr 18th, 2016, 18:41	#20
monkeh Pain in the backside Last Online: Today 10:10 Join Date: Mar 2007 Location: Newport	Ebay... £25 tops __________________ 'Designed by a computer, built by a robot, and driven by a f***ing nutter' '09 XC70 SE - 2" lift, D5 225bhp, poverty spec.

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