Engine 850: B5204S/2.0/20v: 850 Engine Cutting Out

[V0lvo]

Hope someone can help, as my local Volvo dealerships cannot but have charged a lot of money in trying to. I have a 1994 850 GLT with the 143BHP 2.0 20V engine. Its done a 135000 miles, with 1 owner, and has a full service history. This car has been taken care of, and is perfect, except for one detail that has developed in the last 12 months. When the engine is warm, whilst driving/coasting/braking, the engine will cut out. It happens nearly every day but is not consistent. But the engine then starts after a 2 minute pause. I wish it wouldnt as then I could get a dealer to diagnose the issue. But it does start and drives well until it cuts out again. I have had the dealer run through the cars diagnostics, and they only thing they found was the crankshaft sensor which has been replaced. But the issue was not resolved. Anyone faced the same problem and had it resolved. Let me know.

[Chris_Rogers]

Fuel Pump relay?

[warthog]

Hi,

possibly one of the commonest causes for this sort of behaviour is the fuel pump relay (103 under Fuse box cover). This can give a variety of symptoms, most not logging any fault code, but it is a simple and cheap item to try first. Also have a look at the throttle body, after a fair few miles without cleaning it can get a build-up of oil residue and cause poor idling.

Next on the list would possibly be the cam position sensor, but this should log fault codes if it fails. Then we get into areas such as engine temp sensor (faulty readings from this will give incorrect fuelling and engine cut), bad earth on coil pack (another known area of running problems), Tired Idle Control Valve, plugs, leads, rotor arm, dizzy cap.

As the car starts again after cooling slightly, it would seem to indicate a heat soak related problem, so I would look at 1. Fuel relay 2. Engine temp sensor 3. Cam sensor.

Hope this gives you something to go on.

[warthog]

Beat me to it Chris!!

[Chris_Rogers]

Originally Posted by warthog

Beat me to it Chris!!

Yes, but your answer was much more detailed and helpful!

[ShadeTek]

Let us not forget stuartvolvos epic log with his similar symptoms of not starting when hot. It looks like he had an intermittent connection at his immobiliser. I miss his log. The forum will not be the same again when it goes.

[V0lvo]

Chaps - Thanks for the prompt replies and details; will definitely get these 3-4items checked and will let you know how I get on.

[volvogirl2]

I had similar problem with my 2.5 10v 850 estate (1994). Original fault code gave temp sensor which I changed. Thought this had sorted it until couple of days later it conked out again but this time with no fault code. Thanks to your forum have replaced the fuel relay and have now had a week or so of reliable driving - great - thanks you saved me a fortune - intermittant faults run up big garage bills! Whilst I'm here what's the life span of the clutch? Have done 140000 on orginal with no problems.

Originally Posted by warthog

Hi,

possibly one of the commonest causes for this sort of behaviour is the fuel pump relay (103 under Fuse box cover). This can give a variety of symptoms, most not logging any fault code, but it is a simple and cheap item to try first. Also have a look at the throttle body, after a fair few miles without cleaning it can get a build-up of oil residue and cause poor idling.

Next on the list would possibly be the cam position sensor, but this should log fault codes if it fails. Then we get into areas such as engine temp sensor (faulty readings from this will give incorrect fuelling and engine cut), bad earth on coil pack (another known area of running problems), Tired Idle Control Valve, plugs, leads, rotor arm, dizzy cap.

As the car starts again after cooling slightly, it would seem to indicate a heat soak related problem, so I would look at 1. Fuel relay 2. Engine temp sensor 3. Cam sensor.

Hope this gives you something to go on.

[RobertE]

Hi - I've just joined this happy band and saw your problem. I had a similar issue on my old 20valve and I recall it was something to do with an oil leak from the area of the inlet cam seal wich fouled a sensor or the electrics in some way. It was years ago now and the car is long gone, but it happened at c. 100K. It was vvv expensive to diagnose, but cost about a fiver to fix.
Hope this helps. The problem has not re-presented on my AWD estate, although it has covered a similar mileage.

[Rick Barton]

Hello Robert,

Do you have an automatic Volvo? Would you keep chickens in it?

Richard.