Intermittent stalling, 94 850

jjdemann · Post by **jjdemann** » 13 Nov 2007, 19:44

Hello, I have a 1994 Volvo 850 that stalls intermittently while driving without notice. Sometimes it will happen daily, other times I get lucky and the car will go several days before it stalls while driving. It sometimes stalls at a stop while idling, and sometimes it will stall during normal driving. The car always starts back up after sitting for 1 - 3 minutes. I've tried fuel cleaners, changed the fuel filter, and replaced the vacuum elbows that were worn. The check engine light is not on, and does not list any faults. Any insight into this problem would be much appreciated!

Thank you,
John

Post by **MadeInJapan** » 13 Nov 2007, 20:05

Very hard to pin point from here...if you haven't already, clean/replace your pcv system and also clean your throttle body and MAF sensor.

karageorge2 · Post by **karageorge2** » 13 Nov 2007, 21:09

Almost sounds like a coolant temp sensor but you would have a cel and code on that.

does it do this when warmed up and not when cold? warm could indicate electrical (fuel relay-fuel pump injector)

from my experience the last time i dealt with this exact thing it ended up being the fuel pump relay. hard to test this other than by replace and hope (at least that I know of). Reason being, once it warms up it will react differently which makes it difficult to test.

also check the vacuum line going to the fuel pressure regulator under the fuel rail-that little bugger tends to get eroded.

tripleb · Post by **tripleb** » 13 Nov 2007, 21:46

Sounds like something electrical, like the f/p relay, like previously posted, or the fuel pump.

These are 2 things that will not leave a DTC if they fail, unlike the temp sensor or vac hoses.

Is it a Turbo?

How did you check codes?

This may have a separate fuel and ignition computer, and you may need to check both for codes.

B

Post by **MadeInJapan** » 13 Nov 2007, 22:21

Same computer...different holes to insert in the diagnostic box to check these things, and it's always good to check for the codes even though the check engine light isn't on....that doesn't mean there aren't codes stored.

kurt robinson · Post by **kurt robinson** » 14 Nov 2007, 10:34

A bad cooling temp sensor doesnt always produce a code or CEL. In my case a couple of weeks ago never did it produce either.

jjdemann · Post by **jjdemann** » 14 Nov 2007, 13:55

Thank you everyone for your thoughtful replies. My car is not a turbo. I've checked the codes using the method from the Haynes manual (plugging in the wire on the A/B box, tapping the required code, etc.) Currently it does not register a fault code. The problem occurs when the engine is warm, but it can stall out after only a couple of miles driving. I've done quite a bit of investigating on different forums, and most recommendations include replacing the fuel pump relay. Thank you for any additional thoughts on the problem.