Intermittant Stalling

[Tom]

Greetings - My car (94 850 wagon N/A, automatic) has begun stalling intermittantly. About every other day, it quits while driving. It starts back up again after one or two attempts and then continues to run fine. All of the trouble codes are clear. I hope to clear this up by replacing just what needs to be replaced. Has anyone seen this behavior and how to fix it? Any wisdom would be greatly appreciated.

Tom

[Oreo931]

MAF sensor?

have you done any recent maintenence to it? Any other specific observations about how it happens? (have you ever watched the RPM's, etc)? any other problems you are noticing?

[Tom]

MAF sensor?

have you done any recent maintenence to it? Any other specific observations about how it happens? (have you ever watched the RPM's, etc)? any other problems you are noticing?

Thanks for your reply - Yes, I cleaned the throttle body last week. The MAF sensor was replaced a year ago (Genuine Volvo part). The tune up situation is up to date although not all that recent. I don't notice any other problems - the RPM's just drop when it stalls, and the rest of the dash lights come on after the engine has stopped completely.

[echristodo]

Thanks for your reply - Yes, I cleaned the throttle body last week. The MAF sensor was replaced a year ago (Genuine Volvo part). The tune up situation is up to date although not all that recent. I don't notice any other problems - the RPM's just drop when it stalls, and the rest of the dash lights come on after the engine has stopped completely.

All the dashlights coming on is indicative of a faulty alternator. Check the charge rate.

[erikv11]

I know they are supposed to throw codes but sounds like a sensor. Cam position sensor or TPS can give that behavior. I know from experience the TPS can be bad without throwing a code. But this is a bit of guesswork, the only way to test these two things is by swapping them, understandably not what you are after. Unless you have another working 850 to borrow parts from ...

[Tom]

I know they are supposed to throw codes but sounds like a sensor. Cam position sensor or TPS can give that behavior. I know from experience the TPS can be bad without throwing a code. But this is a bit of guesswork, the only way to test these two things is by swapping them, understandably not what you are after. Unless you have another working 850 to borrow parts from ...

Thanks Erikv - I've picked up a used cam sensor and RPM sensor. If necessary I'll probably get a new TPS as they aren't that expensive. But the car has not acted up in the last two days, so it isn't that smart to be changing things now because I won't be able to tell whether it makes any difference. Maybe it was just bad gas and it's cleaning itself out? It'll be good to get some sort of closure on this one way or the other.

Tom

[David O'Brien]

I had the same problem with my 95 850 GLT, (5spd, 330 000km) in the last months.. It dies while driving, RPM goes down and lights go up in the dash.. occurred in June and last week, twice on the hottest and most humid days around here. After the first episode in June, I changed the fuel pump (it was never changed yet, so I presumed It was going bad), didn't do it again, except for last week. I've double checked everything, sensors..., no codes at all.. I'm also lost in that..

The problem is, after 5-10 seconds, the car just restarts fine and doesn't do it for a long time.. Maybe a faulty relay, dunno..

I cleaned my battery poles, maybe that will help...

Cheers,

David

[icelandic]

I had the same problem with my 95 850 GLT, (5spd, 330 000km) in the last months.. It dies while driving, RPM goes down and lights go up in the dash.. occurred in June and last week, twice on the hottest and most humid days around here. After the first episode in June, I changed the fuel pump (it was never changed yet, so I presumed It was going bad), didn't do it again, except for last week. I've double checked everything, sensors..., no codes at all.. I'm also lost in that..

The problem is, after 5-10 seconds, the car just restarts fine and doesn't do it for a long time.. Maybe a faulty relay, dunno..

I cleaned my battery poles, maybe that will help...

Cheers,

David

I had the same issue with my 94 NA at 170k miles. It turned out to be the fuel pump relay. This relay is located under the fuse box cover and is marked 103 on top. The volvo part# is 9434013.

I have learned that over time a tinny crack develops in a weld somewhere in its inards and as the car is moving sometimes the contact is lost in that crack and the fuel pump stops momentarily. It does not throw codes. Most of the times the problem occurs during deceleration, sharp turns or sharp acceleration.

This relay is not very expensive.

good luck

icelandic

[Tom]

I had the same issue with my 94 NA at 170k miles. It turned out to be the fuel pump relay. This relay is located under the fuse box cover and is marked 103 on top. The volvo part# is 9434013.

I have learned that over time a tinny crack develops in a weld somewhere in its inards and as the car is moving sometimes the contact is lost in that crack and the fuel pump stops momentarily. It does not throw codes. Most of the times the problem occurs during deceleration, sharp turns or sharp acceleration.

This relay is not very expensive.

good luck

icelandic

Thanks to all for the candidate culprits. I bought a bunch of different used sensors as spares but chose not to replace anything unless the problem got bad enough to identify one with certainty.

And instead the problem has just gone away. I think it was bad gas - 2 or 3 tankfuls seems to have flushed out whatever was combustibly challenged in there. So the computer was likely speaking the truth in offering no error codes. It was tempting for me to go changing parts on the basis of guesses, and then when one part coincided with the problem resolving itself then I could fool myself into thinking that I had the culprit. No culprits this time. Such is life with an old car I guess.

[skatehouse]

Thanks to all for the candidate culprits. I bought a bunch of different used sensors as spares but chose not to replace anything unless the problem got bad enough to identify one with certainty.

And instead the problem has just gone away. I think it was bad gas - 2 or 3 tankfuls seems to have flushed out whatever was combustibly challenged in there. So the computer was likely speaking the truth in offering no error codes. It was tempting for me to go changing parts on the basis of guesses, and then when one part coincided with the problem resolving itself then I could fool myself into thinking that I had the culprit. No culprits this time. Such is life with an old car I guess.

I hope that's all it is for you, BUT, I'm going thru the same scenario right now. Seems fine then, WHAM! shuts off, wait a few minutes, then it's fine again. Frustrating! I pulled out my TPS and tested it, seems like it's not operating correctly by the info in the Haynes manual. There's no click and the resistances are not even close to what is deemed "normal". I'll post if this replacement solves my problem. I'm also replacing the fuel relay for good measure too! Sometimes this car drives me crazy!

[Jombi]

I have a similar stalling problem on my '93 850 with 146k miles. It seems to stall about 2 minutes after a hot restart (like after getting gas). It doesn't matter if car is idling or at 60mph on highway, it just dies and all dash lights come on when car comes to rest. After a minute or so, engine starts fine and runs fine. I was getting rpm sensor and cam sensor faults. I've replaced both of these items but problem continues. I'm sort of getting used to the problem, but it is a pita. ANy ideas out there??

Dave

[Ozark Lee]

I have a similar stalling problem on my '93 850 with 146k miles. It seems to stall about 2 minutes after a hot restart (like after getting gas). It doesn't matter if car is idling or at 60mph on highway, it just dies and all dash lights come on when car comes to rest. After a minute or so, engine starts fine and runs fine. I was getting rpm sensor and cam sensor faults. I've replaced both of these items but problem continues. I'm sort of getting used to the problem, but it is a pita. ANy ideas out there??

Dave

Dave,

Since your problems seem intermittent check the proximity between your Crank and Cam position sensor wires to the coil wire. If they are close it can cause problems. Use a tye wrap to secure them away from the coil wire. Next step is to check battery connections, all of them including the grounds. Then the battery connections themselves for any signs of corrosion.

Last thing, if nothing else works/fails, change the electrical portion of your ignition switch.

...Lee

[Jombi]

Dave,

Since your problems seem intermittent check the proximity between your Crank and Cam position sensor wires to the coil wire. If they are close it can cause problems. Use a tye wrap to secure them away from the coil wire. Next step is to check battery connections, all of them including the grounds. Then the battery connections themselves for any signs of corrosion.

Last thing, if nothing else works/fails, change the electrical portion of your ignition switch.

...Lee

Lee,

How would I go about replacing electrical portion of ignition switch?

Also, I'm considering replacing fuel pump as preventative medicine; what's your thoughts on replacing only insert vs entire fuel pump assembly?

Thanks for your help.

Dave

[Ozark Lee]

Lee,

How would I go about replacing electrical portion of ignition switch?

Also, I'm considering replacing fuel pump as preventative medicine; what's your thoughts on replacing only insert vs entire fuel pump assembly?

Thanks for your help.

Dave

Piece of cake to replace the switch as long as you have torx bits. Remove the housing/collar around the middle of the steering column - As I recall it takes 4 Torx screws to get to it.

The ones nearest the steering wheel are small.

I think it is just two torx screws to R&R the switch on the drivers side of the column - it is way obvious once you are there.

As far as the fuel pump itself - A Walbro replacement will usually work fine so long as the check valve in the fuel pump assembly/frame is OK.

It is noisier.

...Lee

[Jombi]

Dave,

Since your problems seem intermittent check the proximity between your Crank and Cam position sensor wires to the coil wire. If they are close it can cause problems. Use a tye wrap to secure them away from the coil wire. Next step is to check battery connections, all of them including the grounds. Then the battery connections themselves for any signs of corrosion.

Last thing, if nothing else works/fails, change the electrical portion of your ignition switch.

...Lee

Ozark Lee,

Thanks for the advice! It's been 1 week since I changed the ignition switch and so far no stalling.

Dave