My 1991 Volvo 740 Sedan with 130,000 miles stalls at any given time. But usually when the engine is warmed up. A month ago I had the fuel pressure checked & it was normal. I recently thought it was the electrical system having a problem, after having that system checked, I found it had a bad cell in the battery and had it replaced. But still, driving down the road at any speed or even at a stand still it stalls out. Sometimes it will run up to 3 weeks without stalling and sometimes it will stall 5 to 6 times a day. After turning the ignition off, then back on, it will usually start right back up and go but not always. Sometime have to let it set awhile and 5 or 6 tries later will start. Last time it stalled, I checked for codes and there were none. Would appreciate any help I can get. Thanks, Pat

Resolder the fuel pump relay AND the "radio suppression" relay (under the hood). My '91 740 stalled -- it was the pump relay. A month later it stalled again -- it was the suppression relay.

I became frustrated and resoldered every relay in sight and the relays in the next car over.

So far neither car has hiccupped again, and that was two years ago.

This will cost you nothing, whereas replacing the crank sensor DOES cost something. So try the free 'n easy stuff first.


Don Foster (near Cape Cod, MA)

Hello, I would go off the first response that you recieved, it is called a crank sensor, an easy way to diagnose the crank sensor is to watch your tach when the car dies. If the tach drops you know that it is the crank sensor. Your crank sensor is designed to take and accurate reading for your distributor to fire upon crank position. It is a little sensor that looks down over the "flexplate or flywheel" when the crank sensor goes bad like any other circuit or contact it goes open circuit and looses contact and will not work anymore so the engine will shut down, after it cools off and regains contact within the sensor the car will work again like normal. If you tach does not fall when it dies, then you have a fuel related problem, fuel pressure regulator, accumalator or pump...... we can go from there, good luck!!!!

I agree with David, your first step is to resolder the fuel pump relay.

If you find that your problem generally happens with the engine warm, this is a common problem with the RPM sensor. It is fairly cheap and easy to replace. When I had this problem, the engine would just die, no sputtering, just dead. It did leave a code on the computer, but it may be possible that it could fail and not leave a code. Also, if this part has never been replaced, it would not hurt to replace it now as a preventative measure, as they seem to have a limited lifespan. Check the 700/900 faq for information on this sensor. The car that I had (girlfriend's car actually) was a 93, and the sensor failed this year.

Greg

The first step for this problem is the fuel pump relay. Resolder it, cost nothing and takes 10 minutes. It is such a common problem rhar many Volvo owners resolder as a preventive measure.

It is difficult to diagnose such an intermittent problem unless it occurs during testing. It will be important to know if the problem is fuel or ignition related. Next time you are attempting to restart without success observe if the tach nudges up slightly during the time starter is cranking.
If it nudges up- fuel related problem
If it does not - ignition problem (no spark)

I was having that problem. 6months ago i would be driving and the rpms would jump all over and car would stall. i thought it was the rpm sensor. But it wasn't. it turn out to be the conection right next to the battery on the body of the car. Where i live it rains alot and the conection was coroded. One way to test this is to grab the cable and wiggle it. if car dies you know. So i cleaned sand paper so contacts were shiny. then i put some electrical grease on the contacts to prevent problems in the future. No problems sense.