Volvo 960 Engine Stalling

My 1991 Volvo 960 station wagon’s engine has been dying off and on for the last several months. The first several instances occurred while the car was idling at a stop light, and all the warning lights would come on. My friendly neighborhood mechanic said it could be the throttle mechanism which he cleaned, and the problem seemed solved for several days. Now it has been cutting out when I am driving (on two lane roads, usually no more than 40 mph) and seemingly when I am off the gas in a slightly slowing mode. The warning lights do not come on… I quickly shift to neutral, turn off the car, sometimes come to a stop and then turn the key and the engine turns back on. Other times I can turn the engine back on while the car is still rolling. It rained hard yesterday and for the first time the car engine quit four times within three miles, and twice on hard right hand turns, uphill. I have noticed before that the right hand turns seem to have a more than average participation in this event. So far I have been lucky - every time this has happened the car starts again immediately after this failure but obviously this is a potentially dangerous situation.

Needless to say I am taking the car back in tomorrow after having it serviced for this problem today. The spark plugs were replaced today. The engine failed twice on my way home tonight from being serviced.

Anybody have any idea what might be causing this failure?

You could have more than 1 issues here. The stall on hard right turns means the fuel pump, fuel filter, fuel pickup all should be checked as any or all could cause this symptom.

The stall as you let off the gas could be another issue, I’d check the mass airflow sensor first. If this wasn’t cleaned before by the mechanic the wire in there may need cleaning now, or replacement.

Of course all the above assumes the car was tuned up recently. Volvo’s need new plugs every 30K miles. Also new wires, distributor cap, and rotor are needed if they are a few years old or have 50K miles on them since last replaced. Volvo’s need factory Volvo ignition parts to perform well. Typical after market wires (Pep Boys, Auto Zone) just don’t hold up well in Volvos.

Thank you very much for your detailed response. The spark plugs were replaced yesterday as well as a coolant leak repaired (engine has been hot after 9 mile commute drive home, uphill, recently). The Volvo stalled five times on the way to work this morning, mostly on the flat after a one mile downhill portion - as the road turned flat the first stall happened, then it happened again in several minutes, twice in a short time, then again a mile later. I drove immediately to the shop which had done the previous day’s check, and two of the mechanics drove the car during the morning. One of the mechanics did everything he could to replicate the stalling, including hard right turns, and neither one experienced the engine dying.

Their immediate suggestion is that I let the car warm up for five minutes before starting in the morning, as my first driving is uphill for three blocks before starting down a relatively steep one mile drop to the flat portion of my commute. I do not normally “warm up” the car as I was under the impression that this is not necessary for relatively “modern” cars. The mechanics said that the car is getting old (146,000 miles) and that it in fact needs time like people getting older to warm up… rather folksy of them. However, my last Volvo (1986 740 GLE) never needed that and it lived to 450,000 miles.

They also asked what kind of fuel I use - which is normally Chevron, used to always use Supreme but now go for the middle range fuel. I did notice several times after refilling a nearly empty tank that the car had maybe two instances of seeming to “cough” or stutter, so I never let the tank get much below a quarter full. My feeling is that I should drive with the tank above half full and probably switch back to Supreme (or whatever the high octane gas is).

Tonight I drove the car home after warming it up for five minutes and had no stalling. I do not know of course whether the mechanics tweaked something today while they were attempting to find something or the warm up and fill up were the answer. After stalling five times today on the way to work I am anxious to see how it performs tomorrow with this new scenario.

I will keep your comments at hand for the next time I talk with the mechanics, which will be to either tell them their suggestions have solved the problem or that they should work through the suggestions you provided. According to the mechanics they could find nothing through the computer or their physical checks. They didn’t charge me anything for their recheck and test drive times today - good guys.

Thanks again.