1990 740 stalling in rainy and cool day duri highway driving

C.Lam · Post by **C.Lam** » 09 Oct 2002, 21:52

I drive a 1990 Volvo 740 GLE with a 16 valve engine for sevral years without problem. Lately, it's engine check light was on. It was checked by the mechanics but could not find any problem. However, it began to stall a few times during high speed driving when the weather was cool and misty. This happened more frequently if the car was driving in that conditions initially, stopped for a few minutes and restarted for driving. It would continue for about 10 minutes without problem. After that, the engine could behave as if there was water in the fuel line. The engine running was rough and began to lose power and eventaully stalled. It is the least to say that it was an unpresnet and dangerous expereince. Strange enough, after about 30 minutes, the engine could be restarted and no more problem for driving. Eventaully, I found one mechanic who fixed the engine check problem by replacing the speed sensor. The engine performance, occasionally, was also rough but did not stall this time during the same cool and misty conditions. I would appreciate very much if this problem be explained so that I could fix it.

760ti · Post by **760ti** » 11 Oct 2002, 18:35

Have you replaced the cap & rotor lately? moisture may be getting into cracks in the cap, causing the symptoms you're describing when it's wet out. As far as the check engine light, your car should have an OBD system that will flash out codes, telling you why that light is on, including bad or missing signals from the RPM (speed?) sensor. However, those codes arent' supposed to trip the check engine light.

Tore · Post by **Tore** » 03 Nov 2002, 12:43

What stopped a 740 in Quanah, Texas, was a defective fuel injector relay. It had been running rough for some time, getting worse and worse. The relay is on the right side of the engine compartment on the front of the coolant reservoir. Fortunately, there are two relays there. The second one is for cold weather start assist, similar to a choke on a carbeurated car. It is not used much, so it can act as a spare. Just remove both connectors and switch them. It it runs better, replace the defective relay at the first opportunity.