Volvo: Engine shutting off, volvo specialist, fuel pump relay

Question
I have a 1994 Volvo 850 4-door sedan with 161,000 miles. Recently it starting shutting off under various conditions. I could be on the highway going 65 mph and it would simply shut off (like the engine ran out of gas)or I could be at a light idling and it does the same and everything in between. After a few minutes, it starts right up and off I go. It can go 2 weeks with nothing or shut off 5 times in one day. My mechanics are baffled and have tried various things, most recently they installed a new fuel pump and it was great for 2 days and then it happened again. Prior to the installation, my mechanic drove it for a while with guages on it so he could attempt to isolate the cause. When it shut off on him, the fuel guage was at only 5 lbs of pressure which made him think it was the fuel pump.

I should also tell you that during all of this the car overheated (fan was not working, supposedly the wire was not hooked up)and the block cracked so I had a used engine installed.

There doesn't appear to be any rhyme or reason to when it does happen but it always starts up again after sitting for a few minutes. It seems to me it happens more frequently in the hot weather but who knows. The only other weird thing the car has done maybe a few weeks prior to this starting to happen is that the horn came on by itself and    we had to disconnect the wires to it to make it stop.

I really hope you can help. I find it interesting that when I did a search on the internet for this problem, you had another 1994 850 volvo sedan with a similar problem. It was dated 8/12/2003

Answer
Hello Barbara! The first thing I would do is check for fault codes in the ECM. A special tool is needed that only a Volvo specialist would have. Sometimes the computer will store a fault that can guide you in the right direction. I would also check the fuel pump relay, cam position sensor and crank sensor. These items can cause the problem you are describing. If the engine was replaced, I would make sure all wiring is ok and connected to the right places. The horn problem is most likely caused by a fault in the steering wheel. You may have to replace the wheel. I hope this info helps you.

Jimmy