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1990 Volvo 240 won't start if it sits in the sun

Darn thing hates summer.Starter works. Turns over OK, but won’t catch until the shade hits it. Any Ideas?

You more than likely have a bad fuel pump relay. I had the same problem a few years ago. To test it for sure, on a hot sunny day when the car will not start, pull the relay and pop it in the freezer for about an hour. Then plug it back in right from the freezer. If it starts, there ya go. They go for about $50. Good Luck!

Are you parking it in a damp area, like a lawn? Have you checked to see if you have a strong spark at the plugs?

This is an interesting one.

To make sure the problem is in the fuel pump circuit, take a loop of wire (a paper clip will do) and short between fuse #4 and fuse #6. The pump should spin up and the car should start.

If that works, the fuel pump circuit has a problem, but I doubt very much that the relay cares whether the sun is hitting the car. That relay is nestled far away from any exterior surfaces of the car, and fairly isolated from cabin temperature. It is above the thick felt panel, right above the passenger’s right foot.

The fuel control computer, however, is behind the kick panel to the right of the passenger;s right leg. It is near the exterior of the car and might be sensitive to the sun shining on the right side of the car, though I have never heard of this before. The fuel control computer provides the ground signal that closes the fuel pump relay. When it fails, it stops providing that ground signal. You could test that theory by pulling off that kick panel and putting an ice pack wrapped in a towel on the computer to cool it a bit.

I have replaced the fuel control computer in my 1990, and I have replaced the relay twice in my 1991.

Also, on the 1990, if you have not done it yet, pull out all the fuses and throw them away. Buff up the holders and put in fresh fuses. You will save yourself a lot of quirky electrical problems due to corroded fuses. Oddly, my '91 does not have that problem. Different fuse material, I guess.

Thanks to one and all for your help.I will be trying out these suggestions and will get back in touch when I have some more data.