My 93 240 wagon will occasionally crank and not start if the engine is hot (turned off in the last 5 to 30 minutes) and the outside air temp is about 80 or above. It can take anywhere from 10 to 60 minutes of sitting before the engine will fire up again. This has only happened to my kids when they are running around town from location to location and I'm not around. I've not been able to reproduce it or pinpoint the issue(s), so I'm looking for suggestions.

All of the following were replaced about 6k miles ago:
- Coil - Bosch
- Plugs - Volvo OEM
- Wires - Bougicord
- Cap/Roter - not sure, but cleaned it
- Fuel pressure regulator - not sure, done before I got the car - no leaks
- Fuel filter - Bosch

I've read this could be crank position sensor issue, but I don't know how to diagnose it. Any ideas?

I don't know the fuel level when this has occurred - could that be an issue?

What else should I be testing?

Thanks!

Clean and retention fuses 4 and 6.

When the engine won't start hold the fuel system relay and see if it clicks two times while trying to start.

If not resolder the circuit board or replace the relay.

Look at wire lead for the crank sensor for cracked or missing insulation.

Dan

Fuel pump relay was replace about 2 months ago - Volvo OEM - which fixed the problem of the car dying while driving down the road. Those were fun times.

No cracked insulation on the CPS. I've reseated the connection a few times. I've not been able to inspect the CPS itself as that seems very tricky to remove. I've seen the 7/9 series methods posted, but it looks like a much tighter fit on the 240. Any good methods are much appreciated.

Fuse holders was sanded clean and new fuses installed about 12 months ago. That fixed a number of issues. 4 & 6 have good continuity across the holders.

Thanks.

Sometimes the power stage / ignition amplifier fails when it gets hot and works fine when it cools down. You could try a new coat of thermal paste on the back of this and see if that helps.

CPS is a bit of a pain and about the only thing that really helps is small hands! I straddle the engine with a flash light in my mouth and either use a ratchet and socket with extension(s) or a closed end wratcheting wrench. Getting it off is easier than starting the bolt when installing it.

If your CPS insulation is not cracked or missing near the sensor I would leave it alone for now.

Dan