1994 850 Turbo 180,000 miles

[Mohjoh71]

I have a strange no start condition. Starts in the morning fine. I drive 4 miles to work. Come out at noon for lunch, starts fine. Drive 4 miles home. 40 minutes later, cranks but no start. Wait an hour, starts fine. I changed the fuel pump relay, injector relay, coolant temp. sensor, all one at a time with the same results. When in the no start state, I checked fuel pressure, it was fine. I let the pressure out and cranked again and fuel pressure was again present. I haven't checked for spark when in the failed state yet. There are no codes posted from the OBDII. That's where I'm at.

[northernlights]

Either the crank or cam sensor will prevent the car from starting, but it can actually run with a bad cam sensor, or at least that's what the Motronic books say. If you haven't had any weird shut offs while driving then the cam sensor might be worth looking at.

I replaced both the cam and crank sensor (and the fuel pump relay) at about 150k miles on my 94 as preventative maintenance. Prior to this the car would occasionally stumble while driving almost like it wanted to turn off, and seeing that all three of the parts I mentioned were very old, and could keep the car from starting, it seemed a good idea to replace them before they failed. The plastic connector on the cam sensor disintegrated when I unplugged it, so it probably wasn't making the best connection.

[Mohjoh71]

Thanks, I check it out. It doesn't do anything else weird when running. It has never died or stumbled, Just the no-start after sitting 30 minutes. If I shut it off and try it immediately, it always starts right back up.