My 1986 240 will start easily and after 5 - 10 minutes it stalls. Then will not start again until after it sits for a long time (hours). I recently had a problem with the flame arestor and it leaked oil in the engine compartment. I power washed it which blew off the insulation on the wiring harness. I replace the wiring harness. I still had this problem so I have replaced the O2 sensor the crank position sensor and removed the catalytic converter. Does anyone have an idea of what my problem could be or what I should check/replace next? The car has less than 150,000 miles. It does not look like the fuel filter has been changed in a while.

I had a similar mystery problem on my 85 240.
After months of guessing,and replacing many parts,it turned out that the problem was a faulty plug wire.
The wire had a bad spot where it plugs in to the distributor.
The car would usually start,then it would die after the engine came up to temp.Sometimes it would just not start, and then,an hour later, or the next day,it would start immediatly.

Sometimes it's the simple unexpected part that is the problem.

First check when it doesn't start:
Any spark?
Plugs wet or dry?
Narrow down between fuel delivery or ignition.
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Post Back. That's whats makes this forum work.

Yes, check spark.

Sounds perhaps like something heating up, shorting out.

Like, coil. But I wouldn't think 10 mins would be enough time for a coil to overheat...

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-Matt I ♥ my ♂