Here's one that is driving me crazy. Our '87 740 Turbo wagon (322,000Km)has an intermittent fuel fault. Cranks OK, sparks OK, but won't start.
We have so far been through the all the usual offenders.
First was resoldering fuel pump relay, then replaced the tank pump, then the main pump. Each time we think it's fixed, but after a few days or weeks, the same problem occurs. It has been difficult to pin down, because once it starts and behaves normally, it is not possible to find the fault.
By squirting fuel into the manifold, the engine starts, will stay running fine, can restart it hot, cold or whatever for another period of time until the problem returns. After looking at the FAQ's it appears that the Radio Suppresion Relay (which never occurred to me as a cause) may be the the next investigation on Monday, but I would like to know if anyone has any ideas in the meantime in case this does not work.
For the record, I have still not found a hill that this car will not accelerate up, even with a full load. Starting to use oil now, and need to check every week, but otherwise has only had the regular servicing and an A/C compressor replacement.