1993 Volvo 850...weird coil wire-distributor issue

[bjack56]

1993 Volvo 850 GLT will sometimes start & run for a couple of minutes, then rough idle & dies. Sometimes will not start but tries to fire.

If I take the coil wire off of the distributor cap & hold the coil wire end just above the distributor connection (which makes it produce a "hotter" spark) it starts & runs great. As soon as I reconnect the coil wire to distributor cap the engine coughs & dies.

I try to use OE or OEM parts, usually FCP Euro, when replacing things but ignition coil & distributor cap are pricey. Don't want to fork out all that cash for one or both if not needed.

Any idea what is causing my problem?

Thanks

[RickHaleParker]

This sounds like a classic for us guys that grew up with electrical-mechanical cars.

Inspect the distributor cap for hairline fractures. You may need to clean the cap to make them stand out.

When the wire is in the cap the current leaks through the hairline fractures. When you pull the wire up the resistance increases enough that the leakage is insufficient.

[RickHaleParker]

I recall some guys would toss the old but still working cap and rotor in the trunk. As a precaution against getting stranded in the middle of nowhere.

[volvolugnut]

Most of the time, poor running on a distributor engine is an electrical problem in the wires, rotor or distributor cap. Sometimes a coil will go bad, but not often. If it is old enough (yours is not) to have points and condenser, it took even more regular maintenance.

volvolugnut

[bjack56]

thanks RHP & volvolugnut