Mercruiser 165 Ignition coil/distributor problem?

[auscarter12]

I have a 73 model Aristocraft with a Mercruiser 165 inline 6. Recently I have been having issues with it not starting or dying after running for a few minutes. I am sure the problem is electrical, but I need some direction. First the problem was a loose wire at the ignition switch keeping the ignition coil from getting power. I corrected that and made sure the coil was getting power, which it is (my test light shows power at both the positive and negative terminals of the coil, is this normal?) Now I am having trouble with the distributor. The ignition wires were replaced last year and show no signs of wear. The cap and rotor were also replaced last year, as was the ignition coil. Seems now that the distributor will give spark some times and not others. Once I do finally get the motor cranked, it may run anywhere from 30 seconds to 3 or 4 minutes before abruptly stopping (almost like the ignition is being grounded somewhere and cutting off circuit). Upon trying to restart the engine I come up with the same issues - no power from the distributor or coil. I don't have a lot of knowledge about electrical systems and frankly I try to avoid them if possible for this very reason - any ideas what this could be? Ignition coil or distributor?

 

[Scott06]

Points , condenser, set timing verify that shift interrupter isn't grounding out- disconnect the switch for trial.

 

[fishrdan]

^^^ Yep...

You're going to need a dwell meter and timing light to do the job properly, or a timing light with the dwell function built in. Set dwell first, then timing.

An old distributor could have bad bushings too. This will throw off dwell and timing, and cause all sorts of weird issues like you are experiencing. If dwell and timing are jumping around, this is a good indication of bad distributor bushings.

 

[auscarter12]

Does this sound like it could possibly be the shift interrupter switch acting up/being out of adjustment?

 

[Bondo]

(my test light shows power at both the positive and negative terminals of the coil, is this normal?)

Points , condenser, set timing

Ayuh,..... It's perfectly normal, til the points close,....

Start with the points,....

Yer's are corroded, 'n can't make ground,....