1988 OMC 3.0 Litre Ignition -We are on to something

Ksch439928

Recruit
Joined
Aug 17, 2015
Messages
5
I FINALLY got back to doing more diagnostics on my OMC engine that would run GOOD for about 20 minutes to 1/2 hour then start to mis-fire & stall.
The problem lies between the alternator / regulator and the 3- wires " 1- resistor wire - connected together going to the coil. I can connect to 12 volts directly and it immediately runs properly. OK ,SO what do you think ? I will check the alternator output ,currently on the boat Amp Meter it shows 13 volts, the Alternator does charge. The regulator , not so sure if its acting properly, Well give me YOUR opinion it is always appreciated. Thank You
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
What is the voltage at the coil when it starts running poorly and when it is running properly?

What is your dwell set to? You set it with a dwell meter?
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
I think there is an inline resistor that could be breaking down.
Bruce asked for the volta​ge when it breaks down. Post that.
There are a couple of inline fuses that might affect that when they get hot.

The coil, is it getting hot?
It's supposed to get warm but not so hot you can't keep your fingers on it.
How hot?
Look under the contact/points plate and see if there is any corrosion?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
If your "ammeter" shows 13 volts you are looking at a "voltmeter". If the "voltmeter" is showing 13.5 - 14.5 volts at anything above 2000 rpm the regulator is working. Since helm-mounted instruments are notoriously inaccurate, use a quality voltmeter to check alternator output at the battery.
 
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