1991 3.0 Merc died out of the blue - Help?!

[rgf1046]

Hi all. I have a 1991 Larson with a 3.0L merc/alpha 1. The last 2 years since I bought it it has run great. Last weekend I came off plane, pulled the throttle back to idle, and it died as if I shut off the key. Would not start again, would not even cough. My first thought was no spark, as I can see the carb jets spraying fuel. Today I put a multimeter on the coil, and it reads about 10 volts there, as well as on the wire from the coil to the distributor. Distributor cap and wires were new last year, so I didn't they would be the culprit, especially the abrubt way it died. If anyone could suggest a next step in troubleshooting I'd appreciate it. Thanks.

 

[gshldon]

Re: 1991 3.0 Merc died out of the blue - Help?!

if it were me i would make sure i was getting spark at the plug and also make sure i was getting gas to the cylinders, if all is good then i would check the shift interupt switch,

 

[rgf1046]

Re: 1991 3.0 Merc died out of the blue - Help?!

I don't have spark at the plugs. Gas looks good. Shift interrupt is good. I think th coil may be bad. I tested it with an OHM meter as the mercrusier manual shows, and on one of the tests, the reading is way off. I am ordering one today, along with new plug wires and tach, hopefully that's it.

 

[rgf1046]

Re: 1991 3.0 Merc died out of the blue - Help?!

Well, I installed a new coil, plug wires, and tach, still no spark at the plug. Any ideas on what the next step in troubleshooting might be?

 

[gshldon]

Re: 1991 3.0 Merc died out of the blue - Help?!

yeah i would install the new coil, but also make sure the shift interupt is in good working order that will cause the problem. move the shift control around and try starting the engine.

 

[rgf1046]

Re: 1991 3.0 Merc died out of the blue - Help?!

Ok, I've installed new coil, tach, plugs, wires, cap, rotor, and still no spark to plugs. It is the Delco EST system, and I have voltage going into the distributor, but it appears nothing is coming out. Any ideas on how to narrow that one down?

 

[Don S]

Re: 1991 3.0 Merc died out of the blue - Help?!

Glad to hear you are supporting parts dealers by spending a lot of money for nothing by using the "Install new parts and hope for the best" method of troubleshooting.
Have you considered

Go to the link below and look at page 4B-23 under component tests.
http://www.boatfix.com/merc/Servmanl/13/13B4R2.PDF

 

[rgf1046]

Re: 1991 3.0 Merc died out of the blue - Help?!

It wasn't until I completed all those tests a week ago that I put the new parts on, as the tests told me everything was great. Since the plugs had no spark, I figured all was not great.