78 Merc 1150 No spark

[Davem1754]

I have had an intermittant no spark issue for the past year.
Sometimes I have spark and the motor runs good, and other times not just from sitting.
I have replaced the ignition module, coil and have repaired many corroded wires.
I suspect the problem could be in my distributor, but Im not sure how to test it?
Any info would be appeciated.
Thanks,
Dave

 

[Maxz695]

Re: 78 Merc 1150 No spark

check for hairline cracks in the cap also check cap terminals for corrosion and make sure any wires in there are conected securely. Don,t know if you have points if so check the gap and condition of the points.Possible bad condenser if you have one in there. not firmiliar with your engine but some of this info may help you somewhat

 

[daveswaves]

Re: 78 Merc 1150 No spark

It sounds like your trigger module which is enacapsulated in the distributor base. The three wires that go into the distributor run to it. It is not repairable. Must be replaced. The problem can only be troubleshot when it is not working. Go to the CDI electronics website, click on support and print off the test procedure for your set up. There are only 3 components in your ignition system, the trigger, the switchbox and the coil. It will be a process of elimination, although it sounds like you have already eliminated one, the switch box. Coils seldom go intermittent.............

 

[Gomer50]

Re: 78 Merc 1150 No spark

In my expierence with these Distributors and I have three of these,either the trigger works or it doesnt,however I had one that would deliver spark when it felt like it but only for a short time (time for a new one).I dont know what condition the three wires that come off of your distributor but they need to be in good shape and insulated to prevent shorting out. Check out your mercury switch which should be located right next to where the distributor wires connect to the switchbox undo it and see if this helps.

 

[daveswaves]

Re: 78 Merc 1150 No spark

In my expierence with these Distributors and I have three of these,either the trigger works or it doesnt,however I had one that would deliver spark when it felt like it but only for a short time (time for a new one).I dont know what condition the three wires that come off of your distributor but they need to be in good shape and insulated to prevent shorting out. Check out your mercury switch which should be located right next to where the distributor wires connect to the switchbox undo it and see if this helps.

"however I had one that would deliver spark when it felt like it but only for a short time (time for a new one). "
I have seen a few like this, thats why I suggested he troubleshoot when it is not working. It is likely the trigger, but they are expensive and if it is not the problem why change it. Bad grounds can also cause the same symptom.