No spark

[poverty stricken II]

I have a 1986 mercruiser alpha one with 230hp 5.0. The issue is no spark from coil. At first it started however would not idle. It would run over 1200rpms. Replaced plugs, wires, rotor and cap as general maintenance anyways. Restarted and had same issue of not idling. Assuming it was a fuel issue I pulled the carb and cleaned it out. Restarted ibut would oNly go to 1000rpms and die like it was out of fuel. This happened 3 times and then it would not start. Pulled carb off and rebuilt it (nothing was found and no dirt. Reinstalled and still no start. I check and wasn't getting spark. Check for power to coil and that's good with 12 volts. Did the resistance check and seemed to be inside the guidelines but figured it wouldn't hurt for a new one anyways. Replaced and no spark. I think there are only 2 other options to check but don't know how to test. Ignition sensor inside distributor and the thunderbolt IV ignition module. Anyone know how to test these eor where else I should check? Ps the shifter interrupter was fine too.

Thanks in advance

[lakebound88]

I believe you can check the signal out of the module. See if the coil is receiving signal to throw spark. Should be the wire opposite of the hot wire? I am not sure without looking but maybe its blue? Not quite sure. If you need a hand, let me know maye a second set of eyes can help. Live right around the corner from ya.

Nick

[poverty stricken II]

Thanks nick, ill give u a call tomorrow

[woody 184]

Poverty your coil is bad. I had the same thing on my Penn Yan 5 years ago. It acts like its starving for fuel and its just the coil sending intermittent spark.. Replace the coil and she will purr like a kitten....

[poverty stricken II]

Woddy, thanks for the response. I had already replaced the coil however still no spark. I tested the old one prior to replacing it and resistance was within limits albeit on the high side. So I replaced that. Was able to download the ignition flow chart and it turned out to be the sensor inside distributor. Ordered that today and hoping it will be here Monday. With a new ignition and fuel system clean she better purr, lol.

[Chas0218]

I was just going to say check your ignition module. haha

 

My old camaro had the same issue with the HEI distributor.  Glad to see you got her fixed.

[poverty stricken II]

Got the new sensor in and she fired right up. Don't like the "replaced" version one the way it connects. The old one had 2 post and the wires connected direct. The new one has the wires sealed and you have to use the pig tail, screw together, and heat shrink over them. All of that was provided in the kit. My concern is if the shrink wrap wears through it would ground out the system.

Oh well will tape over them and put chafing wrap to prevent.

Thanks for the advice

PSII

[Chas0218]

Throw on some dielectric grease over top too