MCM 140, Alpha MR, 1984 - unable to locate source of misfire

[boozer1966]

Very frustrating. After about an hour of running great, boat develops a misfire, made worse by turning on any electrical source (e.g. blower) and especially by activating trim. I have examined and cleaned wiring including cannon plug and related connections. The miss goes away momentarily but always returns. Anybody heard of a faulty solenoid interfering with ignition current. Anything???

 

[Bondo]

Re: MCM 140, Alpha MR, 1984 - unable to locate source of misfire

Ayuh,.... Sounds like a Bad Ground somewhere,... Start at the battery, 'n work backwards,...

Clean the connections to shiny metal clean, reattach, tighten, 'n Grease 'em to keep 'em that way,....

 

[Bob_VT]

Re: MCM 140, Alpha MR, 1984 - unable to locate source of misfire

Another old source of trouble is the ignition coil. Many coils (old coils) can develop a crack and it will only become troublesome when the motor warms up. Check your wires too.

As Bondo mentioned check all connections too.

 

[thumpar]

Re: MCM 140, Alpha MR, 1984 - unable to locate source of misfire

Measure the voltage at the coil when it is having the issue.

 

[boozer1966]

Re: MCM 140, Alpha MR, 1984 - unable to locate source of misfire

I replaced the coil this summer when the problem started. Have checked and cleaned just about every connection I can find. I agree it acts like a bad ground. I'll keep looking.