1978 Mercery 115 Tower of Power (lost spark)

Mpaul1978

Recruit
Joined
Aug 27, 2014
Messages
1
Well boredom got the best of me and I bought a little speed boat with the above motor on it. The motor was running fine until all the wires connected to the positive battery terminal fell off. The motor of course died. Not knowing any better(first boat) I reconnected the wires with the key still on and must have fried something. The boat will crank over but now has no spark. Can anyone give me details (step by step) on what to do to trace down where he problem is? Coil test? Trigger test? Switch box test? And what ever tests that should follow? I have $2500 into this boat as it sits now and don't want to throw more good money after bad on this. I bought this boat on a whim, $2000, registered it $80, had the trailer bearings redone $170, had the motor gone through and choke system fixed $150, then this happened. I can't get anyone to help me with this problem (Gray, Maine) all the dealers want me to leave it which I don't want to do. I don't mind paying someone to show me things. But I won't drop things off. Is there anyone on this forum in my area? Anyone have a link to an on line manual? Or just anyone who can give me some step by stop procedures to fix this thing. Also if anyone wants to take this off my hands $2000 and its yours. Comes with a complete parts motor. Thanks Mike
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,667
Chances are good that the voltage rectifier is fried, and possibly damaged stator.

The switch boxes and coils generally take some abuse without serious damage.

Sorry, I don't know of any free online manual.
You need to get a manual and do the diagnostics to determine which parts to buy.

But, if you have a complete parts motor, why not switch out the electrical system and go from there?

Generally speaking, you should only have 2 wires on the positive terminal, maybe 3 on some boats.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,148
That motor has a distributor and a single coil, right? I would expect the rectifier is bad. The motor does not have a voltage regulator, so good news there.

The CDIElectronics web site will have a test for your battery-powered CDI system. It will check out the coil, wiring and switchbox. If they are good, and you still do not have spark, the trigger is the suspect.

BTW - the rotor is real fragile and non-removeable. Also, likely your stator is fine, as it is only used to charge the battery. Check your wiring. By this time, most original wiring is bad on those motors.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,148
That motor has a distributor and a single coil, right? I would expect the rectifier is bad. The motor does not have a voltage regulator, so good news there.

The CDIElectronics web site will have a test for your battery-powered CDI system. It will check out the coil, wiring and switchbox. If they are good, and you still do not have spark, the trigger is the suspect.

BTW - the rotor is real fragile and non-removeable. Also, likely your stator is fine, as it is only used to charge the battery. Check your wiring. By this time, most original wiring is bad on those motors.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,618
Trigger is bad, loosing voltage or disconnecting battery while running is usually instant death to it...
 
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