18 HP Tohatsu

[savage]

Removed motor from storage and did the following preventative maintenance:
Replaced water pump impeller
Changed gear lube
Cleaned Carb
Changed spark plugs
Took the boat out on the water and ran the engine for 1/2 hour at full throttle.

Motor performed excellent.
Shut the motor off for 2 hrs, fished, and then restarted.....boat would not go on plane, motor running on one cylinder. Limped home.

Performed preliminary motor test in garage. Top spark plug washed clean (white) lower plug good (paper bag brown color). Performed spark plug test. Grounded each plug individually and checked for spark. Has good spark on both cylinders. Compression is #120 on both cylinders.

Started motor on the muffs and removed each plug wire while running (one at a time).
Engine speed dropped equally for both cylinders. Motor has one coil for both cylinders.

What do you think my problem is? Is it the CDI box? Trigger? Coil? or ???

 

[TOHATSU GURU]

Re: 18 HP Tohatsu

Or...None of the above. If you have spark, its not ignition. Look at your fuel system real hard.

 

[savage]

Re: 18 HP Tohatsu

I found cracked insulation (exposed copper)on two wires on what I call the "trigger". The wiring harness moves back and forth with the throttle as the timing is increased and decreased thus weaking the wires. I repaired the insulation and tested the motor on the boat for three hours with no problems. Time will tell for sure if the problem is fixed permanently.