Tohatsu 18 HP Misbehaving

[Sea Rider]

A low hour 2 stroke 18 HP is misbehaving strangely. Idiotic boater smashed engine's back cowl onto something, broke the upper spark plug connector, sealed with epoxy cement. When at idle one of the cylinders misfires, something like brr, brr, brr, pum, pum, brr, brrr, pum, pum through prop exhaust. Seems to be a related electrical issue, probably a ignition coil near kaput and not a CD failure. Will wrap broken connector with several rounds of electrical tape and check if issue has gone.

All fuel related, tank to carb are immaculate clean including fresh fuel, new spak plugs. Before starting swap procedure, the fastes way to troubleshoot if counting with such parts. Has someone experimented same at some time ?

Happy Boating

 

[Sea Rider]

Re: Tohatsu 18 HP Misbehaving

Update,

Cleaned and sanded both ignition coil and CD grounds, the engine idles fine for long time periods, but when giving juice starts missing and kinda not responds revving rpm up as it should. Will swap a ignition coil from other engine and check, hope it's not a bad CD, fingers crossed.

Happy Boating

 

[Sea Rider]

Re: Tohatsu 18 HP Misbehaving

Bingo, ignition coil was the culprit. Lower cap was found to be a motorcycle one including a added less wide cable as per original to match cap diam.

Installed a new IC and voila, $ 100 after and now engine purrs as a kitten. Swapping new parts is the fastest way to electrical troubleshoot issues if you happen to have them at hand. For owner luck the CD was ok, had a $ 200 saving on his stupidity



Happy Boating

 

[Sea Rider]

2 strokes 18 HP old and new ignition coils have been shutting engine down with no apparent reason, the pick up wire that connects to CD is breaking internally due to excesive engine vibration when steering friction load is too loose. Ttie & wrap cable to lower spacer tube that holds lower ignition coil to powerhead.

When changing a new ignition coil for an old model, be aware that bolts that secures ignition coil to powerhead are too long and will not achieve proper grounding once completely screwed in. Fill gap with same size washers. Adjust steering friction nut enough as to manintain same water course when tiller is hand released to avoid excessive engine vibration when working.





Happy Boating