miss on 70hp merc outboard

[tom222]

1988 70HP Merc Outboard. Intermittant miss. Sometimes it starts right away; other times if ride for a while and then it starts - but usually once I get all 3 cylinders running, it will be OK for the rest of the day. It seems to be an electrical not gas problem. I don't know where to start. I have heard it could be wires, coils or switch box - but before I start replacing I would like to hear best guesses. Replacing some of this could be expensive. I tried to ensure that the wires are firmly in place. Help! Any suggestions? Tom

 

[KCLOST]

Re: miss on 70hp merc outboard

This could be a few or more things.... <br /><br />Ok, If you have ear muffs let's do some testing in the driveway (I don't want you to burn up the impeller)...<br />Remove the gas line from the motor. Get a spark tester and check the spark on all cylinders... You can get one from an auto parts store for not much money... Check the spark while just cranking the motor, if you see one cylinder not getting spark correctly you know where to start. <br />After that, it could be a spark plug, wire from coil to plug, wire from switchbox to coil. I don't think it's a stator problem.... Check continuity on all the leads I mentioned. If all the wires are good, we'll go to the switchbox next, and maybe the triggers. Check all the wires to make sure there isn't anything grounding to the block. I know what you mean by expensive, as I've just purchased two switchboxes myself. <br /><br />I would strongly recommend that you purchase a manual for your motor, you can test everything properly and in the end prevent a lot of wrongful guessing and money spent.... We will still be here to help you out however.<br /><br />Let us know what you find out...