Merc 115 Hard Starting

Hello for the first time. First I would like to say that you have a very fine site online. Second I have a 1987 115 Merc Inline 6 that is giving me a fit. Since there are no COMPETENT outboard mechanics around here I am doing all the work myself. So far I have rebuilt the carbs and they are in perfect syncro. Timing is right on the money. When it finally does fire you couldn’t ask for a better running motor. It is a bugger to get started when cold. Compression tests and leakdown have been tested and results are all within minimums. I have found that the best way to get the motor started now is on initial startup for the day that I have to trim all the way under. After that the motor will hit on the first crank almost every time. Let it sit long enough to cool completely off and gotta crank like crazy to get it running again. Any advice would be GREATLY appreciated as I am ready to pull my hair out and plus it has almost cost me a few tournament wins trying to get cranked back up to make the run back to the weigh in. By the way, it is on a custom (by myself) 16ft Laser V-Hull.

Thank You
Dirk Courtney

Unfortunately, since you've done all the other tests I'd next look for the reeds, or more importantly, the reed boxes. The reed boxes double as the crankcase seals in this motor. When worn they will cause hard starting among other things. When you have drowned them with fuel they seal better, hence the "warm start" mode. Double check the choke operation but then dig deep and check out the reed assemblies.



Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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