1986 90 hp mercury outboard

[krusty the clown]

Hope someone can help. I just purchased this boat and motor and it seems to run fine except at full speed then engine will hesitate every once in a while for only a second. Wondering if anyone else has had that problem? Also on inspection of the engine there is a bit of cracked paint on the head between the number 3 and 4 cylinders. It looks like, for lack of a better name, that there is a frost plug at this point and I was wondering if this is common around this site or am I looking at an overheating problem? Thanks any help is appreciated.

[greasemonkeyozi]

You might have small amounts of air seeping into your fuel system, but if it only happens once in a whhile, I wouldnt worry. Try replacing the connection that connects the fuel line to the motor as well as the fuel line to the tank.In time, the O rings inside of these fittings will dry rott and keep from sealing. Buy you some small screw tight matal hose clamps and add them to all of your hose ends on your motor from the fuel tank all the way to your carborators. I have noticed that on some motors, the manufacturers only use zip ties for hose clamps, why, I dont know. If this does not fix your problem, you will at least know your fuel system will be well sealed.

[greasemonkeyozi]

Oh yeah, forgot to mention, try replacing your primer bulb on your fuel line. All these parts, your fittings, hose clamps, and primer bulb can be bought at wall mart on the boating isle next to fishing. Good luck.

[krusty the clown]

Thanks, appreciate the reply. You don't have any idea about the cracked paint on the head do you?I'm new to this engine and it only seems to be in the one spot around this bolt head between the no.3 and no.4 spark plug.Thanks again.

[rodbolt]

Hello I dont think this engine had a head. but I am not looking at my manual right now either. high speed problems are hard to chase. make sure your fuel system is clean including the carbs. what is your engine seriel number. merc motors really cannot go by a year only by a seriel. good luck and keep posting