Help with 2.5 mecury

Mack in N.C.

Old Mossy Horns
My 2.5 merc has always run great. Today it cranked up great and ran wide op great then after a few minutes it sounded like every now and the it was "misssing". it would miss just a little and then be fine. ran about 3 miles and slowed to 1/4 throttle. It then cut off. I could crank it back and run on 1/4 throttle fine but then just to full throttle and it was fine except a miss hear and there ....cut back to 1/4 and it would die. weird. I know gas is good cause I run vp 4 cycle in it with boat oil though I guess there could be some water in there? or maybe spark plug?

anyne ever heard of this.???
 
pattersonj11

pattersonj11

Old Mossy Horns
Contributor
Sounds like it could be a number of things. Fuel delivery, ignition, exhaust limited. I doubt it would be air related unless its a problem with trash in the carb not allowing mixture.

Coil, plug, carb, pinhole in fuel line, so much stuff could cause those symptoms.

Interested to hear what it was.
 
nccatfisher

nccatfisher

Old Mossy Horns
Contributor
I would put it in a tank and put a spark tester on it and see if I could get it to duplicate the problem. If you could you would know right quick which way to go fuel or ignition. The way you describe I would lean toward fuel but as much as you use it and the type of fuel that seems unlikely.
 
pattersonj11

pattersonj11

Old Mossy Horns
Contributor
I had an issue with a weedeater a while back where a return line was crimped and the a vacuum was created in the tank. It would run fine, then it would quit. Burp the tank and right back in business. Did that for a couple years. I had to service it and saw the crimped line…..duh. Not an issue since.
 

Mack in N.C.

Old Mossy Horns
Looks like it may be the plug ..doesn't look good and the tip fell off when I took it out so it must be ave been loose...don't know how that could happen
 

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