Motor Issues, New Post

Carl

Carl

Well-known member
Staff member
Hooked up the hose and cranked up my 25 Merc. Pulled off the top plug wire, kept running.
Shut her down & repeated with lower plug wire off, cranked up and kept running. Both cylindars getting spark. Run fine at hi rpm with no load.
Took the carb off, removed the bowl and sprayed everthing down good with carb cleaner.
Stuck it all back together, took a while to get it cranked but she did and ran well with no load.
Have to get her in the water and see if I blew the carbs clean, how she runs under load.
 
I have no experience running Mercury/Mariner outboards, but have run OMC, Honda, Yamaha, Suzuki and a few of the old brands like Sears. From 1.5 - 250 HP. When you have reason to suspect any fouling in the fuel system dump some Seafoam in the tank. I like two oz per gallon or a touch more, in every other tank of fuel (because it's spendy or I'd use it in every tank). I firmly believe it cleans out the gunk, while others say it's snake oil. Pretty sure very few think it can do damage. Worth a try IMO.

Sounds like you may already have your problem solved, just a thought.
 
I think i added a whole bottle of seafoam to the 3 gallons in the tank now!
 
Carl said:
I think i added a whole bottle of seafoam to the 3 gallons in the tank now!
Click to expand...

If you added Seafoam, run the motor so the treated fuel circulates into the motor and can sit in the carb overnight, or longer. That works best for me. I think I recall others on here saying the same.
 
I ran it quite a bit a couple of weeks back, didn't seem to help. Still couldnt get above fast idle under load.
Hopefully this good dose of carb cleaner cleared up the issue. Otherwise I'll start looking at a complete rebuild of the carb & fuel pump.
 
Have you checked your fuel lines? the rubber line from the tank to the engine.
Few years back I had hi speed fuel supply issue with a70hp yamaha turned out in the manufacture of some fuel lines (mine was a Moeller if I remember)
they have a thin plastic like membrane in them that over time fuel especially ethanol fuel causes it to delaminate and restrict fuel flow especially when full fuel flow is required
Im sure if you "google it" -marine fuel line issues- you'll see what I mean.
 
Don A, I had the exact same problem with the exact same fuel line on my 140 Suzuki about 10 years ago, not that the engine size matters. They did replace the line, it was a different design and I never had trouble again. The interesting thing is that my engine wasn't conking out, just wasn't getting enough power. It was not apparent at the end of the line, I had to cut a piece to find it. Then I had a hard time believing what I was seeing.
 
Yep, replaced the entire line and bulb from tank to engine. Didn't fix the problem.
 
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