Logo
FULL SITE MENU

97 Yamaha 115 saltwater series 2 stroke develops a shudder and loss of power at high RPM

B

BillBooth

New member
I have been chasing this problem for several months and have had it to three different marine mechanics with no luck on curing the problem.
The motor runs great on a hose! I put it in the water and run it anywhere from 5-35 minutes and it develops a severe shudder and loss of power! I go into neutral and rev it several times, it clears out and restores power, put it back in gear and run for a few minutes then goes back to the power loss and shudder.
The engine never shuts off or stalls, it just looses power. It will also run all day in gear at 1700rpm but as soon as you get it up running over 3000 it looses power.
The carbs have been rebuilt by two different marine mechanics! I recently replaced all of the fuel lines, water separator, cleaned the tank and filled with non ethanol fuel... the problem is still there!
Im starting to think electrical. coils, stator?
Can someone please give me a clue on how to fix this?

Thanks, Bill
 
Testing on a hose means nothing here,--------Start with a compression test.--------Time to do some real and simple testing .----You run with a timing light and see how spark behaves when motor falters.----Test all 4 leads.------Then use a strong flashlight to look into the 4 carburetor bores to see how fuel coming up the jets compares one carburetor bore to another at full throttle.
 
faztbullet said:
When it acts up pull the plugs and inspect them for moisture especially the lower 2 cylinders.
Click to expand...


^^^^^^^^^2nd that having lost a 1996 115 SS last year doing the same thing, but mine took it a little further and would lock down and shut off. Wait for it to cool off a few minutes and it would run all day, or at least 8 miles which is how far I had to idle to get back to dock. Good Luck and apparently those motors had a corrosion issue with lower seal or something like that.
 
Back
Top