Stumped

[Caddiss]

Hello. All
I am having issues with my Honda 10hp outboard motor. Its about a late 70s model, heres the problem about 6 months ago I ran ethynol gas through it and thats when all the problems started. It backfires through the carb and it wont run at full RPM when wide open every now and then it will kick up to full RPM and stay there until I slow down, then the problem repeats itself... I have cleaned the carberator out I havent replaced any components, replaced thermastat, sparkplugs, changed the oil, got a new gas tank, ran fuel treatment through the gas, checked the the compression (90psi) both cylinders....I currently run non ethynol gas
Does anyone have any ides what could be the problem??? :confused

 

[hondon]

Re: Stumped

90 PSI compression could be a little dismal for that engine.It might be time for a leakdown test to see where the the rest of that compression is going.

 

[Caddiss]

Re: Stumped

hondon,
Id to thank you up front for the reply...
when I performed the compression check I pulled the rope three times to get the 90psi reading, of course that as high as the compression was going to go anyway. I guess what I am getting at is you mentioned a leak down test what exactly would that have to do with the engine backfiring out the carb and the motor unable to run its max RPM's at full throttle? Does the compression dictate all of these sympthoms and how do you a leak down test on a motor as small as the one I have?

 

[robert graham]

Re: Stumped

Did you remove and clean all jets when you did the carb? Backfire sounds like a lean condition caused by plugged up carb. Maybe clean carb again. Good Luck!