No Power under load

[rickclark]

Had my boat with '86 Yamaha 150 out for the first time in over 90 days this past Holiday weekend. Started fine (always keep filed with treated gas).Warmed up for a while then revved the engine to 2500 RPM or so using the fast idle lever. Revved fine, ran smooth all through the RPM range.

Opened the throttle to bring the boat up on plane and the engine began to immediately "sputter". No power. Max RPM about 1500 but runs really rough and will not even come close to ring the boat up on plane. Shift in to neutral and the engine runs fine even at higher RPM, but once again once in gear and there is a load on the engine it really runs terrible with absolutely no power.

Any suggestion regarding diagonostics or repair sincerely appreciated.

 

[yamamarinetech40]

Re: No Power under load

90 percent chance of gum/varnish in carb(s)....todays gas sucks...only way to say it....the parts that aren't gas(profit builders for big oil, etc) cause it to degrade faster than in past....treatments don't seem to stop it or even slow it much anymore....if you've changed fuel filters as you should to start a new season, now i would disconnect fuel line at engine mounted filter(coming into filter) and put 10 to 16 ozs. of fuel into glass container with primer bulb pumping by hand....look at fuel and see if it 'zones' or seperates after few minutes and sniff....smell like fresh gas? Or crap? If it is gas, doesn't seperate, and smell right....then either the pulse pumps are worn/bad or the carbs need to be REMOVED and taken apart and rebuilt/cleaned properly....when was the last time pulse fuel pumps were replaced/rebuilt...on this old a motor should have gone thru a couple sets at LEAST by now....good luck. Oh, don't let REBUILT scare you...just requires kits to replace little stuff/gaskets in carbs....labor will be most of cost....don't pay more than 350.00 for entire carb rebuilds on this.

 

[rickclark]

Re: No Power under load

Thanks for the info from Yamamarinetech 40. I did have problem getting started at the beginning of the season because I had neglected to add fuel stabilizer at the end of last season. But based on suggestion from someone else on this forum, I drained the fuel tank and was able to prime the carbs with fresh fuel/oil mixture and it started a run fine. You may be right on regarding gum in carbs. Is there some kind of additive that might help the clean out bbefore I invest in getting the carbs rebuilt?

 

[Chesapeakegem]

Re: No Power under load

"SEAFOAM" works great on Motorcycles and lawnmowers, I use on my sailboat also...

 

[99yam40]

Re: No Power under load

"SEAFOAM" works great on Motorcycles and lawnmowers, I use on my sailboat also...

Did not know that it cleaned sails!
Thought it was just for cleaning motors

Best to clean properly before causing more problems by running cylinders lean

 

[twisterlodge]

Re: No Power under load

i had the same problem this spring. same motor. my solutoin was to remove the carbs. totaly clean them out, (blow the jets clean with compressed air.) reasemble and good to go.

 

['96 Charger]

Re: No Power under load

I had the same problem as well with my 200 ProV. 2 fuel pumps, 3 carb kits, and a whole lot of heartache from a sloppy marine mechanic later I'm running like new.

Since I have ZERO sympathy for sloppy mechanics this was at "edited because the owner of the place is good as gold". The owner of the place went back in himself and made it right even though his "mechanic" went back in himself at first and failed to catch his mistakes. Even lied about setting the air screws right. I gave the owner of the place the chewing to beat all chewings (you don't want to make me mad) and two days later I picked my boat up from something that should have been right the FIRST time, NOT THE SECOND OR THIRD.