Engine Bogs down at High RPM

[ssuajk]

My Force 125 (1987) seems to run great at about 3600 rpm but then if I go higher it starts to sputter most of the time it is on a bump or wave. I feel the motor starving for fuel and surging, again mostly on waves(bounce). The compression is good, new inline fuel filter, decarbed(seafoam), stabil in gas during winter. I did have 1/4 tank of 2 yr old gas then added 3/4 tank of fresh gas to 40 gal. tank. I was wonder if gas was bad wouldn't it do it all the time, why at above 3600rpm?

 

[roscoe]

Re: Engine Bogs down at High RPM

Have heard this story before, likely is fuel system related.<br /><br />Does the fuel bulb pump up firm?<br /><br />Does it stay "full", or does it collapse after running the engine a while?<br /><br />When was the last time the fuel pump diaphram was replaced?<br /><br />Have you inspected the fuel lines from the fuel pump to the carbs, for cracks or leaks that could be sucking in air when engine is run at higher rpm?<br /><br />Have the carbs been rebuilt?<br />Possible that the floats are set too low or the valve is not fully opening to allow gas into the carb.<br /><br />Also check the fuel pickup tube in the gas tank for dirt or obstruction.<br /><br />Let us know what you find.

 

[ssuajk]

Re: Engine Bogs down at High RPM

No bulb to ck<br />40 Gallon internal tank, to fuel filter to fuel pump.<br />Pretty hard to get to the fuel pickup<br />Fuel diaphram was done 2 1/2 yrs ago<br />Carbs have not been rebuilt as long as I have had it, 3 yrs.<br />Ran fine last year<br />Will check fuel lines

 

[roscoe]

Re: Engine Bogs down at High RPM

No bulb?<br />How do you get fuel up the the motor if its been sitting for long periods of time?

 

[ssuajk]

Re: Engine Bogs down at High RPM

Shows how good I know my boat...LOL<br />I found the bulb under deck, pressurized it and saw fuel leak from fuel line between carbs 1 and 2(short piece of 5/16 rubber fuel line. I guess that would be the culpret?

 

[roscoe]

Re: Engine Bogs down at High RPM

Yes it could very well be.<br /><br />Seem hard to believe, but... when you hit a large wake, that little hose can flex just enough so that the fuel leaks out thru the cracked hose. Causes the carb to starve of fuel.<br /><br />PLEASE let us know how she runs after you replace that hose.<br /><br />Happy boating.

 

[ssuajk]

Re: Engine Bogs down at High RPM

Well that fuel line did not fix the bogging problem when I hit a wave. Since I was using my engine with choke to prime gas up to the motor could I have worn or stressed the diaphram. Remember I didn't kow I had a bulb so I used the engine and choke combo to always start even on the start of a new season. I replaced the diaphram 3 years ago.

 

[roscoe]

Re: Engine Bogs down at High RPM

Maybe.<br />Some of the gas we have available these days can also play havoc with the diaphram.<br /><br />Cheap enough to try as the parts are under $10.<br />I do mine every 3-4 years just to be safe.<br /><br />Double check all the wiring, especially up around the stator and flywheel. Perhaps a wire is grounding out somewhere and causing you to lose spark.<br /><br />?