70hp Force surges at WOT

[bigbluedog]

'92 70 HP FORCE surges slightly at WOT and only at WOT.<br />Starts right up and will run all day. Even runs all day at WOT but surges.<br />I just put new tanks and gas lines and bulbs on boat. HELP!!

 

[eurolarva]

Re: 70hp Force surges at WOT

Did you replace the fuel lines because of this problem or did it happen after replacing them? Check for spun prop. Make sure both carb butterflies are not going beyond fully open. The throttle butterflies should only open 90 degrees. If they go beyond this point they will start to close in the opposite direction. Could be a mis adjusted carb float or even a clutch dog or gear in the lower unit going bad. Check the carb and the spun prop first.

 

[bigbluedog]

Re: 70hp Force surges at WOT

The primer bulbs were sucking flat, my logic was to replace them and also the tanks as they were older (92).<br />I would suspect a spun prop if rpm would raise but its not. It only drops then comes back up and only hardly noticable but it drives me crazy because I can "feel" it.I only have one carb on the 70hp and I've checked for wide open butterfly and thats ok. My other line of thinking is that I have a missfire that only rears its ugly head under full power... possibly a weak spark.

 

[ackman]

Re: 70hp Force surges at WOT

"The primer bulbs were sucking flat..."; did you have this surge problem before replacing fuel lines etc.? A misfire even at WOT should "feel" different then a fuel delivery hiccup.