Power Drops Off at Higher Speeds

[DanFromDaHammer]

Hellooo!
Would anyone know why I would lose power at highter speeds? I have a 175 HP Evinrude V6 (1980) on a 16' Sidewinder and it seems to run VERY strong until I hit about 45-50 MPH and then power just drops off. It will actually shut off if I don't throttle back and keep it alive.
I just got it back from the boat shop where I had a spring maintenance package (linkages adjusted, compression checked, vacuum tested etc.) and the guys gave it a thumbs up.

Thanks a lot!

Dan

[Corpus Skipper]

You may have a fuel flow restriction. Check your fuel filters, hoses, and primer bulb. The hose can be tricky, especially if it's old. Sometimes the inner layer becomes separated and can be sucked closed with no indication from the outside. Also, make sure your fuel tank is venting properly. Good luck.

[DanFromDaHammer]

ah ... thanks. I'll check it out. I just bought the hose but it's connected to one of those small red 5 gallon tanks. I'm not sure it vents very well. I have a built-in big front tank but it has old, bad gas in it and I can't use it 'till I syphon it out. the guy I bought the boat off of in May said that the gas had been in there since Spring 04 ...... I can't imagine it's any good. That tank has a vent porting out the side of the boat so I know venting shouldn't be an issue there. Makes sense .. thanks again.

Dan

[woodboat]

Spring 04 is only slightly more than a year. It might not be the best but it may be OK with a little dry gas.

[marshmat]

Any odd noises as it dies? I'm not sure how many jets your carb has. The high-speed jets might be clogged, damaged or set wrong. This would cause a lean condition, poor running and loss of power as the throttle opened past the point where these jets should cut in. Check the fuel lines too as if they are damaged like Craig describes you may get enough fuel flow when slow, but at high speed the pump suction might collapse the lines. Good luck.

[DanFromDaHammer]

Thanks! I'll check 'er out this weekend. It has 3 carbs but like I mentioned I just had it in for maintenance where they supposedly gave the thing a once-over. It does run a whole lot better since I got it back though. You'd figure they'd notice something like clogged jets or the like right? Thanks again!

Dan