Force 125 cuts out above 4000 rpm

[pastorbud]

My 1987 Force 125 hp idles and runs good, starts easy, and accelerates ok out of the hole. But.... it begins to cough and sputter if I leave it at wide open throttle; it will intermittently drop down to 3500 rpm, then surge back up above 4000. If I back off just a little, and run at 4000, it seems to calm down and run OK.

And here's the weird part... the problem seems to really get exacerbated in rough water or turns. Wasn't sure I was gonna get back in from the Fisher's Island sound today in choppy water.

A friend told me this was sometimes an indicator of a fuel line leaking and sucking in air. I replaced what looked like a deteriorated section of fuel line going from the fuel filter to the fuel pump, but the problem endures.

Maybe sludge in the fuel tank? Dunno. Boat did not do this when I bought it this spring, but it seems to be getting worse now. And the bluefish are biting!

It's on a 1987 Bayliner, 19 foot center console.

 

[bentle]

Re: Force 125 cuts out above 4000 rpm

Check all hoses from tank to motor. Looking for any cracked or corroded hoses or connections. Also check pick up tube in tank.

 

[Jiggz]

Re: Force 125 cuts out above 4000 rpm

Check the entire fuel system starting from the pick up tube all the way to the carbs and the return lines. And then you also need to make sure the fuel pump is working properly and delivering the right amount of fuel which means the diaphragm may not be working to specs. Install a see through fuel filter between the fuel pump out hose to the carbs. Any sign of bubbles indicates a leak in the suction end of the pump. If there are no bubbles and the problem stays the same, but with the fuel filter not full, it's most likely a faulty fuel pump diaphragm. Or with the fuel filter staying full and the priming bulb staying hard, it could be improper float setting.

 

[foodfisher]

Re: Force 125 cuts out above 4000 rpm

Check for a wire that could rubbed bare up around the flywheel. Rough water and accelerating might be swinging it to a ground of some kind.

 

[mikes 86]

Re: Force 125 cuts out above 4000 rpm

needle sticking in seat, was my problem acted the same

 

[pastorbud]

Re: Force 125 cuts out above 4000 rpm

Did the fuel lines and checked the pickup tube. Took it out this afternoon and it ran a LOT better! There was no filter screen on the pickup tube; was there supposed to be? My old Mercruiser had one.

I also added the inline fuel filter and it seems to be filled up and clear. Couldn't check it running wide open, since I had to drive the boat.

It still "backs off" and surges at the last few degrees of wide-open-- which gets me up to about 4700 RPM (I can't adjust the trim, so I'm not getting top speed out of it).

But she's good up to 4500, which is fine with me. I usually run about 4000-4200 to save fuel. Gets me to the fish in a reasonable time.

I do have a "shaggy dog" story on the carb floats, but I'll post it later. Bottom line, I've had a hard time finding a carb rebuild kit to fit these carbs, so I've got a combination of new floats and old needles. And the original seats. More later on that.

It was dripping a little bit at idle, so the float is still not right. But it just started doing that so... I put GumOut in for now. That and a couple of magic bean stalks oughta do it!