1996 Evinrude 175 Ocean Pro won't run over 4,000 RPM

[3rdWish]

I have had this boat & motor for 6 years. I used to be able to get 5,000+ rpm and 43 MPH. Last summer it started running 4,000 max and only about 32 MPH. I would also occasionally bog down a WOT and wouldn't run over 2,500 to 3,000 RPM. My mechanic has replaced both coils, rebuilt the carbs, new fuel pump, filter and water separator. The primer & fuel lines from the tank to the motor have been replaced. The VRO was disabled before I bought the boat, and I asked the mechanic to check all the lines to make sure no air leaks. He has checked the plugs, timing, and electrical system. He has also ridden with me and checked for overheating with an infrared gun to see if it was running in safe mode. Also, I have not changed props.

Any ideas what to check next. We are pretty much stumped. Thanks!

 

[Chris1956]

Re: 1996 Evinrude 175 Ocean Pro won't run over 4,000 RPM

You take a compression test? Is compression same as two years ago? Is it even across all cylinders. Iis the prop dinged up?

 

[boobie]

Re: 1996 Evinrude 175 Ocean Pro won't run over 4,000 RPM

As said above, do a compression test. Will the spark jump a 7/16" open air gap on a tester ??

 

[3rdWish]

Re: 1996 Evinrude 175 Ocean Pro won't run over 4,000 RPM

Guys, thanks for the quick replies especially on a holiday weekend! I just asked my mechanic about the above and he has done a compression check and said it's fine, also has checked the spark. I mentioned to him that my primer bulb never stays hard and I have to prime it again even if I've only stopped for 20 or 30 minutes, which I thought I had mentioned before, but apparently not. He's going to pull the pickup from the tank and check for obstruction on the screen. I'll let you know if that is the problem.

 

[bullcity101]

Re: 1996 Evinrude 175 Ocean Pro won't run over 4,000 RPM

sounds like the output of the fuel pump is of concern, air leak maybe.