what am I overlooking

[smithbader]

I have a 1988 evinrude 110hp. runs fine up until about 3800 rpms then begins to slow down then speed up, slow down and continues this until I slow down and then once under the 3500rpm threshold seems fine. replaced fuel line, cleaned filter,checked all connections everything seems fine. It feels like it is a fuel delivry issue. replaced fuel pump about 2 weeks ago and everything ran fine until this weekend. any help would be greatly appreciated.

 

[AEROCOOK]

Re: what am I overlooking

Have someone repeatedly squeeze the primer bulb in the fuel line while running at high speed and see if it runs any better.
If theres no improvement I'd take the carbs off and clean them.

 

[EricJRW]

Re: what am I overlooking

Who replaced the fuel pump and is there a filter after the pump?

I know that second question may be odd, but my engine that once had a VRO now has a fuel pump (and now I pre-mix), but apparently the "old" filter was left in-line. I learned this recently, and continue to use it, even though the fuel pump has its own screen filter. The reason I ask if that if the pump replacing left a chunk of junk in the lines, it could easily end up blocking something (HS orifice, jet, nozzle, etc.).

 

[Daviet]

Re: what am I overlooking

I would pull the high speed orifices and check them to see if they are plugged or restricted.