1986 Evinrude 110hp V4 won't do more than 2500rpms

[vineyd]

I was hoping I could get some help with my motor. I bought a 18'7" sea gull power catamaran with the 1986 Evinrude 110hp V4 mounted on it about 6 months ago. I'll try to keep this short but give relevant information.

Boat would do 35-40mph but idled rough at trolling speeds. Mileage seemed really low ~ 1-1.5 mpg at 4500-5000rpm. Other than rough idle ran great.

I had it out fishing in a flats area, ran into some sandy mucky bottom but not enough to stall the motor, early in the morning. At one point a rope fell overboard and tangled the prop at trolling speed. Immediate cut the engine and unfouled the rope. Only 2-3 wraps around the prop. Ran fine all day., fuel gauge was broken, ran out of fuel about 200yards from the dock. Filled the boat and set in the following day. Motor gunned with barely any throttle ( about 1 inch forward) but from that point on, it would not do more than 2500 WOT. It ran smooth and idled great. I took the boat to the shop. They check compression, fuel, fuel lines, bulb, fuel filter, and everything came back great. On muffs the throttle works great, no rough idle, no excessive smoke. Under load it will not go over 2500rpm. Can someone help me? Thank you very much

 

[emdsapmgr]

Re: 1986 Evinrude 110hp V4 won't do more than 2500rpms

Those engines were never very fuel efficient. Rough idling can be an internal carb problem. If the idle passages get clogged with dried fuel over the years, it can occasionally miss at idle. Once you crack the throttle off idle, other jets provide fuel and it may run just fine. A sudden drop in performance could mean that a spark plug has quit firing. It happens. You can perform a simple rpm drop test. Run the engine on the trailer (on the muffs). Use a pair of insulated pliers and pull one of the spark plug wires off one plug. The rpm's of the engine should decrease. Put the wire back on the plug, and pull another. Etc, etc. If you pull one plugwire off and the idle does not change, likely the plug is not firing. An inductive timing light will show similar results.