1989 Evinrude V4 120 wont run at WOT
I am very familiar with working on SST45 motors but not the newer motors with VRO pumps & this has me stumped.
I bought this boat this winter. It was sitting outside in the pacific northwest & probably sat out all the time with the prior owner.
I have no other history on the boat except it supposedly ran fine before winter.
When I first got it I could not get it to start well or idle.
There were mismatched spark plug wires on it with no continuity.
I changed all the wires, plugs and It starts right up and idles fine now.
I thought problem solved.
Took it out for the first time & towed a tube around all day running great.
Towards the end of the day the rpm dropped off like it was dropping a cylinder & would not run at WOT anymore or pull the tube.
Speedo went from 42mph to 30 mph at WOT.
When I choked it the rpms came up & the speed picked up.
Choking it repeatedly would bring the rpm & speed up to near normal until you stopped choking it repeatedly & than the rpm & speed drops again.
Seems like it is a fuel problem.
I drained the tank, ran it out of fuel, put fresh fuel in it with stabil, took the carbs apart and blew all the passages & jets out.
When that didn't do it.
I took it out with the air cover & hood off so I could spray WD40 around the base of the carbs to see if there was a leak.
All I got was ringing ears & no indication that there was a vacuum leak.
Carbs & throttle plate were not even warm actually cold to the touch.
Cylinder heads are warm but you can hold your hand on them so I am sure it is not getting hot.
It's got about 130 lbs. compression & even on all cylinders.
The only other thing I noticed while running it with the hood off is the fuel filter goes practically empty.
I don't know if that is normal or indicated a fuel pump issue.
Pumping the squeeze bulb while running it & keeping the filter full did not seem to make a difference.
It sure seems like it is a fuel problem but I don't know how the VRO pumps work & if the VRO pump might be the problem.
I was told by the local mechanic that if the VRO pump went bad it would go rich & smoke a lot.
It does not have any excess smoke.
Anybody else seen this problem or know what it might be ?
