1984 Johnson 90hp Speed/Power Problems

[Boat84]

Hi, Everyone this is my 2nd post. My first post was 2cylinders missing, and that was caused by a pinched bottom gas line, so now i'm on the water and atleast moving : ) I have a 1984 Procraft 1650V it's running 40mph @ 4500RPM WOT Seems like it should be doing more than that. When I took it out after fixing the pinch gas line I didn't have the TOP on it or the cap that bolts in front of the Carb it Seemed like it would tack up to 5200RPM pretty good without that stuff on it. But now with the cap installed and the top on it 4500RPM is all i'm getting..I have a friend that has a 15ft bass boat with a Evenrude 70hp and he blew me out of the water running about 45mph this to me doesn't seem right. Anyone have any idea why so slow are is this normal for this type of boat.

 

[fireman57]

Re: 1984 Johnson 90hp Speed/Power Problems

You said that you are only getting about 4500 instead of 5300 so I am supposing that you have a tach for these numbers. If having the hood on is the only difference then I would suspect an exhaust leak at the base of the powerhead. The way to test for this is just like you did. Hood off and go faster. Hood on go slower. Exhaust leak most of the time. Glad these guys got you going the first time, but honestly you should have found the pinched gas line (humor). To change this gasket you will have to remove the powerhead so get a buddy to help you lift it off and back on squarely so you don't tear the new gasket.