1991 Evinrude 140hp low power

[High Floater]

After setting for 9mo, I ran my motor on hose for 10min then lake tested it. It would not make full power only about 3500rpm. I pulled plug wire one at a time and found droped cylinder. I replaced all plugs (Champion QL77CJ4 0.030in gap) and coil on bad cylinder. Retested and would not rev above 2000. I checked compression 135 to 140psi on each cylinder. New fuel separator and filter and rebuilt carbs. Retested and boat ran liked scalded dog for 10 to 15 sec then bogged down to 2000rpm I would pull throttle back and then open it and engine would climb power curve for about 3 to 5 sec.It then ran for about 15 to 20 sec with rpm going back and forth from 2800 to 4000rpm. After 3 or 4 min it would not rev above 2000.It now seemed to be idleing rougher than than when cold. I hooked up fuel pressure gauge and pressure was 4 to above 10psi througout rpm range. Retested and same problems as before; progressively ran slower and slower and idled rough. Fuel bulb stays full and good press all the time. Could this be the power pack? I do not have a repair book for this motor.I have ordered one. Does some one know the wire colors and ohms for sensor and charge coil and isolation diodes.<br />I would appreciate any help anyone can offer.

 

[JB]

Re: 1991 Evinrude 140hp low power

Hi, Floater.<br /><br />Sounds like some sensor is putting your engine into S.L.O.W.. Can't guess which one or why without a lot more info.<br /><br />Let us know what you find.