low speed only 1978 evinrude 85 hp V4

[treenfive]

MY 1978 evinrude 85 hp v4 runs fine at low speeds, up to about 7 knots. When I advance the throttle all the way forward, that is all that I can get out of it. I looked at the linkage and everything appears to be advancing to the stops. I took off the air silencer and used a can of carb cleaner. It made the engine run smoother but nothing at full throttle. I have the engine on a 15 foot Starcraft American and figure that I should be able to get 40 knots easy.

 

[Solittle]

Re: low speed only 1978 evinrude 85 hp V4

You description of the symptoms points to crud in the carbs. Spraying a can of carb cleaner into the carb won't clean out the crud and can damage the engine if you spray it into a running engine. You should start out though by checking spark and compression. Follow that with a disassembly, soak, blow out with high pressure air and a new carb kit.

 

[spiked]

Re: low speed only 1978 evinrude 85 hp V4

i'm no expert here but i had a similar problem with my 90 hp motor. i found that my advance was not pulling forward with the throttle. i had to pull off the flywheel and clean all the crap out of the timing setup then it worked fine with the help of some lubrication too. i'm just passing on my experience, it may have nothing to do with what you have going on

 

[knucklecars]

Re: low speed only 1978 evinrude 85 hp V4

I had the same problem with my 69 Johnson 40hp, check for spark in both cylinders, mine was only firing on one...turned out to be a bad coil...wow what a difference!...only had about half power or less before...good luck!

 

[buddyholly]

Re: low speed only 1978 evinrude 85 hp V4

are you sure that the carb butterflies are opening all the way? also check your fuel pump,squeeze the bulb when trying to go full throttle and if it opens up it could be it.