1977 Evinrude 75hp

[pontoonpat]

engine is in Great condition, I haven't run, because I was saving, for another, boat project..I've been working on. Has been sit'n, in-doors, for about, 5yrs..) Ran this past weekend, on fresh tank of gas. started, on 3rd, crank. idle, needed adjusted..Ok. Put boat in water, didn't have any froward, speed (ran like a 10hp, instead of, 75hp). had throttle, wide open..just no power.. Plugs were, amazingly clean, (bottom one, was, a little, dirty. cleaned, and, re-used) Engine ran, but, just no power....It would surge, from time to time, while underway, like it, wanted to run, faster. Same, as, when, idling...like I was, hit'n, the, accelerator, in a car (rev-up & down, just for Second's, without me, touching, anything.)..any kind of suggestions, on where to begin, would be, much appreciated..thanks!

 

[boobie]

Do a compression test on it.

 

[flyingscott]

And a spark test.

 

[racerone]

Clean the carburetors.----Put new diaphragm in the fuel pump.

 

[Faztbullet]

If you didn't pickle the carbs they need going thru now.

 

[spybot]

After the spark test. Check each plug is actually sparking. I had a similar faulty on a bigger engine. I checked spark at 7/16th
Jumped this easy but i didn't check if the plug was sparking. This gave me a False Positive :facepalm:
I spent another 2 weekends trying to trace a fault only to find a dead plug.

 

[oldboat1]

Get an open air adjustable spark tester at an auto parts store to measure spark on each lead -- tests magneto strength. Get a couple of fresh plugs (Champion L77JC4). The CD2 power pack for that motor is $60 to $70, which is not outlandish imo.

When buying the spark tester, you can see if the store will lend out a compression tester -- should check that before anything else.

 

[pontoonpat]

Advise, Much Appreciated, From All !!!!! Thank-You!...Stay, Safe!