70 hp no power

[trbeharris]

Hi all,<br /><br />I just purchased a 1977 3cyl 70hp Evinrude. It starts, idles and revs when not in gear, or under load. When I try to accelerate in the water (16ft aluminum) the motor strains and will not come to plane. New plugs, new gas, cleaned carbs with Evinrude carb cleaner, compression 120,120,118, new water pump assembly (engine running cool). The motor sat unused for 4 years, but roared to life immediately. <br /><br />Any suggestions where to start?

 

[red10]

Re: 70 hp no power

check that your coils are not cracked externally causing a loss of spark, i have a 75 70 horse that had the same problem

 

[Chinewalker]

Re: 70 hp no power

How did you clean the carbs? Did you spray down the throats with the carb cleaner or mix it in the gas? If so, neither way will clean up a gummed up carb. You MUST remove and disassemble the carbs to clean them. You are exhibiting classic gummed up carb symptoms.<br /><br />Also, have you checked for spark on all three plugs? Compression numbers are good, but do NOT run the motor anymore until you get the problem sorted out, as a gummed up carb means that cylinder is not receiving lubrication and things can come unglued in a hurry if you're not careful... It's best to go through all three carbs as one that's gummed up enough to plug the system means the others likely have goo in them, too.<br /><br />- Scott

 

[trbeharris]

Re: 70 hp no power

I used the carb cleaner down the throats. I have good spark in all three cylinders. Could the motor rev in neutral with gummed-up carbs?<br /><br />Thanks!

 

[jim dozier]

Re: 70 hp no power

The motor will rev up in neutral running on only 1 cylinder with a gummed up carb. Pull those carbs off and do a thorough cleaning/rebuild with spray carb cleaner AND compressed air. Install the rebuild kit and set the float and idle mixture to manual specs.

 

[Chinewalker]

Re: 70 hp no power

All spraying carb cleaner in the throats does is clean the throats. The bowls are where the gumming happens, plus all of the small passages, etc. Those carbs have to come apart. The other issue with running carb cleaner in an outboard (while running) is that it'll rinse the residual lubrication off the bearings, pistons and cylinder walls inside the motor. Not good! <br /><br />With no load on the motor, that engine will rev up fine on one, two, or three cylinders and to the untrained (and even a trained) ear, it'll sound just fine. <br />- Scott

 

[trbeharris]

Re: 70 hp no power

Thanks for the direction! I'll get into it tonight.