70HP 1970's Evinrude Motor.

[Clydeywidey]

Hi, I just recently rescued a old speedboat from down our road ( It has been sitting there for 5-8 years apparently). We just put it in the water yesterday, After we finished painting, Re-carpeting and other fun stuff! We put it in and it idles very good, Shifts gears great, No stalling when i do that. When i push the throttle down to full tilt, It accelerates and then dies down back to an idle after about 1 second of lifting the nose out of the water, If i shift it back into Starting position (N) then put the throttle back up, It does the same exact thing ( Gets power for about a second, then dies down again to idle speed). I have some background with OLD outboard motors as i have a 1971 60HP on my 1965 Trihull speedboat ( That one runs really good) and some other 1970's 5-6.5HP Small outboards. I am going down to the cottage to run ears on it in a few minutes to see if it can go full blast without any load and will see if that works. I am thinking some of the pipes could be just clogged after 5-8 years on the shore without being maintained, And am hoping that just putting runtime and gas through it will help, I will update when i get back home. Any feedback is appreciated, Thanks.
Sam.

 

[Joe Reeves]

Re: 70HP 1970's Evinrude Motor.

Running "full blast" (full throttle) without a load, exceeding the top rated rpm, or even exceeding 1800 rpm on a flushette is inviting a runaway engine. Shoud this happen, and it does.... but the time you figure out how to shut it down, connecting rods are usually flying out the side of the powerhead.

Sitting that long.... remove, clean, and rebuild the carburetors, and make sure that you clean the high speed jet manually with a piece of single strand steel wire.

 

[Clydeywidey]

Re: 70HP 1970's Evinrude Motor.

I just got back, We ran it out of the water and it rev'd up high and the throttle didn't come down on its own. So what i have found out for a fact is that, The motor will power up and after about a second will go back down to a idle ( when it is pushing the boat ), When its out of the water it will hold high RPM. So any suggestions on how to go forward? Cleaning carbs? Anything else? Any tips help! Thanks

 

[egclassic]

Re: 70HP 1970's Evinrude Motor.

Like others have stated here before, running on muffs only tells you that the engine will start. I have come to realize this myself many times. However, you should NEVER run a motor at high RPM's on muffs, ever.
You mentioned how you painted and recarpeted this boat that has sat for years, but no mention of doing what really matters, checking the motor out. Have you rebuilt/cleaned the carbs, checked all fuel lines, rebuilt/cleaned fuel pump, lync n' sync'd, check compression, any of this? That where I'd start, not exactly in that order!

 

[boobie]

Re: 70HP 1970's Evinrude Motor.

Check your compression and then your spark on an open air gap spark tester. If they both pass, then do the carbs.

 

[Clydeywidey]

Re: 70HP 1970's Evinrude Motor.

Thanks for all the responses! I will clean the carbs , Check compression and check sparks this weekend. Once i do all of those things i hope it works, if not i will be back!
Thanks again.
-Sam