Evinrude 1977 55hp Accelerates out of control

[RubyCreekTed]

Hello All, First time post. I recently bought this boat/motor. Have been trying to get it to run good. I bought a set of manuals and have been making progress. Yesterday it started to accelarate out of control when I get above a certain rpm. It just stops responding to the throttle and runs away. the only way to stop it is to choke it out. Turning the key off doesn't stop it. The throttle is closed on both carbs and it still runs at high rpm until I choke it out. What could be the cause of this? How can it run at high rpm with the throttle shut down to idle? The key shuts it down fine until the point where it runs away. I tried to search the forum but couldn't seem to get any hits. Thanks for any ideas you all can provide. RubyCreekTed

 

[kenmyfam]

Re: Evinrude 1977 55hp Accelerates out of control

Are you running on muffs or in the water ??

 

[5150abf]

Re: Evinrude 1977 55hp Accelerates out of control

Rule #14- DO NOT EVER run an outboard above 1500 rpm out of the water.

You are lucky to still have a motor to work on, running the motor fast without resistance can throw rods or pistons, very bad, idle or just above only, I was new once and did the same thing so don't feel bad just stop doing it.

The condition you mentioned is called run away and yes it can happen, alot of time it is caused by carbon build up in the heads, the carbon gets really hot and ignites the gas as soon as it enters the engine kind of like a deisel engine.

Search FAQs for DECARB, it is really easy and will make the engine run much better.

You are running this on ears I assume?

What problems are you having, someone here may be able to help.

 

[RubyCreekTed]

Re: Evinrude 1977 55hp Accelerates out of control

OUCH!! Thanks guys. I was using muffs. I sure hope I haven't damaged anything. I guess the next step is to see what it does in the water. I was fighting a problem with it running at slow speeds. So if I broke rule #14 where can I find these rules? Anxious to learn.
More symptoms from original problems.
The motor didn't want to idle gown low and we were having trouble shigting into gear without it dying. How low must you get the rpms before shifting into gear without hurting the gears? I think we were trying to get the rpms too low before putting in gear.
The motor seemed to be hard to start when hot. My nephew is a whiz with outboard carbs and we took the boat over and he pulled and cleaned both carbs and said they appeared to be in good condition and didn't really look dirty. The boat ran better after this but we still had trouble getting it in gear without killing the motor. I put new plugs in and gapped them to .040per the manual verses the .030 on the old plugs. I did an ohm check of both coils. The primary was hard to read since the spec was just 0.1 ohm and it looked ok. The secondarys read about 1900 and 2300 verses the spec of 1300 ohms. These were cold readings.
Yesterday before the runaway conditions I had the motor running really well although I don't if it was done to trolling speed since I was out of the water.
I think I will get some seafoam and decarb it in the water and run it a while and see what it does then. THANKS

RubyCreekTed

 

[kenmyfam]

Re: Evinrude 1977 55hp Accelerates out of control

OUCH!! Thanks guys. I was using muffs. I sure hope I haven't damaged anything. I guess the next step is to see what it does in the water. I was fighting a problem with it running at slow speeds. So if I broke rule #14 where can I find these rules? Anxious to learn. RubyCreekTed

Best thing you can do is tell us all the symptoms and what you have done so far. Then get some feedback as to where to go from there.