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1978 79HP evinrude throttle

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Edson16

New member
Was told motor will not idle unless throttle is about half way and it warms up than the motor will take off. I have not tried the motor yet as I just got it before winter hit..Trying to get info so I have an idea where to start looking. Thank you.:confused:
 
Welcome....Wow, could be simple, could be complex. First off is it a 75 horse?....that would be 3 cyl.....the 85 would be a V4. Check spark, compression, then fuel.
 
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Sorry for the wrong info. It is a 1978 70 HP Evinrude Long Shaft outboard. I apologize for the mistake and I can not find any way to edit the post.
 
No problem....now let's figure it out. First gotta remove fuel supply, then let's check spark. Remove all spark plugs, then...with a fully charged battery (12.65 v ), spin it over and see if spark will jump from the #2 Phillips screwdriver (which is pushed into the spark plug boots, one at a time)....and hold shank of screwdriver about 1/2" from a ground, (like headbolt). Should see a white/ blue spark at least 7/16" and even 1/2". Don't get shocked.....hold screwdriver only by the handle.....have a helper. Next we will check compression......do you have a gauge you can borrow?
 
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Re: 1978 70HP evinrude throttle

was lucky enough today to talk to the guy I bought the motor from. Says motor has a mind of its on. Told me hen he got the motor to idle and arm up he would be traveling at 1/4 throttle and then the motor would just take off at open throttle without touching it. Can not do anything right now because it is stored for winter up here near Ottawa Canada. compression was over 125 in all three cylinders. The one thing I noticed was it had two different brands of plugs in it, 2 champion and 1 I think was an autolite but not sure.
 
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Re: 1978 70HP evinrude throttle

Yes, winter here too, but I start taking work by late March. I expect a good year as more and more people are coming here for fishing and boating.....since Canada is closed up. That should be a good motor with that kind of compression. The motor you have typically develops a binding at the throttle arm pivot area on the starboard side. It needs to be dismantled and cleaned off from the sticky wear particles. Then re-lubed with good quality grease. I use Amsoil synthetic red grease. As you may or may not know, this arm activates a secondary lever that in turn advances the carburator butterflies, that secondary movement is accomplished by a spring....so if anything is binding, you may get a delayed throttle advance.
 
Re: 1978 70HP evinrude throttle

Thank you for your help. We have been in Duluth many times. Do you recommend any specific type of grease or lube to use on these pivot points? I am trying to locate a picture of the linkages to see what you are are mentioning. Again thank you and I will keep you informed on my progress ( seek more help ) on this motor.
 
Re: 1978 70HP evinrude throttle

I recommend Amsoil synthetic red grease. Because this arm pivot tends to build wear particles and stick, I use only the highest quality grease. Restoring the older motors has been a passion for me going on 55 years now and high quality grease is so very important. Grease can "chalk up" over time, and cause troubles. I'll see if I have a photo of this part here on my phone. Take care and tell your friends about the forum. We have techs here, many retired status, with thousands and thousands of combined years of professional experience, ready to help those who simply ask. Parts also are right here, just a few "clicks" away.....and with a very reasonable price.
 
Re: 1978 70HP evinrude throttle

A photo would put me in the right place. I have tinkered with motors but never really dug deep. Is there a link to the parts. Looking for a side mount remote control. Does this motor have an eight plug power plug on it.
 
To Timguy. Would this motor have a red plug on it for the electrical? Would you happen to know where I could get a side mount control box for this motor. When I bought the motor in the fall we could not get the control box off so I am getting it in the spring when he takes it off and gets his new Merc. The control box is a top mount so I want to sell it or trade for a side mount. Thank you.
 
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