1976 Evinrude outboard not running right

[Fiddlefire]

This motor has not been running right since I bought this boat. Here are the symptoms. The idle is erratic and is always changing. Every once and a while I can get her to idle okay. When I throttle it up from the remote then return back to idle the idle will not return to normal and will idle high until I manually move the spark advance lever back to its position to where it will idle. That is problem #1. Next issue use to be when you would throttle up hard she would bog down and die. About 90 percent of that problem got better after rebuilding all 3 carburetors, Replacing all gaskets in the silencer box. Now here is an interesting point. After rebuilding the carbs, The motor ran better with the silencer box off. When I put it into place the motor had a harder time starting and would pop and cough and did not do that with it off. FYI, with extensive research from trying to order gaskets I came to the determination that the silencer box is off of a 1986 motor but fits in place fine. I also replaced the middle cylinder spark coil because the spark plug wire would not stay in place and the fuel pump was replaced with all of the fuel lines while everything was apart. One thing that I haven't played around with is spark advance and timing. The model # of my motor is 70EL76D. Any advice would be great at this time. HELP!

 

[racerone]

Compression test values should be posted.----Timing normally requires no adjustment. Adjust black thingy on the cable so that throttle is pulled against the stop with a little preload.

 

[Fiddlefire]

It may take a while to find a compression tester but shown here in this picture shows a similar motor to mine. I have a black arrow showing the piece that that I manually push back(to the left) in order to get the idle to come down. I have been messing around with that adjustment on the cable but I also disconnected the throttle cable from the remote on the motor side leaving it out of the picture so It doesn't seem that the black adjuster seems to be part of the problem. That's the only reason to think there was a timing issue, wasn't sure. At first I was thinking that there may have been a problem with the coil spring inside the unit below the arrow but she seems to have plenty of tension but not understanding why that arm doesn't return to idle position. You can see in the picture that the entire arm is straight up and down and mine is not when it goes back to the idle position by itself causing the idle not to return to what seems to be the normal idle position. I hope that this all makes sense. I have some pictures that I need to dig up so it might give a better idea of what it is doing. Talking in person would be easier to describe this as well but not sure if this can be done or not.

 

[racerone]

The black thingy adjusts to make the arm go to the stop.-----If it does not there is something else wrong.---I have worked on more than 1 of these motors.

 

[Fiddlefire]

Okay, just to make sure I know what you mean about the black thingy I drew an arrow at the lower left side of the picture on the cable itself. Is this what you are talking about?

 

[racerone]

Correct.

 

[Fiddlefire]

Thanks that will work. Getting a loaner compression tester in the next few days.

 

[boobie]

If you can find an old OMC dealer who has his old service bulletins there was one on that motor for carb mods that really improved the performance of that motor. I've done some years ago and they worked out good.

 

[Fiddlefire]

Hmm Interesting. There really isn't anything around this area unfortunately. Maybe I can find something on line or someone on this sight has some knowledge about this. I could check YouTube as well I guess.

 

[Fiddlefire]

Hey racerone, I did a compression test on the motor last night and seems to be okay. Cylinder 1 - 119 PSI #2 115 PSI and #3 120 PSI. I'm going to try and work the throttle cable issue after work making that adjustment that you suggested. I am also working that issue still that I am having with the engine running better with out the silencer box installed. That's a weird one, film at 11 !