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1976 Evinrude 55hp wont idle

T

ToddL

New member
Hi Experts-

I'm having a hard time getting my 1976 55hp Evinrude to idle correctly. I've spent a lot of time and money rebuilding this thing and just can't get it to idle right.

For the ignition, I replaced the stator, both coils, the power pack, and plugs. The plugs are gapped at 0.03" and the timing set at 3deg but I had to give it a little bit throttle (~1200RPM) to keep it running. I had the advance linkage disconnected to do this.

For the fuel system, I rebuilt both carbs using new floats and needle valves. I tried to make sure all the ports were clean by blowing compressed air the them the best I could. I also changed fuel pump and the low speed needles and seats used to set the idle.

No matter what I do it seems that engine does not want to run smoothly below ~1100 rmp. With water muffs on the lower unit and at that speed I hear the engine surging (missing?) periodically. When I try to rev it, it just runs a little rougher than expected.

Is it possible that some of the smaller ports in the carbs are still clogged? I tried to clean all but some ports are very tiny.
Would this be indicative of my float level being misadjusted?
What should the engine idle at just using water muffs?


Is anyone willing to guide me thru this? I can make some videos if it helps...
 
Take a look at the spark plugs. Are they wet with fuel? water? dry? oily? tan? It helps with the diagnosis.
 
RGP said:
Take a look at the spark plugs. Are they wet with fuel? water? dry? oily? tan? It helps with the diagnosis.
Click to expand...

Sorry, I already had the carbs back off before I saw your response so instead of giving inaccurate info I do not know the answer to this question just yet.

But... after removing the carbs I noticed one of the floats was not level any more when I turned it upside down. When resting on needle it would have allowed the bowl to fill more than normal. I'm not sure how the engine would have responded to this but I fixed that so it should shut off now when the float is parallel with the surface of the bowl's edge.

Next, I removed the idle needles, retainers, and seats. One of the needles appeared to be ever so slightly bent to one direction. Also one of the seats appeared to be slightly cracked. I installed them myself when I rebuild the carbs. I did it without a special tool to insert the plastic seats. Maybe that's part of the issue too. Is there a way to do seat these down inside the hole without a special tool? I think I just put them on the needles and screwed them in before. Both needles and seats (and retainers) were new when I rebuilt the carbs so whatever happened I did it somehow.


There's also some jets down inside the bowl that look like they can be unscrewed with a flathead screwdriver thru the drain plug hole. I was afraid to take them out during the original rebuild but would like to replace them if they need it. I just want it to be right this time so I can fish for a while instead of the endless fix ...

Thanks for your response.
 
Those are high speed jets at the bottom of the bowl. Be sure they are clean. They will come out thru the drain.

I can't comment on the seat install. Don't know correct procedure.

Part #39, nozzle gasket, in carb diagram is in place OK?

Pull the plugs and take a look. They will still tell the story of the last time the motor was run. It might help zero in on upper or lower carb trouble.
 
RGP said:
Those are high speed jets at the bottom of the bowl. Be sure they are clean. They will come out thru the drain.

I can't comment on the seat install. Don't know correct procedure.

Part #39, nozzle gasket, in carb diagram is in place OK?

Pull the plugs and take a look. They will still tell the story of the last time the motor was run. It might help zero in on upper or lower carb trouble.
Click to expand...

I just pulled the spark plugs out and they are slightly wet with gas. They are light tan on one side of the insulator and turning black on one side with what looks like soot.
 
To claify my terminolgy from before:

The "Seat" that I mentioned is actually called the "Needle Valve Bearing"
The "Idle Needle" is actually called the Slow Speed "Needle Valve"

The Slow Speed needle valves look good and it's hard to tell if one is really bent or is an optical illusion. If it not obvious, should they be ok?

If the Needle Valve Bearing is just a bearing and not a seal, should they be ok?
 
plugs both look the same? Two carbs, two cylinder, I thought this might direct you to one or the other carb. Guess not.

Next time you start it, try disconnecting the throttle linkage that connects the two carbs together. Blip each throttle independently and try to see if one carb is happier than the other.
 
Is it possible that some of the smaller ports in the carbs are still clogged?
Click to expand...
Soak the carb bowl overnight in carb cleaner or lacquer thinner. Blow out the circuits w/100 PSI compressed air. If they still seem plugged probe the circuits w/a strand of fine copper wire and reblow w/air.
 
guyjg said:
Soak the carb bowl overnight in carb cleaner or lacquer thinner. Blow out the circuits w/100 PSI compressed air. If they still seem plugged probe the circuits w/a strand of fine copper wire and reblow w/air.
Click to expand...

I popped out the core plug #5 and exposed the slow speed chamber and the three little holes for the idle. All looks clean, like new, in both carbs. I just happened to have the spare plugs from the original rebuild kit and I'll reinstall them tomorrow. I'm convinced that the carb and all it's orifices are clean.

I'm thinking this could have all been due to the misadjusted float level I spoke of earlier. If one bowl was overfilling does anyone know how the engine would respond? Would that extra fluid in one of the bowls end up flooding one of the cycliders effecting my idle somehow? On one of the carbs the float was level when resting on the needle. On the other carb the float was at an angle. It was just below the edge of the bowl on the right side when resting on the needle on the left side which I know is way off what it's supposed to be. Could this cause that much havoc?

A side question: Has anyone ever experienced a faulty reed valve assembly before? It looked ok when I was rebuilding the motor but don't know if they ever need replaced...
 
Last edited:
RGP said:
plugs both look the same? Two carbs, two cylinder, I thought this might direct you to one or the other carb. Guess not.

Next time you start it, try disconnecting the throttle linkage that connects the two carbs together. Blip each throttle independently and try to see if one carb is happier than the other.
Click to expand...

I think I know what you mean by 'happier' but can you clarify a little? If one cyclider is throttling and other is not will it run smoother throttling the "good" one than the bad one? I've never tried this on only one cyclider before.
 
motor will respond instantly to a good carb. Will stumble and miss on bad carb.

Purpose is to isolate bad carb. Your ear will tell you.
 
Was flywheel torqued properly after it was off ?----------Timing involves setting the MAXIMUM timing advance at full throttle.--------Idle timing is / can be confusing to some folks.------It is the where the throttle plates start to open up !!-----Actual timing on an engine that idle smoothly looks after itself , the further retarted the better it is.----
 
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