Evinrude 1980 60hp misfire

[alangranton]

Here goes,
I have good compression both cylinders and a very strong blue spark.
Starts really well
idles , but has a backfire sort of loud pop from the exaust.

So I tried putting the timing strobe on the leads and the coils are delivering as they should.

Now I removed the plugs and the top cylinder plug is clean as it should be.

The lower cylinder plug is black with carbon, very black.

Does this mean over fueling from the carb and then burning ritch, then fuel in the exhaust then back fire?
If so any ideas on a fix.

Cheers Alan

 

[Silvertip]

Re: Evinrude 1980 60hp misfire

Carbon fouled/blackened plugs can be caused by a cylinder that is not firing properly (hence the popping), or it may be a carburetion issue. Just because you have spark does not mean the cylinder is firing. Did you replace the plugs and see what happens. You said there was good compression, but was a compression check actually performed?? Are you sure the engine is running on both cylinders. Some folks can't tell the difference. (No offense -- I'm just asking!!)

 

[alangranton]

Re: Evinrude 1980 60hp misfire

This is the test I did

cylinder 1

cylinder 2

 

[Daviet]

Re: Evinrude 1980 60hp misfire

Those carbs are nonadjustable, might be time to remove and rebuild them, paying attention to all the orifices.

 

[clemsonfor]

Re: Evinrude 1980 60hp misfire

First is the top plug too clean? I had the though of water getting into the cyl. The other thing is to swap the plugs and see if the top one gets clean and bottom one fouls. Carbs do have no adjustment i have the same motor, well an 81 model but still. Or clean them both with gas and a wire brush and put them back in, hot carbon could be igniting and causing premature fire. This is how the motor will runaway to with no ignition is that carbon lights the fuel off till it blows or runs out of fuuel

 

[alangranton]

Re: Evinrude 1980 60hp misfire

I wil get some pictures of plugs posted on here tomorrow night -England- 22.00 now and I'm knackard I need my bed

 

[clemsonfor]

Re: Evinrude 1980 60hp misfire

I wil get some pictures of plugs posted on here tomorrow night -England- 22.00 now and I'm knackard I need my bed

What? I gues your in england and your saying it 22:00 and your tired.

 

[alangranton]

Re: Evinrude 1980 60hp misfire

What? I gues your in england and your saying it 22:00 and your tired.

Absolutly.....now I'm at work - Teacher and the kids are on a break.

I'm still worried about my plugs and their condition.

 

[charles1974]

Re: Evinrude 1980 60hp misfire

I had the same issue on a Evinrude 40hp that drove me nuts. Turns out it was the plug wire terminal on the coil that was corroded and once I cleaned that the motor ran AWESOME. I guess under a load the corrosion made the plug not get enough spark hence the backfire. Just a thought..

 

[alangranton]

Re: Evinrude 1980 60hp misfire

Many thanks, I took your advice cleaned a few contacts.

I also took the other advice, took the carbs apart cleaned and reassembled.

Loads of black petrol (I Think) out of one of float chambers. The same carb feeding the fowled plug.

Miss fire now gone and running better.

Now i am dizzy with 2 stroke fumes, i'm going to sit on my the couch and look at boats I can't afford on ebay.