1974 evinrude 115hp running question???? Help!!

[racerone]

Roj115------It was suggested to check for ORANGE wires going to the coils.---No response !----------It has been suggested to check for spark that jumps a gap of 7/16" and the response to that was that the motor has 13/16" plugs.

 

[Roj115]

I know those motors well and I'll lay odds that this is a spark problem. If it's starts and runs, it's got fuel. The way those motors are made, if it's getting fuel to some cylinders, it's getting fuel to all. 100 to 1 it's not on the fuel side.

Check all the simplest things first. Try new spark plugs, check all leads going to the coils, check continuity on the spark plug leads, swap out each coil one at a time with a known good one, etc. I've been down this road more times than I care to admit...

My guess is it's most likely either a bad spark plug, a bad spark plug lead, a broken or disconnected ground wire on a coil or a bad coil.

Pulse pack, possibly but the ones on that motor tend to go completely if they go at all but it is possible that they can fail partially so some cylinders get spark and others not. Most of the time they just die completely so if it's got spark, which it does in this case, it's probably not the pulse pack.

 

[racerone]

?????-------Roj115,are you absolutely sure about---- " if it is getting fuel to some , it is getting fuel to all " on this motor?-----What if a high speed jet was plugged in one carburetor bowl ?

 

[Roj115]

?????-------Roj115,are you absolutely sure about---- " if it is getting fuel to some , it is getting fuel to all " on this motor?-----What if a high speed jet was plugged in one carburetor bowl ?

No, one can never be absolutely sure that is not the case but in 40 years of operating my '74 115, I've never had a carburetor or a jet problem or any sort of fuel problem, really. If the fuel was dirty and plugged up a jet then one would expect all the jets to be plugged off or the engine to be very difficult to start and keep running. Yes, it's possible that may be the problem but in my experience it is nowhere near the most likely cause. Because I know the motor is getting fuel I wouldn't even look at the fuel side until I had ruled out that it's not a spark problem first. Until I was able to determine that I had spark on all 4 cylinders - even under load, I wouldn't start looking on the fuel side. Just playing the odds here based on personal experience.

There have been several instances over the last 40 years where that 115 of mine was only firing on 3 cylinders. In every single instance, it was a spark side problem. Generally a coil, a spark plug lead or a bad spark plug. The last time it happened it really fooled me because I quickly figured out which cylinder was not firing and then decided it was not the spark plug because there were no visible defects such as cracks in the insulation or problems with the electrodes. It looked to be in perfect condition so I put it back in and went further up the chain. After changing out just about every component further up the chain in the ignition system with no success did it finally dawn on me that I should have tried switching out the spark plug. D-ohh! Learned a good lesson there. ALWAYS check all of the simplest things first and make sure they are ruled out before looking at more complicated, lower probability things.

The thing is, I don't know how many hours this engine has on it, Despite being 40 years old, my engine doesn't have many hours on it so there are some types of problems that don't expect to occur with my engine just because they usually only happen when engines have a lot of hours on them and are near worn out. ADM1476's engine may have a lot more hours on it than mine so maybe some of my assumptions aren't valid. But I still maintain that something simple on the spark side is the most likely culprit and that because the engine is getting fuel, one shouldn't even be looking at the fuel side until the spark side has been thoroughly checked and can be definitively ruled out. Just my $0.02 worth.

 

[adm1476]

Good call Roj115. I will install new plugs first. I missed the part about the spark jumping 7/16 gap. I thought it was asking if it has 7/16 spark plugs. Which made no sense. LOL I have not done any spark tests other than to see if it did have spark on all 4 cyl. Checked with a plug out and cranking. They all sparked. No idea if they do under load. Realized carb was not pulling and went to work on that first thing. Never looked at or for a spark issue. My guess is that this motor has a decent amount of hours on it. Judging by the looks of it. I got it for 150$. I did a compression test at the guys house, it was good so I paid him loaded it and brought it home. Been playing ever since. I will give an update as soon as I get some time to work on it some more.