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1992 Evinrude 140 hp v4 looper cutting out.

C

Con

Member
Spark is good. Redone carbs. Redone fuel pump. Put seafoam through engine. 95 Psi on all 4 cylinders. Head gaskets might not be 100m%. This will be the 4th time I took the boat out since buying it second hand. The first 5 minutes is faultless but then it will start sputtering at high revs after that. It happened on the first 3 outings but today it was worse. It is as if the engine just cut out. I did not test the power pack or coils yet. I have put a video on youtube. I like working on my own stuff but it looks like I might need professional help. Any ideas will be greatly appreciated.

Youtube video: https://www.youtube.com/watch?v=i0AgHKtqc6k
 
The mention of "Spark Is Good" doesn't explain "How Good"!... The spark, with "all" spark plugs removed must jump a Air Gap of 7/16" inch with a strong wide blue lightning like flame... a real SNAP! Does it?

The cylinder numbers when standing in back of the engine, facing the spark plugs are as follows:

2....1
4....3

What are the actual psi compression readings of each individual cylinder? Your mention of questionable head gaskets raises a question in that area, but it's a specific that needs to be known regardless.

Air gap spark testers can be purchased at any automotive parts store... or you can easily build the following.

********************
(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

This can obviously be modified to a 6 or 8 cylinder setup tester.

********************
 
Thanks for reply Klink.
Yes I do and I had a thermo gun on the heads while it was idling on muffs. I know it is not a heat issue. Looked at the temps on the lake as well. As a matter of fact the engine was much colder than always but then it is winter.
 
Thanks joereeves.
I have made a spark tester and they did jump the 7/16 gap but it was a white spark. I will do it again and make a short youtube video so you can have a look. Maybe I'm missing something. The psi on each cylinder is 93 exactly on all 4. That's what doesn't make sense to me. I took off the heads and cleaned them + the cylinder heads but used old gaskets again.
 
The spark I saw was blue and hot BUT apparently the engine was running (guessing at least 650 rpm or so).

Yes, the spark test is to have all plugs removed and do the test at cranking speed. If the spark at cranking speed is identical to what I witnessed (running), I'll take your word for it.

NOTE: Regardless of what readings you may receive, or how the spark performs.... assuming you have a 6amp or a 9amp stator under the flywheel.... Inside that sealed stator unit, there is a large black coil at the front and rear portion of it that provides power/voltage (approx 300ac) to the powerpack capacitor in order to energize the pack.

Should the stator be cracked, even slightly, and have a sticky looking substance dripping down on the timer-base and powerhead, that would result in a voltage drop to the pack... and in turn result in erratic, weak, and eventually no spark. In situations like this, the stator may work perfectly when cold BUT as it heats up (and it gets damn HOT), the ignition will falter.

This stator mention may not be your problem, but it's something you do not want to overlook.
 
That's the only place I did not check because of taking off the flywheel and the price of a new stator. Guess I'm off to get the socket that fits over that big nut. I will post some photos from whats under there. The engine is running fine when cold, yes. I will do another spark test with plugs removed. I think you might be right. Cheers joereeves.
 
Did another spark test with all plugs removed and cranking engine. The stator looks different than on the parts list? Didnt see any cracks but there is a bubble on the surface. Could not load photos to this site, too big.
 
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Con said:
Did another spark test with all plugs removed and cranking engine. The stator looks different than on the parts list? Didnt see any cracks but there is a bubble on the surface. Could not load photos to this site, too big.
Click to expand...

A different ampere stator perhaps....

A bubble can exist on a stator directly from the factory, doesn't mean much, but worth keeping a eye on....

Graphic work: I use the program "ACDSee" for graphic work. Look into it. Very easy to use, reasonably priced, does it all!
 
You wouldn't say there is something wrong with this outboard. Cleaned it a bit and rerouted some wires from the stator. Took off the temp wire that ran over the spark plug leads to to the gauge. Question: The battery terminals were a little loose. Could move them from side to side . Could that also lead to cutting out of the engine. Butterflies on there (will replace them with nuts). I have decided to give it a rest for now and first repaint the boat. I will deal with this whenever I finish. I think I will replace the pack first when the problem is not solved. Thanks everyone for the help!

https://youtu.be/spvL0WyZ8y8
 
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con said:
you wouldn't say there is something wrong with this outboard. Cleaned it a bit and rerouted some wires from the stator. Took off the temp wire that ran over the spark plug leads to to the gauge. Question: The battery terminals were a little loose. Could move them from side to side . Could that also lead to cutting out of the engine. Butterflies on there (will replace them with nuts). I have decided to give it a rest for now and first repaint the boat. I will deal with this whenever i finish. I think i will replace the pack first when the problem is not solved. Thanks everyone for the help!

https://youtu.be/spvl0wyz8y8
Click to expand...


update: It was the power pack after all. Installed a new one and outboard is as good as new.
 
Update: it was the powerpack after all. Installed a new one and outboard is as good as new. Thanks everyone!
 
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