I have a 1989 Evenrude 25hp. It has always ran great and started great. last fall it started to act up a bit and not running at full tilt. This spring, I only have one cyl firing. I put in new plugs, compression is good on both, I have spark in both, and gas in both. the bottom cyl fires. the top cyl, will not fire and plug comes out wet, so it too is getting gas.

I have taken off the carb and cleaned it well. Tested bot coils and both are working.... Very purplexed at this point. I got spark, gas and compression... what else am I missing?

Try to see if you can switch the coils for both cylinders. If the problem is reversed on the firing cylinder you have a bad coil.

Make sure you have sufficient air supply also. Spark, fuel and compression are fine, but the most overlooked is the air supply.

Try swapping coils as Valv talked about above... at least it would rule the coil out.

marine_man

Thanks fellas, I did change the coils and even took the top coil to a shop and had it tested. It was fine.. ???? Must be something with the air then... ??? the reed valves looked fine when I had the carb off but hummmmmmm .. Not sure what else to do. It has to be something simple I would think.. Might have to break down and take it in to a shop.. I just hate to toss out that much $$$$ for shop fees when it might be a minor fix.

disclaimer: I am not a mechanic. That said one thing came to me when I read this..... sounds like a change-up when you are expecting a fastball. Doesn't matter if everything is right.... if it happens at the WRONG TIME. Any chance that is what is happening???

Sorry Rusty.. I'm at a loss then if you've cleaned the carbs and have checked the ignition source...

You didn't by chance mix up the coil & plug wires, did you and connect the wrong coil wire to the wrong coil?

marine_man

I would put a timing light on it while running to check for spark. Sometimes you can have spark with the plugs out and no spark under compression.
Lets back up a second also.
You said the suspected cylinder had a wet plug, correct?
could it be water? Water will bead up and is quite distinguishable when it is on a plug. After running it a bit, take the plug out and tap it into your palm. They water will be in a bead.
Just something I thought I'd throw in there.

Another issue we haven't verified is compression. Do you have good compression on the faulty cylinder ?

What about the stator?

Have a 1979 that had a bad one. I don't think that would affect just one cylinder/coil though?

I believe OMC had some issues with stators going bad and not being designed the best with the inner plate of the fly wheel in certain years.

Always start simple re-check everything 4 times and see if it isn't something you could have missed. Many problems can be because of bad gas. Do you use fresh non-oxy fuel? When the coils were checked did they register the same or was the one a bit weaker than the other? Not to ask a dumb question but are the plugs new? I would guess the wet plug is not firing strong enough to ignite the fuel/air mixture when in the cylinder and spinning at a higher rpm. Not firing points to an ignition problem IMO. Does it run the same with the bad cylinder unplugged from the spark plug or is there a difference?

I've told my 14 year old who enjoys working on stuff that most problems are operator error when he's had problems with something. Sure is funny till he uses the saying on me when I'm having a bad day working on something.

Good luck with it.

Well we worked on the darn thing for about 4 hours again the other night.
We checked compression, over 100 on each and both the same. Checked for water, nope.. Its all gas.
Checked both coils and all is set up right.
Changed plugs again and nothing.
Sparks like crazy with both plugs out, most of the time if it will not spark under compression it is the plug and not the coil???
Checked all the reeds behind the carb and they are all free.

We are really at a loss for ideas...

Some one said maybe something under the flywheel is not adjusted right and not letting the top coil spark at the right time.. Perhaps a celinoid or something under there...???

Plus now we noticed that when running it, the gas drains out of the squeeze ball. We have to keep pumping it up when it starts to sputter because it is not keeping the ball tight.. ??? sigh sigh... I tell ya what.... that little black cloud had better move on soon.......

I am going to take off the flywheel and see what is under there next.

I'd check the fuel pump then. If the diaphram has a hole in it, You can actually pump gas directly into the crank case, that and it wont supply the carb with gas. That would explain both symptoms-wet plug and squeezing the bulb. Also, did you verify spark while running with a timing light?

Think you just found your problem a fuel leak some where.

Agree with boatfixer about the fuel pump. Cheap and easy to do. Never a bad idea to put a new one in if it's been a while. Ethanol can eat those and hoses like candy if the fuel has sat in it. On all the small engines I run I only use non oxy fuel and run them out of gas when they are going to sit for some time.

If you've got,

1.good spark
2.good compression in both cylinders

and are having to pump the bulb it is because of more than likely a leak some where in the fuel system. Check hoses for cracks, make sure all hose clamps are tight. Might not be a bad idea to put new hoses on if they are old. Fuel lines are a pain but once they are solved the motor will most times run like new.