1988 EL75 #1 cylinder not firing or firing intermittently

[Solarman]

What do you mean by "enough" fire?
The timing light can show you it is flashing just like the other cylinders, which means it fires the plugs as the other cylinders do. If it flashes, like the other cylinders, it is getting the same impulses to flash. Also, the same pulse coil operates all three cylinders.
The intensity of the spark is determined by the coil, plug wire, and plug. If questionable, swap all 3 with a different cylinder to see if that makes a difference.
The CDI (condenser discharge ignition) pack is the only other item between the impulses and firing of plugs.

So what tells you "enough" fire, or not "enough" fire?

Post back when able to let us know.

[johnstout]

Okay, I will continue on the fuel and air side of things. I have changed all the ignition coils around and no matter what I do the #1 cylinder is the one misfiring regardless of what coil I have on it.

I have a few more hours left for the cure on my gasket sealant to be done. I'm crossing my fingers. Will let you know how it turns out.

[Solarman]

If sure you have misfire, certain it is not firing like the other two cylinders, check neutral switch to be sure it is working properly, if it is not it could be dropping #1 cylinder for safe mode. Otherwise, it could be your CDI unit?

I was under the assumption all cylinders were firing equally.
It is not easy from this side of computer to visualize and diagnose.

I would be suggesting setting the air mixture screws at 1-3/4 to 2 turns open from lightly seated. Your manual's setting of 1-5/8 turns is not far from 1-3/4 or 2 turns.

Good luck, post back when able to let us know how it's going.

[johnstout]

Well, it appears that I had a gasket leak between the #1 carb and the intake manifold. After removing all the carbs and using the sealant there is a remarkable difference on how the motor runs. It still isn't real smooth but does not appear to be misfiring any more. I haven't been able to find any you tube videos on how this motor sounds running on ear muffs so I really don't have a good reference point to go buy. Like I indicated, I just bought this thing a couple of weeks ago.

Thanks for your patience with me. Been a long time since I messed with an outboard motor. Have had inboards for the last 38 years.

I now feel comfortable in taking it for a lake run to run some of the bugs out of it. I'll keep you posted.

[johnstout]

I took the boat out today and here are the results;
Idle out of gear is okay but still a little rough
Idle in gear is very rough and unless throttle is increased it will die
Acceleration is weak but smooth. Top rpm is 4000
If I trim the engine high then I get an alarm
The alarm continues until I throttle back to about 2000 rpm
This engine gage only indicates oil level and flow
I have no idea what the alarm is trying to warn me about
The biggest problem I am having trying to trouble shoot this engine is that the manuals online do not match what the configuration of my engine.

The manuals show a throttle sensor on the #2 carburetor. Mine has none
The manual talks about an electronic idle adjustment. Mine has none

The only place that I have been able to find any info on this EL75 is on Brownspoint.com. And the diagrams fit what I have to a tee. Its obvious that there is something unique about these EL models.

Is there a manual out there for this Model? Or, can someone guide me in the right direction?

[2014DF25ARS]

I had a 3-cylinder Evinrude that was missing on one cylinder and wouldn't idle properly. After doing a lot of what you've done, I found water in one of the cylinders and found that the head gasket was blown out around the cylinder, sucking water into that cylinder and screwing up ignition.

[Solarman]

I couldn't tell you what the EL difference is, compared to my DT's, but browns point may be able to get a manual for you're motor, or possibly do a google search for your manual. Something may show up.

Now that you have the gasket leak fixed, try adjusting all the idle air mixture screws to 1.5 turns out. Then try at 1.75 turns out (all carbs same setting). Then try at 2 turns out.

If the lower settings (1.5 turns) does better, then try going to 1.25 turns, then 1 turn?

Yes, 25ars, those things can happen.

Good luck, post back when able to let us know how it's going.

[johnstout]

You don't address the rpm issue or the rough running under load issue. 4000 top rpm sounds pretty low for this engine. Doesn't timing come into play here?

[Solarman]

Timing does play a major role, but timing is controlled by your sensor assy (under flywheel), the linkage from throttle assy, and CDI unit. You would need a manual for your motor to properly check these items. It is possible to check timing by using timing light on each plug, they should have some marks on flywheel, but i am not familiar enough with your EL series to give much help.

There is a linkage from throttle linkage to the timing base/sensor assy under flywheel? That linkage moves the timing base/sensor assy as the throttle moves. Again, you need a manual for the EL75 to check these areas.

I would focus on blockages of jets, pas-sages, carb settings, and gasket leaks, unless i was positively certain i had a spark problem. Your problem seems to be related to fuel and gasket leaks. You said you added sealant to one area, and running improved. Do you think new gaskets, and going through carbs again thoroughly might help? Did you clean the high speed jets, and adjust float settings with new needle valves?

When you raised motor, did rpms go over 6k? Is it possible you raised the motor too high, possibly causing limp mode to kick in?

Add i said, it is difficult from this side of computer to guage what is happening on your side of the computer. If it were me, I'd get new gaskets and re-do carbs, with (carb kits) needle valves, float settings, and make sure carb settings were right before messing with timing. This is because you had problems with gasket(s) and running did improve? And I'd add some fuel additive to fuel until everything was good again.

Good luck, post back when able to let us know how it's going.

[johnstout]

Okay Solarman, I have removed and cleaned and sealed and installed carburetors 4 times since we last communicated. Minor improvements in engine operation but the number one cylinder still is not firing properly. If I turn the air screw in or out on #2 and #3 carburetors the engine responds accordingly. When I turn the air screw in or out on the #1 carburetor very little change in engine operation. I have swapped adjuster screws around between carburetors and no matter which adjuster screw is in the top carburetor the adjustment makes no to very little difference.

Can I flop carburetors around to see if things change so that I can definitely narrow this down to carburetor or something else. I know I have spark at the #1 cylinder and I have changed ignition coils around with no change. Installed new spark plugs, new spark plug boots and connectors.

[Solarman]

Ok, what are the compression readings on each cylinder?

And you said you checked the reed valves on the #1 cylinder.

Psst back when able.

[johnstout]

Yes I did examine the reed valves and can see nothing obvious. They all appear to be in good shape.

#1 cylinder 55 psi
#2 cylinder 65 psi
#3 cylinder 75 psi

[Solarman]

That could be the reason you're having issues. Your compression is too low. To start with, #3 cylinder should be (ball park) 85-95 psi. The other 2 cylinders should be within 10% of the strongest cylinder.

You could have a bad head gasket, or your piston rings /cylinders are worn down.

Good luck. Let us know what you plan to do.

[johnstout]

I took the head off today and I don't see an obvious path of leakage. However, the gasket is in the worst shape of any head gasket that I have ever seen. It is seriously deteriorated around the water channels and basically just crumbles apart in most areas.

I don't see any rusting or scoring on the cylinder walls, the pistons are not sloppy and do not have much carbon deposits on the tops.

This is an odd thing that I did notice. On the inside of the head the bottom cylinder area has a light carbon deposit all the way around. The middle cylinder only has a light carbon deposit for about half of the surface on the exhaust side and the top cylinder only has a carbon deposit for about a fourth of the surface area on the exhaust side.

Your thoughts?

[Solarman]

Probably caused by lower compression, causing poor combustion in each of the cylinders. Possibly a new head gasket could bring compression back up in all cylinders? No guarantees, but worth the trial.

Good luck, post back when able to let us know what you're doing.