Evinrude 25 rough running, missing? help is appreciated

Hi, new member here. I have a 1989 Evinrude 25 long shaft with remote controls. The engine starts relatively easily when cold, and runs fine. It seems when it warms up I have problems. If I accelerate gradually, it runs erratically and vibrates and sounds like it's running on one cylinder. Obviously performance suffers. Then, if I give it full throttle, it has great acceleration and it runs smoothly. I'm thinking it's ignition related, but I don't have the special test equipment the manual calls for to test the electronic components. The motor has great compression. I rebuilt the motor with new rings and an oem gasket kit. The carb was cleaned and rebuilt with an oem kit as well. The plugs look like new and the plug wires are new. I installed a new water pump and thermostat, so I don't think overheating is an issue. I only use ethanol-free fuel. I've heard the power pack is a common problem. Does my issue sound like that? I am considering replacing all of the ignition components with new, but that may be silly. If anyone has anything else I can check, please post. I appreciate any help.

Marty

Check that the armature plate doesn't wobble as follows:

(Magneto Armature Plate)
(J. Reeves)

If the armature plate has a a loose fitting, wobbling motion (the plate that the points, coils etc are attached to), it is usually caused by a slightly worn support ring. This allows the point setting to change erratically as the armature plate turns.

The cure is to remove the armature plate so that the support which is attached to the powerhead with 4 screws is visible. Then, with a screwdriver and hammer, or some tool of your choosing, and looking straight down at the support ring, make a slight indentation at what would be called the 12, 3, 6, and 9 O'clock positions. Install the armature plate and check for a smooth turning wobble free movement.

You may need to do that procedure a few times to obtain the proper fit (not too tight, not too loose), but it's worth the effort.
Use a small amount of anti corrosive grease between the aluminum ring and the brass support plate and also on the brass bushing of the armature plate when all is well.
Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:


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Make sure the points are set properly:

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.
NOTE 2: Should the cam have the word TOP
embossed on the top of it, that is a cam that could be installed upside down and this is simply telling you which side is up. It is not a position where one would set the points.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

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Double check the carburetor Idle Mixture Setting:


(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:


http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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Also... Make sure that the throttle butterfly just starts to open when the scribe mark on the cam is dead center with the center of the carburetor throttle roller.

Thanks for the great tips, but my motor doesn't have points.

nohasslekindaguy said:

Thanks for the great tips, but my motor doesn't have points.

Click to expand...

Yeah, sorry about that. The info I listed (copy/paste from my database) was designated for a different magneto equipped 25hp. I'll blame it on a senior moment.

However, assuming that you have great compression, remove the spark plugs and rig a spark tester whereas you can set a 7/16" gap for the spark to jump. THe spark should jump that gap with a strong blue lightning like flame...a real SNAP! Does it?

Check the spark thru the full range... retarded to full spark advance. If the spark remains the same, it's a pretty safe bet that the ignition is okay.

The synchronization could set up the problem you describe... check to see if the throttle butterfly just starts to open when the scribe mark on the cam is dead center with the throttle cam roller.

Also, that cam roller should be approximately 3/8" in diameter... some of the rollers consist of two pieces, a black roller with a clear sleeve covering it. The clear sleeve has been known (frequently) to break away leaving the inner smaller black portion serving to operate the butterfly... too small, out of sync! Something worth checkiing.

Thanks again. I am getting a spark tester so I can check it out. I did sync the timing, but my roller sounds like it may have fallen apart as you describe. There is no clear part on the outside. I appreciate the help.

nohasslekindaguy said:

Thanks again. I am getting a spark tester so I can check it out. I did sync the timing, but my roller sounds like it may have fallen apart as you describe. There is no clear part on the outside. I appreciate the help.

Click to expand...

I should have clarified my statement about the roller..... The older rollers are one piece (3/8" Dia) and have no clear outer sleeve..... The newer rollers are usually two piece rollers that have that outer sleeve.

In either case, the roller should be approximately 3/8" pertaining to its outside diameter.

I ordered a new roller since it had flat spots worn into it anyway. I think I figured out the problem. I started doing some of the ignition tests shown in the manual. I did the one where you make timing marks for each cylinder, then check each cylinder with a timing light. I found a misfiring problem. I sometimes see marks for both cylinders when checking cylinder #1. When both marks show up, you can hear it run rough. I guess that probably means an ignition module problem, but I haven't tested everything yet. Should I stay with OEM parts, or is the CDI conversion kit a good idea? Thanks again.

kimcrwbr1 said:

I`m thinking you say it runs good at slow and fast but have problems intermediate speeds it could be wiring issues also. Clean all the connectors good with electrical cleaner and put together with dielectric grease. Bend the wires looking for weak spots and sand the grounds metal to metal. Fix any bare,cracked or broken wires sometimes wire get corroded under the insulation you cant see and at certain timing positions you will get erratic spark. Also check the trigger base does not wiggle up and down and moves nice and smooth it could be a air gap issue with the magnets. For sure get the follower roller working good and sync it properly. We also like to see compression numbers real good compression is not an acceptable answer same with good spark is not the same as 7/16 gap with a spark gap tester brite blue snap.

Click to expand...

Thanks for the help. Actually, it doesn't run that well at slow speeds, either. The problem just gets worse as it warms up. Yes, I will check all of the wiring for breaks or corrosion, just didn't have time today. The trigger base is smooth with no play. I checked compression today and both cylinders were exactly 124 psi. Shouldn't be a problem there. I'm getting a spark tester to make sure everything is fine there. I will track down the problem, at least I'm on the right track. It's definitely electrical. Thanks for the advice on the cdi conversion.