Need help diagnosing Evinrude 9.5 problem

[titantn]

I have a 1968 Evinrude 9.5 Sportwin. I bought it from the original owner and while he said it ran good, I knew it would need some kind of tune up. Well, it runs, but not what I would consider well. It has a stutter every few seconds, and won’t stay idling very long unless you add some choke.

So far I’ve: changed gear oil and impeller, carb kit, points, plugs, confirmed I’m getting spark to both cylinders, 75# compression on both cylinders.

I’ve had two "outboard" mechanics look at it and once they figure it’s not a simple tune up they’ve both said "you can only get so much out of these old outboards. Sometimes you just have to accept whatever they’ll give you." I’m not buying it. I know this could run like a sewing machine if I could find the problem.

The stuttering "seems" like it’s electrical. It happens very quickly and recovers very quickly. The poor idling "seems" more like a fuel issue. The motor will power up to full throttle with no problem and stay running fine in terms of fuel delivery, but the stutter is still there.

So, any suggestions as to how I can diagnose this? And one more thing, it runs the same with the cowl on or off. Thanks for your help.

[raglover]

A few things to check

1. Carb clean, assume soil yo installed a kit, but worth checking
2. Needles properly adjusted? About 3/4 turns out on low speed? Packing good?
3. Fuel tank and hose good? Vented?
4. Fuel pump good? Sometimes a bad pump will work ok until under load the can’t keep up. Can trouble shoot by pumping bulb to see if it goes away,

Not sure what companies should be on this motor, 75 seems low, but if even maybe ok. Could be gauge error too.

[david-bartlett]

Welcome,

If you are trying to run this in a barrel with no fresh air around then start over. These motors NEED clean air to run right.

The carbs on these are "different’ but still just a carb. Proper cleaning is essential. Points changed, but they still have to be nice and shiny. How are the condensers? Are the coils original and cracked at all.

Some people love these 9.5’s and others can’t throw them far enough. You will find out which one you are, but keep posting and it will get sorted out.

[fisherman6]

75# even compression is what I would consider very good for one of these. Many of them are high 60s to low 70s for compression. They are a low compression engine and it should run nicely with 75# on each cylinder.
-Ben

OldJohnnyRude on YouTube

[wiscoboater]

Condensers, plug wires/boots, fuel pump diaphragm, all good?

[crosbyman]

these old outboards run perfectly well …and my 9.5 is below 75 pounds compression …try a new mechanic and make sure you tell "the non believer" what you found when you get it going !!!

you have not mentioned coils…. are they new? …. if originals are still in with the smallest crack… they need to be changed but its your call as to swap in new ones …. careful with routing of coil wires around the cam a carb kit needs a "carb clean" to be effective….. real clean !!!.

adjust timing with a VOM if you do not have the famous FR tool

http://www.youtube.com/watch?v=ga1Cjymj … e=youtu.be
http://www.leeroysramblings.com/OMC_9.5.htm

Joining AOMCI has priviledges 🙂

[fleetwin]

OK, I want to get back to your original running complaints to make sure I understand exactly what is going on…
First, let me know how you are running the engine. In a barrel/test tank, or have you actually had it running on a boat? Like others have said, trying to run/tune/diagnose these engines while running in a tank will lead to false conclusions and added headaches.
I will proceed "assssuming" you have run the engine on a boat. Does the "stutter" occur at high speeds as well as low speeds? If so, is the stutter only a momentary (a few seconds) thing while running at high speeds? I’m asking this because I am trying to point you in the right direction, electrical/ignition faults are usually momentary that result in quick/sharp drops in RPM. Fuel faults are usually bogs or a smoother loss of RPM.
You mention replacing points/condensers. Did you run the engine before doing the ignition work? If so, did the running characteristics change before and after doing the ignition work? Who did the ignition work, you or the repair shop? This issue could be something as simple as a bad spark plug, even though the plugs are probably new…I would try another set of plugs before going much further, use Champion J6C plugs gapped at .030".
You mention that the engine won’t idle well, but slight choking helps keep the engine idling. You are correct, there might be more than one problem creating these issues. I guess I would attack the high speed problem first to see if that solution will solve the idling problem.
The key to success, and minimal frustration/expense is to never over look the simple stuff….Most problems are fairly simple, but we really confuse things and create our own problems when the basics are over looked and we dive into complex areas.
Is there any way you can post a video of the engine misbehaving at high and low speeds?

[titantn]

Wow. Thanks for all of the feedback. You guys are good. I’ll try to answer everything to help you help me.

It has been run in a barrel and on the lake. It runs the same in both locations. As I said, the stutter is extremely quick and at both slow and fast speeds. All of the items I mentioned in the first post have been replaced, but not the condensers, coil packs, or fuel pump. I really feel like the stutter is something electrical because it’s so quick, so I tend to rule out the fuel pump.

The coil packs visibly look good- no cracks that I can see, and I’m getting spark on both cylinders. I’m not sure if there’s a more definitive test you can do other than a visual check.

I am running the J6C plugs but I could get some new ones and try that again. All of the work was done by me, but I’ve taken it to 2 mechanics since then and they can’t/won’t figure it out. I’m very confident in the few things I’ve done including setting the timing of the points because I actually bought the tool from Frank – http://www.franksoutboardtools.com/timing-fixtures.html

Let me know what you think.

[fisherman6]

Have you replaced the spark plug wires or at least inspected the old ones for pinch points, wear marks, burn marks, places there may be electrical leakage, etc. Are the wires firmly seated in the coils and no corroded connections at the spikes? Maybe it is occasionally arcing to ground somewhere and doing it intermittently because of vibration?
-Ben

OldJohnnyRude on YouTube

[crosbyman]

coils may be cracked under did you pull them out and inspect closely …

if you can run the engine in total darkness to inspect / see for if any high voltage is jumping around

In any event if coils look original do yourself a favor get new ones and may as well change plug wires with solid core ones ( NOT THE CARBON FIBER ONES !!)

screw the wires on the coil pin slide the booth over ( Personaly…. I add a dash of silicone under the small wire booth )

careful careful with coil wires to the points screw tuck them well away from the cam lobe !!!

hard working … make money busy mechanics are to busy to work these oldies…. they prefer to swap parts and they don’t have any spare parts for oldies . Best to do your own and learn… that is the fun part of this hobby 🙂

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