1964 Evinrude 9.5 Misfire

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Lagrue
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1964 Evinrude 9.5 Misfire

Postby Lagrue » Fri May 11, 2018 2:17 pm

My 1964 Evinrude 9.5 (short shaft) is giving me a misfire.

I reworked this motor last summer - New waterpump and lower seals, new spark plug wires and boots, rebuilt carb, new fuel filter and lines as well as brand new tank. Pulled the points and filed them flat and shiny (clean) as well as set to .020". New J4C plugs. Coils tested good.

Had a few problems with the motor while fishing last summer and then finally got it running nicely. Took it duck hunting during winter and promptly sheared the flywheel key. I replaced the key on that trip, spent a few mins tuning the low speed idle (no high speed on these) and she ran great all winter.

I pulled it back out this week to get it set for some fishing this weekend and it ran poorly. Consistent coughing every 3-5 seconds at idle, did not want to go into gear without coughing heavily.

Last night I went ahead and pulled the carb and cleaned it well of any varnish or dirt (nothing in the jets), checked the float set. I tested the coils and both test at 3.6ohms. went ahead and cleaned the points again and re-set them to .020". Results when running it were/are the same - Except!

I tilted the motor up to level (its mounted to the back of my boat deep in a barrel, so was tilted down) and instantly the idle smoothed out and it ran like a clock? I tilted it back down and it immediately went back to running rough. Tilt it back up to vertical/carb horizontal and the engine runs like a top.

What is going on here? I'm truly at a loss. The one thing I've not opened up on this (beside the crankcase) is the welch plug on the side of the carb. I have not ordered a rebuild kit that comes with it, so I've not opened up that side to see what is inside that area. Is it possible something is stuck in there, and gravity is pulling it down into the way causing my cough? I figured the engine was only running on the low speed needle while idling.

One thought is that the float is a cork original. Is it possible that the float is sinking, the gas level is too high and swamping the low end needle intake?

FrankR
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Re: 1964 Evinrude 9.5 Misfire

Postby FrankR » Fri May 11, 2018 4:23 pm

Get it out of that barrel and on a boat on the lake. It more than likely is inhaling it's own smoke when you tilt it down into the barrel. Stick your head down in there and you won't be able to breathe either.

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Lagrue
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Re: 1964 Evinrude 9.5 Misfire

Postby Lagrue » Fri May 11, 2018 4:59 pm

Thanks much for the feedback Frank.

I'm definitely aware of the turtlemotor's tendency to breathe their own exhaust. The exhaust bellows on this motor are in good shape.

To your point, this one was running in a barrel with its cover off. I do also have a couple extra breathing holes under the handle in the cover to get more clean air in when the cover is on. Will try your suggestion and run it Sunday on the lake and see how it goes.

I did just run it again a moment ago. It runs great in the barrel when essentially level (highest setting on the tilt adjustment), but coughs pretty badly when on its lowest tilt setting in the same barrel 20 seconds later, nothing but the tilt setting changed....

outbdnut2
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Re: 1964 Evinrude 9.5 Misfire

Postby outbdnut2 » Fri May 11, 2018 6:13 pm

In addition to the bellows on the shift rod, the large rubber boot between the housings near the bottom can cause them to eat their exhaust when in the barrel or until up on plane. This also happens if the outer housing is slightly deformed so it doesn't seal around that boot. You can't see the boot without taking it apart.
Dave

At this link, it's part number 87:

http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1969&hp=9.5&model=9R69S&manufacturer=Johnson&section=Lower+Unit+Group

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Lagrue
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Re: 1964 Evinrude 9.5 Misfire

Postby Lagrue » Sun May 13, 2018 10:48 pm

I ran the motor today at the lake.

With the motor in the lowest trim setting (as if to put a boat on plane), it would barely run. Just sputtered and popped. Would not stay running long enough to get it in gear, and if I did, it did not have enough power to push the boat.

Put the motor on its highest trim setting and it purred like a kitten. Ran and started great that way, so we just ran around the lake and fished with the nose up. This was a no wake lake, so it really did not matter. In either setting, the lower unit was very low in the water due to the low transom on this boat.

I put the motor in a can this afternoon and shot a quick vid. I tilted the can to be able to get a similar angle to the transom. It behaved just like on the boat. Check the vid out. Breathing its own exhaust has no effect.

I do have a carb rebuild kit on the way. Only things I can think of now are a sinking float or something to do with the low speed needle and its seals. Both will be replaced soon.

https://www.youtube.com/watch?v=GVqiH6oJ4II

david bartlett
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Re: 1964 Evinrude 9.5 Misfire

Postby david bartlett » Sun May 13, 2018 11:28 pm

I would look at the carb float. The cork may be loose on the mounting piece, or could just need proper adjustment of float.
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Garry in Tampa
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Re: 1964 Evinrude 9.5 Misfire

Postby Garry in Tampa » Mon May 14, 2018 2:33 pm

As you found out, that carburetor is sensitive to the tilt of the motor. Tilting it back (down) has the effect of raising the fuel level in the float bowl. . .
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fleetwin
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Re: 1964 Evinrude 9.5 Misfire

Postby fleetwin » Tue May 15, 2018 12:59 pm

Listened to the video, kinda sounds like it has a bit of an ignition miss to me...Not really loading up so much as misfiring...Maybe it is losing/weak spark on one cylinder that is more pronounced at the lower RPM trimmed all the way in....Doesn't sound great at the higher trim angle either, although much better than tucked all the way in.
I guess I would start with new plugs, even though the ones you have might be new, doesn't mean they are any good. Then, I would use either the inline neon testers or a timing light and run the engine when the sun goes down...Perhaps you will see one cylinder losing or with weak spark...

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Lagrue
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Re: 1964 Evinrude 9.5 Misfire

Postby Lagrue » Sun May 20, 2018 12:09 pm

I finally fixed this issue and wanted to wrap this up. I must admit I feel pretty silly now that I know the answer.

First off, I did purchase a carb rebuild kit and rebuilt the carb (as opposed to the thorough cleaning I had given it previously). I do get a more firm bulb on the fuel line now, so I think the new float in the kit was more than worth it.

Running it with the rebuilt carb was exactly the same, so that narrowed it down to ignition issues as suggested above.

At this point, I elected to put in new points and condensors and check that everything is exactly as it should be. I had previously filed/cleaned the points and reset them. I also pulled the coils and tested them separate from the engine as I was doing the ignition overhaul and they were fine again.

Again, no joy. Same sputtery engine. At this point, I'm at a loss, but I think the only part I've not looked at was the wiring for the kill switch. I disconnected it, fired up the engine and its running beautifully...… AHA!

I removed the switch from the motor and took it in to the workbench. It had a rattle inside. I pulled off the rubber cover and the copper cone contact inside had broken free from the rubber part. It was effectively bouncing around inside the killswitch and periodically killing the motor for a tenth of a second here and there. Tilting the motor backwards made the cone fall backwards against the contacts and kill the motor worse. The motor would buck and the cone would jump off the contacts and she'd start running again. Lather, rinse, repeat, backfire!

To fix the issue, I drilled out the broken steel OMC rivet and put in a new aluminum rivet with the head protruding so it would grab in the recess in the rubber boot. Polished everything back up, pressed everything back together and a continuity check showed it worked well. Shake it hard and the cone is firmly mounted.

With the switch re-mounted in the motor, it runs beautifully, either position, full down trim, or full up trim. Idle is very clean (much cleaner than in the videos. It goes into gear at a very low idle speed and I believe would troll my boat along at a very low speed quite nicely.

Maybe someone will find this thread in a search and it will help them.

david bartlett
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Re: 1964 Evinrude 9.5 Misfire

Postby david bartlett » Sun May 20, 2018 12:55 pm

Great job figuring that out. And you got to make sure the rest is in good shape in the process. Well done!
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