1974 Evinrude 15hp Misfire

[rotor_av8]

Hello, I'm back to iboats. I recently acquired a 15hp Evinrude that is on a 14' aluminum boat that we all love so much. I looked up the serial and discovered it is a 1974. The guy I bought it from said it runs great but was getting hard to start. I took it to the lake to check it out. I noticed if I didn't choke it much I could start it on 3-6 pulls, sometimes 10. Throughout the day I had it flood here or there during start up. The primer would tighten up nice and stay tight between fishing spots. Once flooded Id have to pull plugs and give it several pulls. When it ran it ran great, just not at low RPM or idle. I had to manually tend the idle because the idle screw (not air screw) on the side is broken.

I decided to put a carburetor rebuild kit in and did so. I found only silicone sealant (no gasket) sealing the carb to the engine thinking this was the big issue. I found the low speed needle seat chewed up. I wondered abut the reeds so removed the power head to my bench so I could remove the intake. I replaced the metal reeds with 2 stage Boysen reeds, surfaces all very well prepped for new gaskets. I rebuilt the carburetor replacing everything in the kit including the float upgrade from cork to plastic. I set the float to level. The carb interior was very clean, all passages were re-cleaned with carb cleaner and air blasting. New needle and seat, new low speed air screw seat and seal.

I put it all back together and started it up. The primer tightens up as it did before. It seemed to run really well and idle really well and have low end torque. I could shift from neutral to forward and reverse without the engine dying. EXCEPT it has an intermittent misfire. Occasionally it will do a weird pop, sorta seems like its loading up or out of time when it pops. One thing is it has a .060 main jet when I hear it should have a .054. Also the brass tube under the main jet usually has a slot almost like for a screwdriver, well someone tried to remove it marring it up, but it is totally open and clear otherwise.

I searched a lot of posts on iboats to try to solve my issues. I found this post from 2006 in quotes as follows:

"Hello All:
My mechanic informed me that my 74 Evinrude 15 had a recall on it after it came (he said this was one of the first years for this engine) out for a failing bearing in the stator plate and a head design that tended to overheat. ( can anyone confirm this?) He showed me the horizontal play in the stator plate of my unit and said it caused
the points to touch at times to cause a misfire. Said Evinrude came out with a kit that included a new head, stator plate and bearing for this unit to remedy the problem back then but the upgrade was never done on this unit and to find these parts is almost impossible now. Offered me $50.00 for junk/parts. Is he speaking the truth? Thank You!
Michael Tags: None

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Sounds to me like you've got a decent mech.The service bulletin is B-1425,dated 7/1/76.It refers to a fix kit,#389813.Last available 2003 at a cost of $235.22.

It is doubtful,but some dealer may have it sitting on a shelf,or maybe have a blown engine that has had the upgrade.

DHP"




So my questions are these:
1) If I indeed have this stator horizontal wobble does anyone convert these to solid state ignition to keep the points from contacting at the wrong time? I know its common to convert Briggs and Stratton to solid state and eliminate the points.
2) Should I switch back to a different jet? Do you think it may be sucking too much fuel causing it to load up and misfire intermittently? Do you think this is also the reason it floods on starting, getting too much fuel through the main jet?

Thank you guys so much for any and all help/suggestions/opinions.

Keep the spinning side down (opposite of helicopters where we say keep the spinning side up LOL)

rotor_AV8

 

[flyingscott]

You could have a lean sneeze because of the damaged low speed seat. Converting it to cdi Is straight forward you can use the evinrude set-up from 1977 and later models. You will need the stator assembly with pick-up,flywheel and coils. If you put boyesen reeds in you need to set the idle adjustment richer than stock as a lean sneeze can damage them

 

[rotor_av8]

It seems to be running fairly rich. I set low speed air screw at 1 1/2 out then little more rich. If I go richer it dies. It also seems to be smoking a LOT more than when I rebuilt it.

 

[flyingscott]

1 1/2 turns should run fine. What did you set the float at.

 

[rotor_av8]

I set it to "level or even with the carb body upside down". There is good room to open and good room past where the needle seats. The primer firms up good and stays firm. I just adjusted the points, filed them, used electronic cleaner to degrease everything but the oil soaked fabric. What oil for that that rubs the timing cam? Turbine oil ok? I use it for a lot of things. It seems to be running a lot better. Headed out for a lake test and I'll let you all know the result.

 

[OptsyEagle]

Not sure if horizontal wobble is the same thing as lateral play but I suspect it is. Joe Reeves had a fix for this. Worth a try if the alternative is to turn the motor into a parts motor.

To fix the wobble do the following:

Armature plate is held onto the retainer (below armature plate bearing and support ring) by 5 phillips head screws. Loosen all of 'em and pull their threads up into the armature plate itself, which un-hooks it from the retainer. Lift the armature plate off the 'boss' at it's center (boss is on top of powerhead w/crankshaft going through it). Now, pull that plastic armature plate bearing off of it's holder (support ring) and set it aside. Place the armature plate back onto the 'boss' and check lateral play.. turn a bit and check again. If it moves laterally, what you do next will take up the slack space. Again remove armature plate and look at the 'boss' on top of powerhead. It's round, and the bearing surface is about 1/4" in height. Take a sharp centerpunch (or a screw, nail, etc) and 'peen' 4 spots halfway up the height of the sides of the boss at the 12, 3, 6, and 9 o'clock positions. What you're doing is making a little 'wave' of metal rise up around your punch marks, and that metal will take up the slack space between the 'boss' and your armature plate's center bearing surface. Start w/small 'peens', replace armature plate and check play (also, turn the armature plate to check for too much binding). If it still has play, peen the same exact spots again, and re-check play until there's no play left. Don't peen so much as to make the armature plate bind too much when turning(creates stiff throttle).. a little resistance is fine.

Now, reassemble. *The plastic armature plate bearing ring is dry fitted.. wipe all grease/oil off of that bearing, it's support ring, and the underside of the armature plate where it rides before reassembling*. Also, you can use needle nose pliers to pinch the bearing ends together for reassembly.

The 'boss' isn't a dry fit. I use white lithium grease on the boss (sparingly).

Set points to .020". Make sure they're filed-up clean and shiny (I remove the pointsets, disassemble, place each point 'face' aiming up in a vice, and use a file to gently remove pits/dirt. I then use a dull file to make the faces shiny-new, then a points file to slightly bevel the edges before reassembly). Move the throttle and check the points again to make sure all the play is gone and your points maintain their gap.

Now, you'll have no more lateral play in your armature plate, and your timing will not jump around w/changing point gap that it caused.

Also, make sure you are using NGK spark plugs B6HS, and not the specified Champion plugs. That model of motor does not like those champions. Most people here have confirmed that the NGK tend to work better and last longer on that model of motor (1974-1976 9.9/15Hp).

 

[rotor_av8]

Lake test result: seemed to run well at first. Later it began to load up and run crappy on the low end. I'm not sure if this is the bad condensors I've read about on ramblings page when they heat up or wrong plugs or timing wobble. I've noticed if it cools down for 10-15 minutes it needs choke to start. I tried low speed and it just misses and runs bad, maybe even on 1 cylinder. I'm headed to buy the NGK B6HS plugs today and do another test and put fresh start over fuel in it just to be sure. That is good info optsyeagle, I'll try that if this doesn't work. My other option is a new carburetor or different jet because mine has that brass tube under the main jet slightly damaged like someone tried to remove it with a screwdriver since it has a slot cut into it. Does anyone have a good carb body? How about a .054 jet? I've seen new carbs for $150-200 but that's what I paid for the engine, $200. Guess I got what I paid for. I'll update after this lake test today.

 

[flyingscott]

Lake test result: seemed to run well at first. Later it began to load up and run crappy on the low end. I'm not sure if this is the bad condensors I've read about on ramblings page when they heat up or wrong plugs or timing wobble. I've noticed if it cools down for 10-15 minutes it needs choke to start. I tried low speed and it just misses and runs bad, maybe even on 1 cylinder. I'm headed to buy the NGK B6HS plugs today and do another test and put fresh start over fuel in it just to be sure. That is good info optsyeagle, I'll try that if this doesn't work. My other option is a new carburetor or different jet because mine has that brass tube under the main jet slightly damaged like someone tried to remove it with a screwdriver since it has a slot cut into it. Does anyone have a good carb body? How about a .054 jet? I've seen new carbs for $150-200 but that's what I paid for the engine, $200. Guess I got what I paid for. I'll update after this lake test today.

Replace the points and condensers with FACTORY parts not aftermarket put . Because of the ignition on that the aftermarket parts do not hold up on them.

 

[rotor_av8]

Missed updating this. It ran great and idled great with the new plugs with an occasional sputter. Plugs fouled pretty quick. Has new gas and oil mixed at 50:1. Oil from a marine boat dealer so should be good. With newer oil can I lean out the oil ratio? Has anyone done the CDI ignition to get rid of the points?

 

[rotor_av8]

Does anyone have jets for sale?

 

[flyingscott]

That motor is HARD on points and condensers. I have had several of those motors never run NGK plugs and always put factory points and condensers in them. First thing I would do is replace the points and condensers. That ignition is specific to that motor it works well but requires more maintenance. It's not like the 73 and earlier magnetos. I have made the CDI conversion but you almost need a parts motor because of the little parts in the stator. I doubt you have stator wobble the classic symptom of that was the motor would mis-fire hard enough to shut the motor down. No I would not recommend running that on anything but 50-1 my 89 model runs 50-1. They are good running motors when dialed in.