83 50 HP Johnson Not Running 100%

[Bosunsmate]

I ripped the reed valve off and it was fairly open, seems the lack of back pressure towards the carb was making it run too Rich and was flooding the one cylinder over time as making it just not fire.

As far as pictures go, maybe you can make something out of these and lead us down the right path

(This is with the throttle lever DOWN)

Lack of backpressure can be caused by a worn crankcase seal or crankshaft seal.
Those photos arent showing

 

[Bosunsmate]

Remember that those reeds a only for idle and they are generally not affective for higher operating speeds as they stay open as the higher need for oxygen/fuel keeps that mix flowing into the crankcase with minimal chance of backfiring backwards (well thats what ive being told more than once)

 

[racerone]

Reeds are opening and closing at idle and also at full throttle.--------If not there would be NO CRANKCASE COMPRESSION !!!!----Please review the way one of these engines operates !

 

[jakedaawg]

What I meant in post three was new plugs and then the stuff in post two.

Stop, Step Back, Take a deep breath....

Now:

1. Compression test. Post results

2. Open air gap spark check set at 7/16", post results.

3. Fuel sample into a clear jar, post results.

4. With motor just barely tilted (just enough to get a downhill slant on the carb throat) and with air silencer removed, squeeze bulb with arrow pointing up till firm.
Gently continue squeezing the bulb. If bulb continues to depress search for the fuel leaking. Its probably coming from one of the carb throats. Report results.

 

[robstead]

What I meant in post three was new plugs and then the stuff in post two.

Stop, Step Back, Take a deep breath....

Now:

1. Compression test. Post results

2. Open air gap spark check set at 7/16", post results.

3. Fuel sample into a clear jar, post results.

4. With motor just barely tilted (just enough to get a downhill slant on the carb throat) and with air silencer removed, squeeze bulb with arrow pointing up till firm.
Gently continue squeezing the bulb. If bulb continues to depress search for the fuel leaking. Its probably coming from one of the carb throats. Report results.

Disregarded everything on the motor in the past and did the basics.

Compression: 120psi on both cylinders
Spark: Spark clears 7/16" gap, but was still curious and hooked up my spark tester and the light in the tester flickers on both coils, even with brand new plugs.
Fuel: Everything checks out great within that, no leaks and fuel looks great.

My main concern is the intermittent spark occurring, its obviously enough spark for the motor to run but this is the cause of the rough running?

Going to head over to CDI trouble shoot and double check everything, but is it almost safe to say the power pack is going?

 

[Bosunsmate]

How do you know its intermittent spark and not a fuel problem causing a misfire?
So no not safe to say power pack is going yet...

 

[robstead]

Did some more diagnostics and kind of kicking myself in the butt because I assumed since I cleaned the carb and everything it was all good.

Found that the bottom cylinder is consistently flooding out, going to tear down the faulty carb and get a rebuild kit. Hopefully this is the fix as everything checked out, thanks for all the inputs to get me back on the water my MFG is getting dry lol

 

[Bosunsmate]

I make the valve, on that motor of mine, close a little earlier than it should so i dont get a flooding issue. Its never starved for gas even with this modification.
You need to check that your float is not rotten and that the valves close off the fuel flow. I do this by just turning the carb upside down and blowing in the entry fuel side, if you can blow any air into it then its worn and will be causing the flood out

 

[robstead]

Highly confused now, fresh gas, fresh spark plugs, fresh carb rebuild and floats are all good, still same issue?

Here's a video of the motor running, I have the air cover off right now which I don't think would cause an issue? All fuel lines good also.

https://youtu.be/xPv0a__tYo0

 

[robstead]

I pulled off the back plate for the Exhaust housing and found these pictures: http://imgur.com/a/kKoEa

The few things I noticed are, there's a rubber bushing around towards the top that looks mangled, not sure if that is the issue causing the motor to run bad as of right now but.

Also, that the unburnt oil/gas coming from under the cowling is coming out from right under where the crank case is. I ran the motor again for a few minutes to see and a little smoke will come from around where the oil is leaking then start running down the side.


With new reed valves, if one of the cylinders is running perfect but for some reason the bottom one keeps getting fouled, could the issue be deeper into the motor, and if so is it most likely a powerhead or crankcase issue?

 

[Bosunsmate]

Yep thats my motor, mine leaked a bit of oil there too until i changed the powerhead gasket but its not the most enjoyable job to do. And the reason for the excess oil and bad running could well be that your bottom carb is not closed at idle, look at your top one, its shut totally but your bottom one is ajar which will send too much fuel in and keep your idle too high and most definitely foul your bottom cylinder, Well thats my diagnosis at this stage

 

[Bosunsmate]

It sounds good as well so you a getting there, remember to change your telltale outlet to top of the crankcase when you have some time to do so

 

[racerone]

Bosun---In post # 22 you mentioned that reed valves might stay open at full throttle.----Any further comments on that.----Can you explain more about that ?

 

[robstead]

Yep thats my motor, mine leaked a bit of oil there too until i changed the powerhead gasket but its not the most enjoyable job to do. And the reason for the excess oil and bad running could well be that your bottom carb is not closed at idle, look at your top one, its shut totally but your bottom one is ajar which will send too much fuel in and keep your idle too high and most definitely foul your bottom cylinder, Well thats my diagnosis at this stage

How'd you go about changing the powerhead gasket? But I'll double check the carb, definitely not going to try and run it in the condition it's in right now if it's leaking oil like that.

And what do you mean the telltale outlet? Do you have a picture?

 

[Bosunsmate]

Bosun---In post # 22 you mentioned that reed valves might stay open at full throttle.----Any further comments on that.----Can you explain more about that ?

Haha no need to rub it in, you woman can do that when you get upset

 

[Bosunsmate]

How'd you go about changing the powerhead gasket? But I'll double check the carb, definitely not going to try and run it in the condition it's in right now if it's leaking oil like that.

And what do you mean the telltale outlet? Do you have a picture?

You have to undo the bolts you can see in your photo post, if they are seized its a big job, otherwise its not so bad. You then just disconnect everything from the base including the shift shaft and lift it off and replace. If its the gasket further down then you need to take off more parts, including bushings that connect to the transom bracket which is a much longer an dpain of a job but its normally the top one.
Id fix that carb butterfly up and see how you get on, it definitely is wrong
Yes ive a picture somewhere. Il have to find it but i need to go move some cattle.
Heres a link to the story about it
http://forums.iboats.com/forum/engi...aq/228380-johnson-evinrude-adding-a-tell-tale