1996 Johnson 50hp, Changed plugs, Problems! Please Help.

paul_yegr

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Feb 20, 2011
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1996 Johnson 50hp J50TLEDS

Okay. Engine would turn over and start, but usually needed to add a little throttle quickly to have enough RPMs to idle. When switching in to gear you have to move quick and give it some throttle so it wouldn't die; but it ran and was dependable at doing what it did.

It had been quite a while since I'd changed the plugs, so I did. When I pulled the old plugs it definitely looked like I got my money's worth out of them. I put the new plugs in and put a fuel treatment in the tank as I topped off about 10 gallons. Put the boat in the water, started up really quickly and nice with just a quick choke. Buddy drove it to the dock about 10 minutes away and tied it up.

Next day, got a call from buddy saying the boat was running well at low speed, but cutting out and stalling at upper RPMs to wide open throttle (WOT). Once before this happened, figured it might be the inline fuel filter. It's one of the glass ones with a screen that can be cleaned, not the throw away kind. Explained to him where it was and what to do. He seemed uncomfortable with it; either way we are on to the next day.

Boat runs fine again in the morning. For a little while. Then I get a call that says the boat is cutting out at higher RPMs again and that he has to give it more and more gas to start each time and that he just made it back to the dock and had to basically run it at WOT just to make it back to the dock and that it didn't have much power. I'm thinking 'I wonder how many times he's been starting it and hope he hasn't done any sever damage'.

I go check out the boat right then, it won't start unless given A LOT of throttle and when it does it sounds very bogged down, almost like it's running on one cylinder or like an engine sounds when it's about to be flooded out.

SO today, I pull the cowling off and it looks like some oil might have been leaking a little bit from the upper of the two plugs. Pulled the plugs and that top plug has some oil on the threads. Pulled the lower plug and that one looks dry and like I think it should. I gapped the plugs to .030, I know I should have done that when I put them in, but didn't know. (note: The gaps weren't more than .040 from the factory I don't think). I cleaned them with some ether and then replaced them. I then pulled off the air silencer scoop cover thing on the front of the engine, in front of the carbs. I pulled it thinking I could check and clean an air filter that I've never cleaned. There was no air filter; but there was a little bit of oil in the cover.

Put everything back together, thought I'd crank it over just to see if a miracle occurred. Starter engaged the flywheel and stayed there. Didn't spin the flywheel. Thinking I need to put a charge on the battery, but also wondering why the bendix didn't retract. I manually wobbled the flywheen a little and the bendix is still stuck up.

Currently the battery is on the charger. Thoughts?

Thank you ahead of time for your time and thoughts. I can't wait to get this all solved. I love this little boat and it's been so good to me over the years.
 

boobie

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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

The bendix will retract when the motor starts. Have your battery load tested.
 

bob johnson

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Feb 25, 2009
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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

you might be getting too much gas at idle or low rpms.....for whatever reason....

because when you give it more rpms you are giving it a lot more air....

i had an issue with a motor that was flooding because the primer valve was flipped to open....and I was just getting all the gas the pressureized fuel line could give it!!!

but the motor would start when I put it in nuetral and gave it a LOT of throttle.....id have to rev down and shift fast and get the throttle back up...FAST to keep the motor running


that sounds a lot like what you describe....maybe your float is stuck open....not sure...

good luck


bob
 

bob johnson

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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

ps... I think your motor has the red primer valve lever..... it should be down when running normally....if you flip it up....gas will just pour into the manifolds...bypassing the carbs( thats how it works on a v 4 anyway).....when down the fuel line pressure is held steady... and when you prime with the key( push), you get shots of gas into the manifold....

bob
 

paul_yegr

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Feb 20, 2011
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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

I'm taking the battery off the charger now. Gonna mount it back up and check that.

Bob Johnson, I am having an issue with that little primer box, when I do push the key in to choke it I can see fuel spit out (into the cowling cover if the cover was on) like there is a crack in the box or a hose or something. I'm going to go look and see which way the red indicator is flipped.

How would that correlate to the engine dying at high rpms though; when it has been running okay for a little while and then dying at WOT. like descriped in my post.

Thanks guys!
 

racerone

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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

The trouble shooting on these 2 cylinder motors MUST include a compression test !
 

bob johnson

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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

I'm taking the battery off the charger now. Gonna mount it back up and check that.

Bob Johnson, I am having an issue with that little primer box, when I do push the key in to choke it I can see fuel spit out (into the cowling cover if the cover was on) like there is a crack in the box or a hose or something. I'm going to go look and see which way the red indicator is flipped.

How would that correlate to the engine dying at high rpms though; when it has been running okay for a little while and then dying at WOT. like descriped in my post.

Thanks guys!
I thought i was reading the motor wouldn't stay running at low speed, but only ran good at high speed

I would bet you have a split hose, or a bad o-ring....very common......I actually need to replace the Oring on my motor

P S no matter, what, you have to fix the gas flying inside the cover problem!!!!!!!!!!!!

bob
 
Last edited:

paul_yegr

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Feb 20, 2011
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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

I thought i was reading the motor wouldn't stay running at low speed, but only ran good at high speed

I would bet you have a split hose, or a bad o-ring....very common......I actually need to replace the Oring on my motor

bob

In the beginning it ran just fine at idle and cut out at WOT. Now it doesn't want to run well at idle and it takes WOT just to keep it alive and sounds like it's bogging. When you say split hose or a bad o-ring. Are you talking about on the fuel line or what?

Thanks
 

bob johnson

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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

In the beginning it ran just fine at idle and cut out at WOT. Now it doesn't want to run well at idle and it takes WOT just to keep it alive and sounds like it's bogging. When you say split hose or a bad o-ring. Are you talking about on the fuel line or what?

Thanks
no I am talking about exactly where you see fuel coming from, when you say gas is squirting on the inside of the cowling!!!!!!!!


take the cover off and look at the motor closely when someone squeezes the primer bulb....
 

firechildc

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Sep 24, 2011
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Re: 1996 Johnson 50hp, Changed plugs, Problems! Please Help.

I've got a 96 johnson 115hp and had the same problem. Motor would flood REAL easily. When putting in gear I had to throttle up real fast to keep the engine from dying. However, it ran like a dream at WOT.

On mine, that little red lever on top of the engine was the culprit. It's a crappy plastic lever that has a little o ring down in the base of it. With mine the plastic had cracked and fuel would leak out every time I pushed the key in to prime it. Luckily, it's a real cheap fix (not a phrase you hear often with boat motors). West Marine had the part for bout 6 bucks or so.

Hopefully that's the same problem you are having. Keep us posted.
 

paul_yegr

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Feb 20, 2011
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I did a compression test today. I had less than 15psi on the top cylinder and about 40 on the bottom. How f*&(&ed am I?

Thank you so much in advance...
 

racerone

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You have a bad compression tester or a motor in bad shape.---Remove cylinder head for inspection of head gasket / cylinders.
 
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