1987 40hp Johnson won't run

MyWoody

Cadet
Joined
Oct 21, 2008
Messages
14
I just took ownership of a 1987 Sylvan Pontoon, 40hp Johnson VRO outboard. It had been sitting 2 years...

Cleaned out gas tank, refilled with fresh 93 octane.
New Plugs
New Battery
Pulled the carbs drained and sprayed clean, nothing more. Reinstalled.

Heres my issue: With the Manual Primer lever I can start it, but then it dies out. Over and over again, its sounding a ton better than when I started working on it. But it just keeps dieing out.

Any suggestions would be nice as I have only worked on 25hp, and 75hp, Johnsons in the past, and they just simply ran good...

Sold the Woody for something a little less time consuming, :rolleyes:
 

EGlideRider

Lieutenant Junior Grade
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Dec 14, 2008
Messages
1,000
Re: 1987 40hp Johnson won't run

You should post in the Johnson section for more results but sounds like the fuel pump. Given the age of the motor, I recommend you change it anyway. It's not hard to replace and not terribly expensive.

And while you are at it, change the water impeller and the lower unit grease.
 

J Hartman

Petty Officer 3rd Class
Joined
Jul 3, 2010
Messages
93
Re: 1987 40hp Johnson won't run

A good way to check if it is the fuel pump is to pump the fuel bulb when the engine first gets running. If the outboard continues to run, it is usually a good sign that fuel pump is bad. At least on older outboards I know you can check them like that.

Hope this helps.

J
 

MyWoody

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Joined
Oct 21, 2008
Messages
14
Re: 1987 40hp Johnson won't run

Need someone to pump the ball while I crank over, but I tried to start it a couple times, pulled the top carb off and went to drain it and nothing poured out. Could that be a simptom of a bad fuel pump?
 

MyWoody

Cadet
Joined
Oct 21, 2008
Messages
14
Re: 1987 40hp Johnson won't run

just uninstalled the oil injection system, blocked all the oil ports, and installed a mechanical fuel pump... haven't tried to start it yet.
 

MyWoody

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Oct 21, 2008
Messages
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Re: 1987 40hp Johnson won't run

So now it runs while choked, but it won't settle down to idle. Any suggestions?
 

Silvertip

Supreme Mariner
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Sep 22, 2003
Messages
28,758
Re: 1987 40hp Johnson won't run

You are doing everything to avoid rebuilding the carbs. The idle passages are very likely clogged. Spraying carb cleaning in the throat of the carb does nothing. You need to get inside it.
 

lmuss53

Lieutenant Junior Grade
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Sep 9, 2008
Messages
1,227
Re: 1987 40hp Johnson won't run

What Silvertip said.

If you've had them off and gotten them back on right you already know how to do the hard part. Get a manual and a clean bright area and do them one at a time, it's simpler than you probably think. Lay everything out as you disassemble and make sure you get everything back in. If you google "cleaning OMC 40 HP carbs" you'll probably find a photo slideshow or a youtube vid of someone doing it. You can probably download a pdf file of the disassembled carb to use also. I think you will be amazed that it runs at all after you see the inside of that carb that sat for years.

Trying to make a motor that isn't getting enough fuel run without fixing the problem is a good way to score a cylinder and get real bad problems. NEVER try to run a 2 stroke on anything accept the properly blended fuel. Adding something like Stabil or Seafoam to the fuel is OK but always start with blended fuel. The oil in the fuel is what lubes the engine.

After all that if you're still uncomfortable with the disassembly process take them off and take them to your favorite old school car mechanic or lawn mower guy, He should be real comfortable taking them apart and cleaning them up for you, without charging those boat mechanic labor rates.
 

EGlideRider

Lieutenant Junior Grade
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Dec 14, 2008
Messages
1,000
Re: 1987 40hp Johnson won't run

I just want to emphasize a remark by Imuss. Do not run the engine if it is starving for fuel. Running it lean can easily cause the engine to overheat and literally blow up.
 

MyWoody

Cadet
Joined
Oct 21, 2008
Messages
14
Re: 1987 40hp Johnson won't run

I will rebuild the carbs this week, looking forward to it since I have never done that before. Do you suggest I replace the floats as well? I see some kits don't include them and some do. Mallory verses Sierra rebuild kits, is one better than the other? I also read that there are fully rebuilt carbs for $80 each, how long would it take to rebuild a carb? Thank you guys for all your insight into my project.
 

MyWoody

Cadet
Joined
Oct 21, 2008
Messages
14
Re: 1987 40hp Johnson won't run

rebuilt carbs, wanted to fire right away, but then ended up flooded. Not sure if the choke lever/primer lever is moving the linkage to the carbs enough to use as a choke. We have not adjusted this since switching from VRO system. I'm waiting for the the last flooding to pass, and going to try starting with red primer lever.

Edit, also fuel bulb feels half full, could there be air in the system somewhere?

Any suggestions would be appreciated....
 
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