1967 80 HP Johnson-gas overflowing in carburetor vent

[FTD26]

Have a Johnson 1967 V4Al-19R 80 hp. When I move the choke lever from automatic to "Off" - gas pours out of the vent hole in the starboard carburetor. When I move the lever back down towards automatic, gas is still in the tube, but not over flowing. (this model has two downdraft carburetors). After a short time- unless I'm running full throttle- the two plugs on that side quickly foul out. Any ideas? (I also have a short video but I'm not sure how to upload that)

 

[F_R]

Well that certainly is interesting. That hole is way above the normal fuel level in the float bowl, and gas should never be that high. Have you had it apart for a looksee? If I had one, I'd be doing an exploratory.

Looking forward to a video.

 

[FTD26]

I have a 3 Second video, but it's still 7.41 Mb. Not sure how to post it. I haven't taken anything apart yet. I have an old set of carbs from a 1966 Evinrude 80 Hp. Thinking of rebuilding them if it's only a carburetor problem

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[interalian]

Upload to YouTube and link here.

 

[FTD26]

I'll try to post this video of the 80HP carburetor overflow, let me know if it works..

FTD26

 

[FTD26]

Not sure what the other AD videos are on there for. Is there a way to up load with out all that extra stuff?

 

[F_R]

Never have experienced anything like that. I wish I had a diagnosis, but I don't.

 

[Willyclay]

Look at my signature and you will understand why I depend on F_R to keep me straight! That said, after I read your thread earlier today, I dug around my parts bin and found a carb like yours. I only had time today to blow air through the fuel inlet and observed air escaping that "hole" when my Choke lever was in EACH position. I cannot answer why gas is coming out of that location on your carb but will crack mine open tomorrow and look for an answer. Good luck!

 

[Willyclay]

Sorry but I did not have a chance to tear into that carb today. Tomorrow looks good.

 

[interalian]

Can you recreate it by squeezing the primer ball when the motor is off?

 

[FTD26]

Thanks, (from another Geezer) I noticed when I moved the choke lever back down to automatic, that the gas would still be in the vent tube, but would just down lower in the tube,so it did not overflow, but is still in the vent hole...

Right now the boat is in the water on Keuka Lake so I can't test squeeze bulb idea right now.
I picked up a carb kit for my extra carburetors. Any hints on how to best rebuild them? like how do I make a "Jet Screw driver" to remove the low speed jets etc?

 

[racerone]

The special / modified screwdriver is used for the high speed jet / orifice plugs.

 

[Willyclay]

Tashasdaddy, may he RIP, left that info as part of his legacy on the forum. Check out the link below. Good luck!

https://forums.iboats.com/forum/eng...aq/250235-carb-cleaning-instructions?t=244013

 

[Joe Reeves]

Gas pours out of the vent hole in the starboard carburetor.

There's only one downdraft carburetor on that engine. If the float is adjusted properly and the float needle valve isn't flawed... your problem is that the air vent to the float chamber is clogged, fouled, gummed, whatever.

Yeah I know those vents are difficult to find but clean it out and you'll be fine. The fouled vent creates a scenario whereas the air can't get out to allow the fuel to get in and as a result... for some reason... what you're experiencing takes place.

Don't try to figure it out... you'll go nuts!

 

[FTD26]

Thanks, Yes you're right, it's a Type IB Downdraft, double barrel with fixed high-speed orifices and low-speed needle valves.I have an extra one to rebuild (I hope) and then will switch it out with the over flowing one.

Two questions on the rebuild.

1) I don't have the special tool to unscrew the high speed orifices, and I didn't really understand Tashasdaddy's picture on how to make my own, so I left them in place- I removed the screw and cap on each one and cleaned them out.I can see day light through them. Is that good enough?

2) On the low speed jets, my seloc diagram shows four washers going in with the low-speed needle and gland nut. The rebuild kit has two black fiber washers, and two nylon washers for each jet. It looks like maybe they show nylon,fiber,fiber, and nylon- in that order. Anyone know for sure?

 

[Joe Reeves]

Yes, your assessment of.. "The rebuild kit has two black fiber washers, and two nylon washers for each jet. It looks like maybe they show nylon,fiber,fiber, and nylon- in that order. Anyone know for sure?".. is correct.

The high speed jets.... carefully clean them out (in place) with a piece of single strand steel wire as solvent just doesn't do that job properly.

 

[F_R]

Yep, the two soft packings are sandwiched between two nylon washers.

 

[FTD26]

Thanks for the help, I plan on switching out the carbs tomorrow, but I wonder if I installed the tube plugs properly: On first try one of the really small plugs blew out when I blew air into one of the openings- I replaced it and hammered it in with a rounded over punch. (On the bigger plugs I used a socket extension.)

Did I over do it? Does the carburetor create a lot of internal pressure that could blow any of the plugs out?

 

[F_R]

The goal is to flatten them with a suitable flat ended tool. If you go beyond flat they will get loose again.

 

[FTD26]

Thanks, Well I switched out the carburetor last fall, and it seemed to idle and rev up just fine, so I tried take it for a run- It ran fine, at full power for maybe five minutes, and then lost power and ran slower and slower untill it finally stalled out. It wouldn't restart- I tried choke on/off, squeezing primer bulb etc. The plugs weren't fouled, almost seemed out of gas
.I had to be towed to the launch ramp, and haven't tried it since.
Any ideas? I thought the new float might have gotten stuck, but it doesn't seem it would run more than a couple of minutes like that? Fuel pump? (The sediment bulb stayed full though)

thanks, Frank