1956 Johnson 10hp QD-17 Carb rebuild screw-up

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BTF112989

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Hey everybody. I have a 1956 Johnson QD-17 that was surging & acting erratically. I figured the carburetor was gummed up, so I ordered a rebuild kit & completed a rebuild. I was very careful, did not rush(took me 3 hours), and put everything back as I had taken it out. I went to the top secret file & printed off the instructions on how to adjust the carb needles after a rebuild. When I put the boat in the water to test out the rebuild, the motor would not stay running. The longest I could get it to run was about 15-20 seconds. I took the cowling off & sprayed some ether in the air intake. As long as I spray ether in the intake, the engine will stay running. So, obviously the motor is not getting enough fuel. What did I do wrong during my carb rebuild? I made sure the float was level.

Can anybody give me somewhere to start on correcting my botched carb rebuild?

Thanks!
Ben
 
samo_ott

samo_ott

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

Something went wrong. Sounds like a low speed circuit gum up. Did you remove the welsh plug at the top of the carb and clean in there and replace it with the one from the kit?
 
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F_R

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

Many carburetor problems-----are not. Have you checked the ignition system? Sure sounds like the old cracked coils story. Ether is so flamable that it will fire on little or nearly no spark.
 

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1946Zephyr

1946Zephyr

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

Yep, F_R is right. I made this point a lot of times too. A faulty ignition system can lead a lot of us to believe our carbs are boogered up. All you need to do is remove the pull start assembly and then there should be a thin aluminum inspection plate that you remove, to get a visual of your coils. It's a tear drop shape with one flat top screw and three button head screws. Rotate the flywheel, in the clockwise direction only and you can see each of the coils. Number one coil will be directly in the front, towards the carb and number two will be directly towards the back, towards the cylinders.
 
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BTF112989

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

I'll stop using the starting fluid to test it out. The kit came with all new gaskets which I used, so where would be the most probable place for an air leak? Should I have used some sort of sealant in addition to the gaskets? The carb bowl has fuel in it.

Is the welsh plug made out of brass? I remember there was a larger-sized, brass looking screw that would not come out. I ended up stripping it out trying to get it out, then I ended up having to use an ez-out. I got it out cleaned around there & replaced it with the new screw provided.

Well the engine was running great(best running engine I have) right before I cleaned the carb. I bought this engine & my 35hp a little over a year ago. When I bought it, the guy said he had replaced the coils. I will check through that inspection plate tomorrow when I am near the engine.

If it is not the coils, what is my first step? Just tighten all of the screws even more to stop any possible air leaks? Then if that doesn't work, take it apart again & check the low speed circuit behind the welsh plug?

Low speed was never a problem before the rebuild. Problems just happened at higher speeds.

However, I have noticed that it would surge every minute or two when I was running at high speeds ever since I bought it. Whenever that happened, I would push in the primer button & it would seem to surge back to life.(I thought it was a leaky tank at the time). Once the surging happened alot more, I decided to rebuild the carb.

Thanks guys!
 
lindy46

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

The welch plug is made out of aluminum, and you should have a replacement in your carb kit. I usually drill a small hole through the old one and pop it out with a small screwdriver. If pumping the primer button on the tank stopped the surging, you may not be developing proper pressure in your tank. There is no fuel pump, so the motor relies on pressure build-up in the tank to push fuel into the carb. Pushing the primer button does the same thing.
 
1946Zephyr

1946Zephyr

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

Well, if your coils are new, then you're that much ahead. What lindy46 here says is a good point also. Just release the cap on the tank after a few minutes of running, to see if it's building pressure. If it's not, then that could be your issue. Don't use any sealer on the carb gaskets. You can use a light film of sealor on the carb to intake manifild, but no where else.
 
Steve A W

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

The welch plug is #39 on this parts breakdown.

http://www.marineengine.com/parts/v...ntage-evinrude-johnson/376747/37674700001.htm

When You drill it out dont let the drill bit go any deeper than an 1/8 inch or You might damage the carb.
There is a Youtube video about rebuilding an OMC carb
I'll see if I can find it.
Good Luck.
Steve A W

Here's a link to a series of videos, the carb rebuild is about 1/2 way down.

http://www.youtube.com/user/PistonPumper
 
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samo_ott

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

I would not drill out the welsh plug as little filings could clog the ports. I use an awl and punch a hole in it and then pop it out. Clean the little holes inside. I use cutting torch tip cleaners (also good for getting your shower head working well!) to clean the holes. Then put the new plug back in and use a smaller socket or a large punch to tap it in and lock it in. I put red silicone on it when I am done to a) seal it and b) I know that when I get to the engine again that I have rebuilt it.
 
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F_R

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

Um, ok it surges and recovers when you push the primer button, eh? Well that strongly suggests the fuel filter is partially clogged and not allowing fuel to enter the carb as fast as the motor consumes it. That motor has a sintered filter element in the glass bowl. They can look fine and still be partially clogged. Some people claim they can clean one, but I find it nearly impossible to get it really clean. You are supposed to just replace it. Just for a test, remove the filter and see how it runs. Actually, there is a filter screen in the tank too, but they aren't noted for clogging so easy---unless it is gummed up from rotten gas..
 
kfa4303

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F_R

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

1956 does not have a fuel pump, nor a vented tank. The pressure tank must NOT be vented.
 
1946Zephyr

1946Zephyr

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

It's funny. Out of all the carb rebuilds I have done, I have never removed the welch plug on the low speed circuit. I never really had a need too. I soaked my parts real good in chem-dip and got them spotless and blew out all the passages with air and things seemed to work just fine. After I remove the needle and old packing, I would just blast it out in there with carb cleaner.

And yes, on that model, you want the cap tight on the tank, or you won't get fuel up in the carb. You might also make sure that your tank is also getting pressurized. After you run it for a few minutes, you can loosen the cap to see if it de-pressurizes. If no air pressure comes out, then you have a different problem and you're just spinning your wheels on the carb issue.

On that model, it's easy to convert it to the single line system. All you need is a bypass cover and fuel pump for a 1961 - 63 10hp model and it'll still look factory. Also replace the nipple on the intake with a small plug too, so you don't get fuel mix spraying around inside your engine compartment.

Those are the best models of QD's you have there. They have the 5 bolt lower unit, that also was used on the 18's and they held up much better than the lower units they put and the '58 and later models.
 
kfa4303

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Re: 1956 Johnson 10hp QD-17 Carb rebuild screw-up

Doh!!!! Good catch F_R. No fuel pump on that '56 model (maybe I was thinking '59?). You should have a 2-line, pressure tank set up instead. You can convert it to a fuel pump in the future if want, however. I agree that the motor is worth the effort to get running.
 
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