‘55 QD-16 10HP Johnson - Fuel Issue

[Lukerevere]

I recently purchased a 1955 Johnson Seahorse 10HP outboard for a little fishin boat. In college and was in my budget but has been pretty cool to work on.

I can get it to crank with starter fluid but can’t get it to receive fuel. I changed the spark plugs, cleaned the carb and replaced the fuel lines.
It was not getting any fuel originally so I just rebuilt the gaskets on the fuel tank it came with. I got gas to flow by using an air compressor for the air line. I thought the engine would then do the rest of the work, but it appears to not be pulling fuel at all. This includes when it cranks over with starter fluid. Even with constant pressure from the air compressor, it sucks no fuel and also continuously seems to pull air into the line.

Not sure how to fix this other than I rebuilt the fuel tank incorrectly. (Or possibly the carb float, mentioned below.) Any advice would be very helpful.

Also,

Accidentally cracked the wooden carb float because I thought it was plastic and pulled the hooks out of it. Jerry rigged it in there for the time being and assume I have some time before it soaks up fully with fuel. Anyone know if a replacement exists?
Or a rebuild kit for the carb?

These carb tuning knobs are giving me a run for my money. Never seen anything like it. Thoughts on where to start them at to get her started? I am in Colorado at so a 5700ish elevation if that makes a difference.

Been using a 20:1 ratio for the gas. Is this correct?

Lotta questions but I’m a lot younger than the engine, still learning. Any help would be greatly appreciated.

 

[racerone]

When you operate the button on the tank it fill the carburetor with fuel.-----When motor starts it quickly pumps air into the tank.-----That pressure keeps fuel flowing.-----Does spark jump a gap of at least 1/4" on a test device ??.-----Have you looked at the coils through the inspection port on top of flywheel ??

 

[3rdtimesthecharm]

At 5700 ft. I don’t know where to set them. Usually I set the small knob 1 1/2 turns out from lightly seated and the large knob 3/4 turn out from lightly seated.

 

[racerone]

You dial in the lower one ( high speed ) first for best operation.----Then slow motor to idle and adjust the upper one ( idle mixture ) for best idle and smooth acceleration.

 

[F_R]

New Nitrophyl float is part number 0396514. Don't worry about the funky shape, that is because it fits other models also.

You are wasting your time unless/until you take a look at the coils. They are junk unless they have already been replaced.

 

[racerone]

24:1 was the ratio when new in 55.----Last year of those green ones.-----Check for loose wristpin bushings.---Also a common issue with them.------Today there have been many lively discussions about the mixture you can run with modern oils.-----No need to go into that again.

 

[Crosbyman]

if compression is ok ex; above 80 psi you must do the electricals on
these oldies .
coils if not replaced must be replaced
condensers likely no longer going their job
points need cleaning

should you dedide these motors are easy to cover to pump ify ou want to sue to modern fuel tank (one line) . the processinvoldes mounting a modern pump over a bypass cover or installing a nipple to get pulsing to drive a pump and changing the side fuel connector
see picture.

As a member you would have access to the the 400 page service manual.

see info

Troubleshooting outboard

Johnson

also thisseems challenging but it is a great hobby to restore these oldies and lots of help available here

 

[Lukerevere]

When you operate the button on the tank it fill the carburetor with fuel.-----When motor starts it quickly pumps air into the tank.-----That pressure keeps fuel flowing.-----Does spark jump a gap of at least 1/4" on a test device ??.-----Have you looked at the coils through the inspection port on top of flywheel ??

I have not looked at the coils at all. I understand the motor should be pushing air to keep the tank pressurized but it seemed like it wasn’t giving it enough pressure. Does the motor itself pull fuel at all or does it solely rely on the air pressure?

 

[Lukerevere]

if compression is ok ex; above 80 psi you must do the electricals on
these oldies .
coils if not replaced must be replaced
condensers likely no longer going their job
points need cleaning

should you dedide these motors are easy to cover to pump ify ou want to sue to modern fuel tank (one line) . the processinvoldes mounting a modern pump over a bypass cover or installing a nipple to get pulsing to drive a pump and changing the side fuel connector
see picture.

As a member you would have access to the the 400 page service manual.

see info

Troubleshooting outboard

Johnson

also thisseems challenging but it is a great hobby to restore these oldies and lots of help available here

Thank you so much for the help. It is turning out to be difficult but pretty fun learning how we did things back in the day. I’m still struggling with the fuel tank so might go the pump route. I was worried about the motor needing back pressure or something though. Does the motor actually need the pressure in the air line or theoretically could it just dump into the open if I have a fuel pump?

 

[Lukerevere]

New Nitrophyl float is part number 0396514. Don't worry about the funky shape, that is because it fits other models also.

You are wasting your time unless/until you take a look at the coils. They are junk unless they have already been replaced.

Thanks for the part. Do they also make any other newer parts like the pilot, gaskets etc? Just figure I should replace most things I can

 

[Crosbyman]

As a member you would have access to the the 400 page service manual.

update... sorry that comment holds true for AOMCI members... see what happens when you flip and flop from one site to the other

Forum: Ask A Member – Antique Outboard Motor Club,Inc

aomci.org

if you go pump just put a short stub of fuel hose on the air nipple and put a small bolt in it to plug i off. finish off with small tye wraps (zip tyes)

 

[racerone]

AS designed the motor pumps air into the tank until air pressure in the tank equals crankcase compression.----It maintains that pressure on the tank until tank is empty.----So with a fuel pump you have to block that air leaving the crankcase.