Johnson Carburetors update

[TRP Hawaii]

I want to thank both of you, edinmass and C Carl for responding so quickly to my request for my sticky float valve.

I was presuming that the float valve is my problem but i am just guessing.

Some history of this problem may shed some light.  I have owned this car for almost 20 years now.  Never used anything but straight gasoline

The fellow that I bought this car from had installed an electric pump and a pressure regulator, and did some work on the internal parts of the 

Johnson carburetor. The car started normally and ran well.

For the next 10 years, I worked on finishing the restoration   I probably should have drained the carburetor  by running it out of gas, but I don,t

remember doing that.  After all this time, I started the car but... it was spitting out a lot of black wet smoke.  At his time I decided to  check out

the pressure going to the carburetor so I installed a pressure gauge between the pressure regulator and the carburetor.  With the car running,

the carburetor was getting 3 1/2 pounds pressure and 5 1/2 pounds  when I turned the ELECTRIC pump on.  The engine was barely running

and gas was dripping on the floor from the carburetor manifold.  No fire thankfully   Obviously the electric  pump can overwhelm the float valve.

Lesson....  Don't touch the electric  pump !!

So I  bought a carburetor repair kit from Classic and Exotic Services.  Something still wrong.  The only way I can get the engine to start is to

move the throttle to full open and quickly move it back once it started.  Not a good idea.  That is the situation I am in at this moment.

Once I get the engine running normally, I can then shut it down and it will then restart as it should.  This will last for about 2 or days.

Can not find a leak in the gas lines.   What prompted  me to start this discussion  was about a month ago when I had to get the car inspected

to renew the license .   Got to the inspection station, shut the car down and could not get it started again.  Had to have it towed home.

PANIC !!!!    Fortunately, the tow truck driver got it home without a scratch.  I gave him a $100 tip.  This has gotten serious now.  My says she 

won't go anywhere with me until I get the starting problem fixed.  So..  I hope this sheds some light on what I am doing wrong.

Any suggestion you old car people have will be greatly appreciated.   Terry 

.

 

[hidden_hunter]

I'm not sure how different that is from my much earlier car (carb is a similar design though) - but that sounds like too much pressure. For instance in 1922 it should only require 1lbs of pressure to start (mine starts fine on less than 3/4 lbs)

[Coley]

I am wondering what your car is.  I have had a 1933 Chevy 3 window coupe (no rumble seat trunk), for  over 50 years.  I see a 1933 hood ornament but a lot of differences.

Nice car.

[Matt Harwood]

1933 Cadillac.

[m-mman]

I have a 1929 Cad and I went through a steep learning curve. 

 

As originally designed the fuel delivery system is a vacuum tank.  Engine vacuum sucks fuel into a reservoir tank (for storage) then the fuel is delivered to the carb by pure gravity feed. (Model T style) 

No pressure. (well it has the pressure of a drop of 6"-12". . . 1 pound? half a pound?) 

 

What I discovered is that it is almost impossible to get an electric pump to regulate down to such a low pressure. The line and fittings to the carb are a large diameter so there is FLOW, just no pressure. 

Low pressure (adequate volume) is what the Johnson carb was designed for.

 

After that I climbed the mountain and repaired the vacuum tank. A story in itself, but I have been told that after you have one set up properly, they can work reliabily for decades. 

The electric pump is only for priming after long storage periods. 

[John_Mereness]

Doesn't 1932 and 1933 have a mechanical fuel pump hanging on the side of the crankcase ? 

 

If so, I would get that working again, wrap the lines, and wrap the exhaust anywhere near the lines and at the rear axle hump.

 

And, do not be afraid to call Classic and Exotic and ask for advice as there is a reason why they have made the kits. 

[edinmass]

The 32 and later eights had fuel pumps...........its been thirty years since I worked on one. Sadly carburation and ignition have evolved so much over the the last thirty years there are very few young people with extensive experience dealing with running issues. Add in the fact that the early cars are all significantly different its very hard to find people that know if parts are missing when they work on things.