Carburetor Problem

Robert/Texas

Robert/Texas

Well-known member
My early ’28 open cab pickup is giving me a problem when I fill the gas tank. For example, after I left the gas station last week, it starved for gas. When I gave it full throttle and pulled out the choke, the engine started and I continued home. It has done this numerous times in the past but only when the tank is over around half full. Yesterday I took the car on an old oil field road and it stalled on me. I couldn’t restart it and the carburetor appeared dry. I walked home and returned in my modern car with some tools. I tried to start it but no go. When I removed the fuel line, it was full of gas but when I removed the drain plug it was dry. I blew and sucked into the fuel line and the engine started right up. I’ve owned this car for nearly 30 years. It has a Zenith carburetor with a stock type needle valve assembly. The float seems to move freely.
Any suggestions will be appreciated
Robert
 
Hi Robert,

Have you checked the fuel screen input (inside) the carb? I found mine to be clean but smashed because the fuel line had been inserted too far into the carb. It was fits and starts for a bit then nothing.

But if you have fuel up to that point, it has to be that screen or the float valve at that point.

Good luck,

JackD
 
Hi Robert,

It sounds like a fuel tank vent problem, or when refueling, rust and debris in the tank is getting stirred up and clogging the fuel pick up. I would check the fuel cap for proper venting. If ok, look for fuel line clogging.
 
Chris H said:
Hi Robert,

It sounds like a fuel tank vent problem, or when refueling, rust and debris in the tank is getting stirred up and clogging the fuel pick up. I would check the fuel cap for proper venting. If ok, look for fuel line clogging.
Click to expand...

I agree - check for rust and debris clogging fuel lines/carb screen
 
Thanks Jack Chris and SeaSlugs.
The screen inside the carb looks like new. I have two A’s and two T’s and have owned all of them for 28-30 years. All have had problems with stuck/leaky float valves over the years but this is the only where the float valve seems to be stuck closed.
The fuel line runs freely but maybe it’s the fuel cap. I’ll check on that first. I’m going to work on it after breakfast.
Thanks again and regards, Robert
 
The old repro gas cap has a round brass insert with three holes drilled in it. When I blow air into any of these holes, it only comes out the other two. I don’t see how this can vent to the atmosphere. What am I missing here?
I also checked the cast iron sediment bulb. There was no washer under the big brass nut and the screen was clean but damaged because of this. I replaced the screen and added a fiber washer. This would have allowed debris to pass.
As I’m confused over the gas cap I’m going to wait until I hear something about this before I start further tearing into things.
Thanks in advance, Robert
 
My 28 did the exact thing twice during the same very hot day. The fuel evaporated from the carb, and for some reason it wouldn't start flowing again until I removed the line at the carb, and as soon as the gas came out I screwed the line back on.

This was when I had the 10% corn crap gas in the tank. Since then I've only used gas without corn, and I add 4 ounces of MMO to each tank of gas. I haven't had that problem since doing this.
 
Robert/Texas said:
The old repro gas cap has a round brass insert with three holes drilled in it. When I blow air into any of these holes, it only comes out the other two. I don’t see how this can vent to the atmosphere. What am I missing here?
I also checked the cast iron sediment bulb. There was no washer under the big brass nut and the screen was clean but damaged because of this. I replaced the screen and added a fiber washer. This would have allowed debris to pass.
As I’m confused over the gas cap I’m going to wait until I hear something about this before I start further tearing into things.
Thanks in advance, Robert
Click to expand...

There are 6 thin slots around the perimeter of the cap, where the inner and outer join. Blow through them also.
 
Try driving the car with the gas cap only loosely placed on the fuel tank It would be open to the atmosphere then and you could eliminate the cap as the problem.
 
Two (2) possible quick and inexpensive Model A tests already herein mentioned above:

1. Possible Free Test One (1): If a non-vented gas tank cap causes fuel "not" to flow ..... just temporarily remove cap .... fuel should flow instantly ..... if fuel flows after removal, either provide vents in cap or buy a new gas tank cap.

2. Only $3.95 for Test Two: If adding gas moves rust & debris around in an 80+ year old Model A gas tank, and clogs the tank's outlet at the tank's shut-off valve, possibly stopping fuel flow, just install a Gas Valve Shut-Off Screen from Bert's, (Bert's Catalog page 44), Model A part no. A-9194.

A little patience, and just trying the old time Model A "One-By-One Method.

One-At-A-Time" ..... similar to shooting poisonous snakes in your swimming pool with your single shot rifle !!!!
 
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If I read Robert's posts correctly, "The fuel line runs freely" (post 5). I would think this would eliminate an unvented fuel cap and anything blocking the fuel flow prior to the carb.

Also, he only seems to have this problem when he fills the fuel tank (post 1).

I would be looking at the carb. Specifically the needle and seat.
 
Many thanks Tom. You’re my hero today.
My gas cap has only three of these slits and I think they were stopped up with the residue from the corn gas I’ve been using. I never noticed these slits before. This stuff has caused me much frustration over the years. The nearest gas station with ethanol free gas is about 70 miles away from me so I continue to use the corn gas. They have 93 octane at around $2.80/gallon where regular is around $1.88 here. I add Stabil to the corn gas and I think this helps some. I do use the ethanol free stuff in my chain saw and other small engines. In my cars that have glass sediment bulbs, you can see that the fuel turns yellow after a month or two and the yellow gets darker and darker. When I empty the bulbs I find that the fuel feels greasy and has very little smell.

Thanks too to you other posters. I think I remember taking off the gas cap before checking the flow. I'm thinking that this only happens when the tank is near full because of the extra air space in the tank when as it gets closer to empty.
 
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H. L. Chauvin said:
Two (2) possible quick and inexpensive Model A tests already herein mentioned above:

1. Possible Free Test One (1): If a non-vented gas tank cap causes fuel "not" to flow ..... just temporarily remove cap .... fuel should flow instantly ..... if fuel flows after removal, either provide vents in cap or buy a new gas tank cap.

2. Only $3.95 for Test Two: If adding gas moves rust & debris around in an 80+ year old Model A gas tank, and clogs the tank's outlet at the tank's shut-off valve, possibly stopping fuel flow, just install a Gas Valve Shut-Off Screen from Bert's, (Bert's Catalog page 44), Model A part no. A-9194.

A little patience, and just trying the old time Model A "One-By-One Method.

One-At-A-Time" ..... similar to shooting poisonous snakes in your swimming pool with your single shot rifle !!!!
Click to expand...

You have to aim where the snake isn't, due to the water bending the light rays. :D
 
No need to use the high octane fuel. It is more difficult for your A to burn. The high octane is for high compression engines to prevent pre-ignition. Your truck will run better on low octane fuel.
 
Robert,

We have the same issue here in the Mid-west; we have to drive a long way to get ethanol free fuel. I have been adding a good slug of Seafoam to my fuel to remove the deposits left behind by the evaporated ethanol. I have been using it in small engines for years for the same reason. It works!

The float needle in my Model A was seeping over the winter storage, and drained the tank. I added the Seafoam to the tank before filling up, and my problem went away. (For now, anyway.)

I am not a proponent of miracle liquid elixirs for cars, but this one seems to work.
 
When one DIED in the OLD days, whip off the gas line & use the hand pump to blow back through, "THERE SHE GOES" until the next time???
Bill Easy
 
I was having similar problems with my other coupe (Green Wheels) It would run perfectly till it wouldn't. Check your sediment bowl. Check your tank for rust particles . There is a long , very fine mesh filter at the tank connection. One giveaway is that the tank valve is hard to turn on and off also it may leak a little . My solution was a new little filter, rebuild the shut off , tank valve. And a new filter + the mesh screen in the sediment bowl and take the carb off and take it apart and clean it thoroughly. Then while you tank is empty, nail some fabric to a stick and poke around near the tank valve. This will pick up the rust particles. Then pour a little gas through the tank to was out the loose rust you didn't get with the stick. The I put a high powered magnet on the outside the tank a few inches away from the outlet. No problems since
Terry
 
Terry said:
I was having similar problems with my other coupe (Green Wheels) It would run perfectly till it wouldn't. Check your sediment bowl. Check your tank for rust particles . There is a long , very fine mesh filter at the tank connection. One giveaway is that the tank valve is hard to turn on and off also it may leak a little . My solution was a new little filter, rebuild the shut off , tank valve. And a new filter + the mesh screen in the sediment bowl and take the carb off and take it apart and clean it thoroughly. Then while you tank is empty, nail some fabric to a stick and poke around near the tank valve. This will pick up the rust particles. Then pour a little gas through the tank to was out the loose rust you didn't get with the stick. The I put a high powered magnet on the outside the tank a few inches away from the outlet. No problems since
Terry
Click to expand...

How can you poke around the tank valve?

Bob
 

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Thanks again to all.
I have pretty well done all of the things mentioned over the years including within the last year. I rebuilt the shutoff valve, which I believe is an original one, and it turns easily and doesn't leak. I really think that Tom's comments about the gas cap in post #8 has identified the problem. I'll report on this if the problem recurs. It got over 100 degrees here today which has discouraged me from driving the pickup.
 
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