Re: [FWDLK] Carburetor / fuel Problems

[John McCann <jmccann@xxxxxxxxxxxxxx>]

    Have you checked the accelerator pump operation when the engine has been running recently to insure it is operating? The acceleration pump cup if it is the leather one might dry up after a period of time and not operate even though there is fuel present. The float chambers don't have an outlet that is below the fuel level, the flow of air through the carburetor venturi lowers the pressure in the venturi and causes the fuel to flow through the main or idle jets into the air stream supplying the engine with a combustible mixture, the choke plate increases the difference in pressure for increased fuel flow to a cold engine. You should run your engine for a longer time when you get it started, running it for such short spurts causes more wear than warming it up and getting oil distributed throughout the engine.

John

----- Original Message -----

From: mrdonr@xxxxxxxxxxx

To: John McCann ; L-FORWARDLOOK@xxxxxxxxxxxxx

Sent: Wednesday, September 05, 2007 12:55 PM

Subject: Re: [FWDLK] Carburetor / fuel Problems

A lot of people have suggested the fuel pump might have a bad check valve. That should be a fairly easy and inexpensive fix for this vehicle. I will try it in the next day or so and let everyone know.

 

To clarify my problem a bit more: There is a clear glass inline filter between the fuel pump and carb. It will be completely dry after a couple days of sitting. I also remove the air breather and manually work the carb linkage but the jets do not squirt anything. I had thought about the fuel pump check valve causing lack of fuel in the lines but why would the carb be dry too? 

 

I usually only run the engine for less than 5 minutes at a time so I didn't think it would be getting hot enough to percolate the fuel out. Don't you usually hear hissing/popping sounds immediately after the engine is shut off when this happens?   

 

Thanks again for everyone's help!

 

Don Roberts  

KC, KS

1958 Imperial x4

1967 New Yorker

 

 

----- Original Message -----

From: John McCann

To: mrdonr@xxxxxxxxxxx ; L-FORWARDLOOK@xxxxxxxxxxxxx

Sent: Wednesday, September 05, 2007 12:06 PM

Subject: Re: [FWDLK] Carburetor / fuel Problems

    I don't know how you determined that all the fuel drained back into the tank after your car sits a few days but I think it is unlikely that it is happening, I have heard of Carburetors percolating the float chambers dry from heat but that would only seem to affect the carbs while the engine was hot. Have you tried loosening the fuel line at the fuel pump that goes to the carb to see if any fuel leaks out after the car has sat long enough to have a problem starting? The one thing I can think of that might cause the fuel lines to bleed down is leaking check valves in the fuel pump allowing fuel to leak through the fuel pump and back to the tank, they are just spring loaded poppet valves with phenolic disc that seals the diaphragm chamber when it isn't activated to allow fuel to flow by the diaphragm movement, I believe there are two inlet and two outlet valves but there might just be one for each function, it's been a long time since I had one apart.

John

----- Original Message -----

From: mrdonr@xxxxxxxxxxx

To: L-FORWARDLOOK@xxxxxxxxxxxxx

Sent: Wednesday, September 05, 2007 10:07 AM

Subject: [FWDLK] Carburetor / fuel Problems

While on the carburetor topic, I have a problem that I could use some help with on my New Yorker (440 engine-Carter 4 barrel). It generally starts and runs good but if I let it sit for more than a couple days, it has to pump fuel all the way up from the tank. When this happens I generally just pour gas down the carb to prime it.

 

What would cause the entire carburetor, fuel pump and all the lines to drain? Is this some sort of siphon problem? and is it from the tank or motor? There are no leaks anywhere that I have found. I have considered getting an inline filter with a check valve but I would really like to find out the cause of the problem rather than just temporary fixes. Any suggestions would be appreciated.

 

Thanks,

 

Don Roberts  

KC, KS

1958 Imperial x4

1967 New Yorker

 

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