| Barney | -- 04-23-2022 @ 4:53 AM |
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Hello Ford Folks, I have a 1940 Fordor with the original engine (numbers match) that I believe has the original carburetor. As of recently, gas has been dripping from near the bottom of the carb after the engine is shut down. Also, the engine idles a bit rough and a hint of black smoke from the tailpipe is exhibited - obviously running too rich. The carb appears ok; the float level is within spec. Good gaskets, etc. Both my manuals claim the fuel pressure should not exceed 3.0 or 3.5 psi. Mine pushes 5.0 psi while running at idle. Anyone agree this could be my problem? If so, any recommendations as how to lower my pump's pressure? Thank you, Barney
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| 40 Coupe | -- 04-23-2022 @ 5:41 AM |
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It is not likely the fuel pressure increased suddenly. Is this car new to you?? If you have an original style mechanical fuel pump I would have it rebuilt by Charlie Schwindler in NY. It will be returned with the proper fuel pressure. It would be very unusual for you car to have an original engine that came with the car from the factory! As for the carburetor..... Ford factory did not put serial numbers on their engines. Fuel pressure should be 2 to 2.5 Yes 5PSI is way too much. Do you have an electric fuel pump? Yes I believe you may have found one of the problems, there could be another in the Carb.
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| trjford8 | -- 04-23-2022 @ 7:29 AM |
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I would send both fuel pump and carb to Charlie. If there is an electric pump involved it should only be used to prime the carb after the car has sat for a long time.
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| TomO | -- 04-23-2022 @ 8:03 AM |
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Excess fuel pressure could cause this along with other things in the carburetor. I agree with TRJ8 about sending both the carb and the mechanical fuel pump to Charley, Then you will have no use for an electric pump. If it was my car, and an electric fuel pump was installed, I would remove the electric fuel pump and splice in a new piece of steel line or better yet, replace the line from the tank to the firewall with a correct copper plated steel line available from Third Gen Automotive. A clean one piece line from the tank to the firewall allows the mechanical fuel pump to prime the carburetor in a few seconds, eliminating the need for an electric band aid. Charley Schwendler cas5845@yahoo.com Tom
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| Barney | -- 04-23-2022 @ 6:13 PM |
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Hello Mr 40 Coupe and all others Thank y'all for your expertise and advice. I stand corrected, 40 Coupe, the engine may or may not be the original. I believe the number is stamped on the bell housing portion of the tranny. When the engine/tranny assembly was shipped (with it's number) to an assembly plant, that number was then transferred to the recipient car's frame via manual stamping (per Cube's great book). I'm convinced my original style fuel pump is the culprit by producing a minimum of 5 psi at idle speed. I have no electric fuel pump. Most everything on this car is original. I'm very reluctant to send anything away for fear of never seeing it again (not because of Charlie, but because of shipping issues, especially the USPS). I'm planning to disassemble the pump to determine if anything is obviously awry. Thank you so much for your advise. Barney
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| TomO | -- 04-24-2022 @ 9:45 AM |
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The diaphragm return spring controls the fuel pressure. It is unusual for the spring to increase it's pressure. I don't know where you can get a new spring and if you do disassemble the pump, you should install a new diaphragm. The valves in the 1936-1940 fuel pumps are unique to those years and are not easy to find or replace properly. I strongly advise you to have the pump rebuilt by some one with lots of experience in the peculiarities of the pumps. It will save you a lot of headaches. I have attached a photo of the 1936-1940 style fuel pump. You will notice that the output port is lower than the input port. If this is the pump that you have, it should be rebuilt. If the input and output ports are equal in height, and you are not having your car judged as a Rouge car, I would replace the pump with a new one. If you are going to have your car judged as a Rouge car, contact Charley for an original pump. If you are concerned about USPS losing your fuel pump, ship it UPS or Fed EX and insure it for $400. That way if they lose it, you can get a replacement. The fuel leaking at the base of the carburetor could be a carburetor problem other than float level. Your power valve could be bad or your needle and seat could be failing, or your float could have a small leak. Tom
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| PeterFord | -- 05-10-2022 @ 1:34 PM |
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I had that. on my 51 F1 flathead. I installed a Purolator "Pro Fuel". regulator in the fuel line just ahead of the card. You can dial back the pressure or increase it. Worked fine.
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