Carburetor or Fuel Pump Issue My 46' Super De Luxe fires off in less that one revolution when I hit the starter button.......usually. If she sits for 4 or 5 days I have to put a little gas in the carburetor to get it to start. Sometimes I can see the low fuel level in the sediment bowl. If I drive around and shut the warm engine down, and let it cool, she turns over a few revolutions before she fires off. If I start it periodically and let the warm engine cool down slowly she fires off in less that one revolution and will start that way cold. It's like the fuel is cooking off from the carburetor or it's losing its prime. I see no fuel leaks. I'm not sure when she started doing this but the fuel pump has been replaced and so has the flexible fuel line. Do I have a carburetor issue or a fuel pump issue?
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Re: Carburetor or Fuel Pump Issue Let's start by checking a couple of things...could be defective fuel pump diaphragm or power valve. Depending on how old they are, I would consider replacing them. At least you've taken a couple of potentially troublesome items off the table.
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Re: Carburetor or Fuel Pump Issue Power valve? Where is that located?
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Re: Carburetor or Fuel Pump Issue Separate the alloy (pot metal) upper carb body from the cast iron base which has the throttle butterflies. Look at the underside of the pot metal carb body and you will see a valve screwed into it. This is the power valve. If they are old, they can fail to operate correctly or leak and cause the float bowl to empty into the intake manifold causing a flooding condition. Most new carburetor kits will have a new power valve, or you can purchase one separately from some of the Early V8 parts suppliers.
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This point needs clarification: New power valves have an incompatible base to the old carburetors, as the old had a flat surface of the sealing base, the new have a radius. These new units can be machined in a lathe to fit, or if buying from a supplier, verify that operation has been done. Alternatively, I've heard that some have used an el-cheapo method by utilizing two washers instead of the correct single, but as this seal is critical to the operation of the valve, I cannot recommend this method. |
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Cold starts can be helped with an electric fuel pump and a spring loaded switch so it doesn't run all the time, just for priming. The carb wants only 2-3 lbs of pressure. |
Re: Carburetor or Fuel Pump Issue What Chuck said x 2. Fuel today is crap & causes problems. Chuck stevens gets my vote before you start tearing stuff apart.
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I, for one, would start by checking ALL the fuel line connections and make 100% sure ALL are tight and not losing "seal". Then you can look to the above stated issues OR if you want to make sure all is 100% correct.....Box your carburetor and fuel pump up and send them to Charlie Schwendler, 5845 Cole Road, Orchard Park NY 14127......He IS the carb and fuel pump man and will make them right. I include a signed check with my stuff I send him and he calls me and lets me know whats what and sends my stuff back. Top notch fellow!!! I NOW have the same problem with my 39 Mercury, which I didn't have before I ran it out of gas.....I added an inline fuel filter at the rubber line from the firewall to the fuel pump and I suspect that one of the ends of my ADDED fuel filter is not 100% tight and is leaking vacuum over several days. |
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Do you have Charlie Schwendler's phone number? You can PM it to me. I think it would be appropriate to talk before I send him parts and a blank check. |
Re: Carburetor or Fuel Pump Issue Good morning! Thanks, mcgarrett !!! My first day in the barn and your answer to Mountain Dew may have helped me solve a problem I'm having with my Holley 1901 teapot carb. ..... fuel bowl emptying.
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Here is Charlie's contact info. It has been posted on my forums so no worry about putting it out there. 716 662 [email protected] |
Re: Carburetor or Fuel Pump Issue For what it's worth, the link below shows a range of power valves available from Holley. I don't remember off-hand the correct vacuum rating for the one used in the Holley 94's, but someone here on the Barn will know. They work based on manifold vacuum and there are many varieties with different vacuum ratings as you can see...
https://www.holley.com/products/fuel.../power_valves/ |
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Kube has advised to close the choke all the way when parking for storage, as that may delay evaporation somewhat. |
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Re: Carburetor or Fuel Pump Issue Common problem I have heard is the gasket on top of the glass sediment bowl. Slightest air leak anywhere on the suction side of the fuel pump is a problem. Pump will suck air before it sucks fuel. Easy thing to try first is remove the sediment bowl and clean/reset or replace that gasket.
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Re: Carburetor or Fuel Pump Issue Had a similar issue. It had a Rebuilt fuel pump & carb. The aux. elect fuel pump added solved this issue. I wired it thru a momentary-off-on switch & use it to prime and backup my mechanical pump.
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Re: Carburetor or Fuel Pump Issue Install an electric fuel pump at the tank operated by a switch on the dash, which in turn is connected to the ignition side of the ignition switch. Using longer carb studs, put 5 carb to manifold gaskets under the carb. Prevents heat soak into the carb.I no longer have the hard start problems. It has not been discussed, but is the line from the tank to the fuel pump good or does it have holes - turning on the electric fuel pump at the tank will show a defective gas line. I installed a 5/16ths copper line in 1988 and no problems. I used a neoprene gasket on the mechanical fuel pump filter bowl - cork can develop an air leak.
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