Wild fuel pump

Sid

Sid

Well-known member
I have a mechanical fuel pump pumping fuel into an early Carter WCFB. I have been having problems with the carb. working fine then suddenly start running gas into the venturi's. I rebuilt the carb. and have been into it three times myself to check my work. Finally took it to a professional shop and he checked and rechecked and blew everything out and could not find an issue. Still have problem so now I check fuel pressure and have just shy of 10 psi and checked with 2 diff. gauges. Do fuel pumps have a bypass that can fail? Or how do they regulate their pressure? I bought a Mr. Gasket 8 lbs reg. set it at 2.5 and got pressure down to just over 4.5 but the reg. was leaking gas because it is only designed for 8 psi I really don't want to run reg. if I don't have to. What happens to a pump to go wild like this?. I realize 4.5 is about the max for this carb. Is there a way to open them up and re-set pressure? ....Sid
 
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I had the exact same problem with repro fuel pump for 223 I-block 6-cyl. Fuel pressure output from the pump is 7 psi (as per pump spec's), but that little Holley 1904 will only take about 2.5 psi maximum. The pump pressure was overtaking the float and flooding the carb. Yes, I also put in those cheapo inline Mr Gasket regulators that would blow up in a months time. Too much pressure for them. I ended up getting rid of the regulators altogether and got a Mopar bypass fuel filter installed ahead of the carb and ran a new bypass fuel line back to the gas tank. I added an orifice in the carb inlet tubing to create backpressure in the carb inlet tubing which causes the bypass line to start filling. Never had a problem with flooding since and I am running the car nearly everyday now, both town and highway driving.
 
The cute little chrome top regulators seem to leak, or not pass fuel at all. The more expensive Holley is available in two pressure ranges, and they work well. The low pressure gauges are often hard to find, Speedway has them. Some of the 460 powered F150 and F250's had a return line from the carb back to the tank. The last couple years of a carburetor equipped truck is where you look for this devise, it went into the carb and looks like a gold colored filter.
 
Did you try calling your local NAPA or other chain auto parts store and see what the maximum output pressure is on their replacement fuel pump? Maybe they offer a lower pressure.
 
I have a new pump coming Wednesday. It seems that if a pump is specific to a certain car & engine size that the pressure would be in the proper range. This car is completely stock with no mods. My thoughts are it didn't need a fuel regulator from the factory so why does it need one now? I would think that as a pump ages it would not produce as much pressure. I put on a Mr. Gasket regulator rated at 8 psi and it shot gas everywhere. With about 15 seconds of cranking the engine fuel pressure is about 9 3/4 psi. And this is not a performance pump. In my 50+ years of playing with cars I have never had this problem with electric or mechanical pumps. Usually a mech. pumps or it don't.
According to manual this pump is supposed to pump at 4 1/2 psi. I thought my gauge was wrong so I checked with a 2nd. gauge.
 
Sid said:
My thoughts are it didn't need a fuel regulator from the factory so why does it need one now?
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That's exactly what I said when I was having problems with the fuel pressure on my 223. So then I went to ALL the chain auto parts stores websites and looked up the specifications of their replacement fuel pumps and found that they are all specified to deliver 5-7 psi (which is more than the stock carb can handle). But as I mentioned, I invented a remedy that works. You may have other options. Try Summit racing and see what they offer.
 
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