fuel pumps

[flatrod]

So it sounds like there are different pressures with different pumps. The engine runs fine with pressure set at 2 pounds, but when its shut off the pressure goes up to as much as 4.5 pounds, then one or two of the carbs fill up and starts to flood over. What is causing the fuel pressure to rise without the engine running?? Longest hose from the fuel pump to regulator is about 9 inches, I can't see that it is ballooning under pressure causing flooding. What is causing fuel pressure to rise when not running??

[dmsfrr]

Originally Posted by flatrod

... What is causing fuel pressure to rise when not running??

Assuming the fuel lines above the fuel pump to the carbs are all metal...
I'll guess it's heat soak.
When the car stops moving and the engine is shut off it loses two primary cooling methods.
The added heat from coolant not moving thru the engine and lack of air flow around the engine and even the lack of flow thru the fuel line could cause additional heat buildup in those fuel lines. The fuel trapped between the fuel pump & carb will attempt to expand an additional amount, increasing the pressure.
.

[Daves55Sedan]

Originally Posted by flatrod

So it sounds like there are different pressures with different pumps. What is causing fuel pressure to rise when not running??

If you buy a NEW fuel pump for a 272/292/312/FE engine, it will have a maximum output of about 7psi, regardless if you get the most common pump without the integral filter or not. The factory original pump had a much lower output pressure.
Same thing goes for the 223 I-block 6 pump, except it is a different pump and does not fit the Y-blocks. These also have a high output pressure.
Different engine manufacturers have different pump designs and output pressures to suit their overall fuel delivery system, including intake.
Having only ONE of the same type carb you are using makes me wonder if you have an auxillary electric pump back by your gas tank in the stuck "on" position that is feeding gas past the mechanical pump when the engine is shut off.
292V8-2.JPG

[Alaska Jim]

Not heat soak. I have installed spacers under the carbs. does not matter if the car runs 2 min, or 30 min. fuel pressure rises as soon as the eng. is shut off. there is no aux electric fuel pump. as I said before this combination ran for almost 5 years before this problem came up, and before I installed the spacers. I just installed them, in desperation. I did not think that was the problem, but I was willing to try it. car never runs more than 170 on the hwy. , and cools down to about 160 at an idle after it is warmed up. mechanical gauge does not increase more than about 10* at most after shut down. vehicle has no fenders , or hood, fan is 3/4 of an inch from rad. core. very doubtful it is a heat problem. Thanks for all of the suggestions .

[Alaska Jim]

Dave I am going to get an old rebuilt pump for a 55 Ford, and see if it will help. nothing to loose at this point.

[KULTULZ]

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[oldbird55]

new pumps are junk from china,If you have a old pump made in usa rebuild it.They are so bad some venders won't sell them.

[Alaska Jim]

No ethanol fuel in Alaska. I understand the deal about heat soak, but this is happening even with a cold engine, even if it is only run 2 minutes. I do not believe that the eng, gets warm enough to cause a heat soak problem in that short of time . the intake manifold is not even warm to the touch. Like I said. this car ran with this configuration for 5 years, until I changed from an Offenhauser, to an Edelbrock intake manifold. both 3x2 intakes, just different manufactures. I also know that these carbs do not like press. over 2.5-3.0 psi. I have tried 2 different holley low pressure fuel regulators and 2 different gauges with the regulators set as low as 1.5 psi. I do not really want to re-engineer the whole car and plumb in a return line,

[KULTULZ]

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[Daves55Sedan]

Jim, I would have suggested getting an original Y-block pump and rebuilding it, but the repo parts suppliers are not offering Y-block pump rebuild kits. They do sell flathead pump rebuild kits, but I don't think those will work for Y-block pumps.
I do know that the new pumps made in china have two valves in the bottom, one of which I believe is a check and the other a bypass, not sure. But if the bypass valve malfunctions, you could be pushing tons of extra volume up to the carb. And I can tell ya, those valves in the bottom don't always last very long on the china made pumps.
As far as building a bypass system back to the fuel tank, that can be complicated, because you need to install an orifice in the line heading up near the carb inlet that is the right amount to cause enough back-pressure to fill the bypass line. If that orifice isn't small enough, you may still have an overflow at the carb.
The worst thing about a bypass line, is you need to take out the gas tank, drain it and dry it out enough that you can weld a piece of tubing on at the top rear of the tank that will also clear the car frame and trunk floor.

[Alaska Jim]

Thank you everyone for your contributions. I have all winter to hash this out. there is no ethanol fuel in this part , or northern Alaska.

[Gene F]

Originally Posted by dmsfrr

A '54 fuel pump apparently has a different style actuating arm. Shown in photo # 1
The other two are '55+ examples.
.

Where do you get a filter for #3? I ordered one of the paper filter ones, but it does not fit.

[KULTULZ]

... the repo parts suppliers are not offering Y-block pump rebuild kits

Try Here - https://www.then-now-auto.com/

[KULTULZ]

Originally Posted by Gene F

Where do you get a filter for #3? I ordered one of the paper filter ones, but it does not fit.

What year? You show 54 FORD.

What the man said about WIX is truth. MOTORCRAFT is made by PUROLATOR to FORD specs. Good filter, but WIX is much better quality.