The Stovebolt Site Forums The Shop Area Engine Shop 235 fuel delivery issues... solved?

Shakedown trip to Carolina 2 weeks ago brought out some fuel issues. First was a no start condition after I arrived there and after I started it several times on Friday and Saturday morning. One of the local farmer-boys said "Crank'er up, let me hear it run." It wouldn't start for nothing. Messed with it till dark, slammed the hood and went in to watch NCAA basketball. Next morning I managed to get my head in far enough to blow through the gas line back to the tank. Bingo... started and I drove 125 miles back home with no issues. Monday I took the new sending unit out of the new gas tank, removed the collapsamatic sock screen and replaced it with the reinforced stainless screen out of the old unit. End of that problem.
#2 problem... fuel volatization when hot. Seemed like each time I drove 6 miles to the local gas/mini mart and spent 10 minutes, it would not start. Drive home, check for start every few minutes with no issues. Found out by cracking the carb gas line at the mini mart that it was under pressure.

Well, here is the fix I'm going to try... In the pic is a .050 carb jet, soldered to a 3 way fitting. I will hard line this into the fuel line from the fuel pump to the carb. Another line from the jet to the fuel line from the tank will give the unwanted pressure an escape from flooding the carb. There shouldn't be enough fuel flow bypassing the pump from a .050 jet to affect flow to the pump, but will providing bypass relief from volatile fuel pressure due to crummy ethanol fuel. Can't imagine how bad it will be when the temps get into the upper 90's.
Thoughts?
Jethro.

New tank in the cab. Gas cap vented. Not trying for fuel return but for pressure relief when engine is shut off at full operating temps.

No, the line attached to the jet goes back to the fuel line from the tank. Volatized pressure between the carb and fuel pump simply goes through the jet, bypasses the pump and goes back to another T in the fuel line from the tank.
Basically, it allows the volatized pressure buildup to bypass the pump's check valves and go back into the tank instead of pushing the needle off the seat and flooding the carb.

Does the '54 feed the carburetor through a sending unit instead of through the bottom of the tank via gravity?

I wonder if your vented gas cap is faulty?

I drove my '50 all last summer in Atlanta on crappy ethanol fuel but never experienced those problems. It has a mechanical pump.

Why not find and fix the high fuel pressure problem?

Or get a fuel pressure regulator and install it between the fuel pump and carb and see if that fixes your issue.

https://www.amazon.com/Mr-Gasket-97...hy=9007681&hvtargid=pla-568947605259

Mike B

If the gas cap in relatively new, it will have a plastic check valve in it. It has been my experience that this "check valve" is designed to prevent fumes from escaping the tank. I don't know if this was done on purpose, or by accident.
Regardless of that, an easy fix is to drill a simple 1/8" hole through the plastic piece. You don't need to drill into the center of this piece. There just needs to be a hole through it somewhere to allow the pressure to release

I don't have a cold start or even a warm start problem. Only when the engine is shut off at full operating temp. The under hood heat vaporizes the fuel, creating pressure that can push by the needle/seat and flood the carb after 10 minutes or so. I can crack the line at the carb immediately after shut down and fuel just drips as it should. Crack the line after 10 minutes and gas squirts out under pressure. I'm simply trying to relieve that pressure, therefore eliminate the flooded situation.
I have never experienced this with my old 51 216 or 56 235 or 59 235 or 57 261. But then, they were before ethanol fuel, which evaporates a lot quicker than "regular old gasoline."
ps... The nearest non ethanol gas is 25 miles away.
If this hack works it will only cost me 2 bucks out of pocket.

Carl... had to drill the cap when I installed the new tank. No problems there. Thanks.

That idea you have is a factory setup on a 74 Ford F350 of mine with a 460 engine but the return line goes directly to the tank. Never had an issue with too much or too little pressure at the carb

Jethro in Va. We done that too Pontiacs in the sixties

1960s Buicks had an inline fuel filter with an extra tiny nipple for solving a similar situation.

52Carl Your right hadn't thought of that in years,I think we learned to re-cycle fuel to help avoid vapor-lock.

Gosh fellas, sounds like I just re-invented the wheel.

Jethro: Brilliant! Couple of dumb questions from a novice. How do you plan on attaching to the "jet" nipple? Doesn't look like a flair fitting will work? Are the threads on that nipple pipe, flair, or compression? where did you get the tee and jet? Do you have Napa part numbers?
Thanks.
Dave