54 fuel pump low pressure

[Joe R.]

I'm racking my brain here.

I have had an issue with my 54 fuel pump losing pressure after about 5 minutes of running. I set up an in-line pressure gauge at the front carb and it showed a 6 Lb pressure at cold operation. After about 5 minutes of running the pressure has dropped to less than 1/2 lb. At first I suspected the fuel pump diaphragm, so I rebuilt the pump, replacing both the fuel and vacuum sections diaphrams and check valves. Still the same issue. I also tried running a hose line from a can of gas to the pump inlet, eliminating any vacuum leaks in the tank line. Still drops to 1/2 lb!

What the he__

Any suggestions anyone?

Joe

[Roy B.]

Re: 54 fuel pump low pressure

I'm racking my brain here.

I have had an issue with my 54 fuel pump losing pressure after about 5 minutes of running. I set up an in-line pressure gauge at the front carb and it showed a 6 Lb pressure at cold operation. After about 5 minutes of running the pressure has dropped to less than 1/2 lb. At first I suspected the fuel pump diaphragm, so I rebuilt the pump, replacing both the fuel and vacuum sections diaphrams and check valves. Still the same issue. I also tried running a hose line from a can of gas to the pump inlet, eliminating any vacuum leaks in the tank line. Still drops to 1/2 lb!

What the he__

Any suggestions anyone?

Joe

Heat related bad pump housing warped or crack.

[Russ U.]

Re: 54 fuel pump low pressure

I believe that the 53-54 fuel pumps should run at 3 to 5 lbs of pressure. If you get more than that, you will have a leak problem.

My pressure starts off low, and then builds up as the engine gets hot. I think this is the way it is supposed to work. I recall seeing a very old Restorer article, maybe by Sam Folz, who when thru the problems that high pressure can cause. Starting off at 6lbs is not a good thing. And anything more than 5lbs can create leak problems at the carbs. That's why many 53 to 54 owners put fuel pressure regulators on their cars in the 60s and 70s.

I have a fuel pressure gauge in my 53. The pressure reads very low (darn near zero) until the car has been run for about 10 minutes, and then the pressure increases to the 3 to 5 lbs range. I don't know if I trust the pressure reading entirely, however.

Does you car run okay? If it does, trying running the car for awhile and then retest the pressure.

The best alternative may be to buy a NAPA fuel pump and see if that makes a difference.

Tha's my two cents worth...

Russ

[Joe R.]

Re: 54 fuel pump low pressure

Thanks for the reply Russ and Roy.

The engine runs great until it gets to about 170 degrees water temp. Then it stutters and eventually stalls out. It will restart in about 5 minutes but goes through the same scenario again. At 6 lbs I have no leak problems at the carbs. I'll try a new pump as a last resort, but really want to find the source of the problem.

[Dale S.]

Re: 54 fuel pump low pressure

The new ethanol fuels cause vapor locks, that you did not have a while back. I was talking to a bunch (!0 or 12) of 55-56 T bird guys and they have all gone to electric pumps at the tank. They were all vapor locking. I understand it is worse at 5000 foot altitude. Just a suggestion it may not be you but the fuel. Dale