We had around 30 degrees Celsius (86F) in sweden (Hot for being here!) last week when I was out driving. After 30 min the car started to run quite bad, like out of gas. And misfiring.
When I checked the fuel filter it was empty. I suspected vapor lock or maybe the fuel pump. After a while I started it up again, I could se that some bubbles came with the fuel, and it ran for 5 minutes, so it took a while to get home again!
The car was restored 2018-2022, but not the engine. I replaced the fuel pump 10 years ago.
Today when it was around 25 degrees Celsius (77F) I drove and same thing happened again a couple of times. But I only drove maybe 10 minutes before the first stop.
Can it be something with the fuel pump? I opened the gas cap to see if it made any sound, like the tank wasn't vented. You know the pffft sound?
But if something is wrong with the fuelpump, the car wouldn't start again, would it? Is there anything I can check in the fuelpump?
Thanks!
Olle, Sweden
From what you are describing it sounds like a fuel delivery issue. Start by performing a fuel pressure and volume test. According to the
service manual, the fuel pump pressure specification is 4.0 to 5.0 psi at 900 rpm and the volume specification is 1 pint in less than 45 seconds at 900 rpm.
Your car has two "filters" which attempt to remove debris from your fuel before it enters your
carburetor. The first filter is the one in the glass bowl located in the fuel line as it makes its way from the fuel pump to the
carburetor. The second "filter" is the one that is most often overlooked and forgotten. If you have changed your fuel filter recently, yet your car still suffers from poor acceleration, your problem may be a clogged fuel screen. This screen is located behind the brass fitting which connects your fuel line to the
carburetor.
To clean your fuel screen, you first must remove the fuel line from the brass fitting. On 1955 and 1956 Thunderbird's the fuel line should go to the back of the
carburetor. Once the fuel line has been removed, unscrew the brass fitting from the body of the
carburetor. There will be a gasket attached to the brass fitting. This gasket must be reinstalled behind the brass fitting, or your car will be leaking fuel. Inside the brass fitting will be a wire screen. This is your fuel screen. You can tap it out of the brass housing. Inspect the screen for sediment buildup. Your screen can be cleaned with
carburetor cleaner. If your screen is bent or missing, you will need to order a replacement screen. Once your screen has been cleaned or replaced, reinstall the fuel screen back inside the brass housing. Reattach the brass housing to the
carburetor. Do not forget to reinstall the gasket. Once you have installed the brass housing reconnect the fuel line. If your screen was clogged, you should notice a definite improvement in your car's performance.
The gas cap on your T-Bird must be vented to allow air to enter the tank. If air cannot get into the tank vacuum will be created which can stop the flow of fuel to your engine.
Last summer, I had to replace my gas cap, and I discovered that when I removed the gas cap after running the engine for a while, I could hear the sound of air rushing into the tank. To vent the
fuel tank, the 1955 and 1956 gas caps have a rib stamped into the surface which allows air to enter from the outside edge of the cap to the center. The problem with my gas cap was that the inside diameter of the gasket was so small that it prevented the venting process.
The problem was easily fixed by removing the gasket from the gas cap and increasing the inside diameter of the gasket by cutting it with a razor blade.
doug7740
1955 Thunderbird Blue
