Vapor lock problem on a 1956

[knuckle47]

Adding all of these folks to my “Rolodex”

The first two are a simple google search. Cowboy John took and extra few tries but found him

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[CtCarGuy]

I have a simular problem whereas the car will only run on the electric. I replaced the tank, the 2 filters in front of the electric pump, the fuel line to the pump, put in a pre-tested new pump, changed the filter in the bowl and the inlet filter. I mention all of this because I have a new theory. I think the first filter (a inexpensive in-line) may be causing enough restriction to not allow the mechanical pump to pull fuel. That change is scheduled for tomorrow Also there have been a lot of bad fuel pumps being sold. I got my pre-tested one from Prestige. I know at least the vacuum portion is working. Got caught in a sudden rain storm the the old vacuum wipers worked fine.

Update: The reason the mechanical pump would not work was because of the hose. I replaced the hose to the pump when I put in the new pump. It took 3 years to figure out. Someone suggested examining the hose. The fuel line is 5/16" from the tank. The opening in the house was 3/32". I built a new hose using 5/16" fuel hose and now my mechanical works fine. I did check with the suppliers, of the 6 I wrote to, only NPD replied and said all the hoses are 3/32". I am surprised that no one else has had this problem. Hope this helps.

 

[Edwin Cassini]

I have a simular problem whereas the car will only run on the electric. I replaced the tank, the 2 filters in front of the electric pump, the fuel line to the pump, put in a pre-tested new pump, changed the filter in the bowl and the inlet filter. I mention all of this because I have a new theory. I think the first filter (a inexpensive in-line) may be causing enough restriction to not allow the mechanical pump to pull fuel. That change is scheduled for tomorrow Also there have been a lot of bad fuel pumps being sold. I got my pre-tested one from Prestige. I know at least the vacuum portion is working. Got caught in a sudden rain storm the the old vacuum wipers worked fine.

Sounds to me like you have a Vapor lock, in your Gas Tank. Are you running a Vented or unvented gas Cap.!! On this old cars always run a Vented gas cap. If you do not have one drill 3 or 4 3/32 holes through the top of Cap right on thru till you see day light !! You would be surprised to see Gas tanks crushed inword due to No venting or clogged venting. Plus Car will run faster on the Track, a Hot Rod Trick !!!

 

[paul5456]

You don't need three or four holes in the cap, one 1/8 will do .

 

[DiIanni]

In my 1955 Tbird, for years I had no problem, but within the last couple of years when the car sits in a normal garage, car starts right up.
It drives beautifully. Then when I stop the engine and if it sets in the sun on a warm day, the engine will turn over til there is no battery power left, but won't start. I make sure that I shoot starter fluid into the carb. Twice now, the following happened. A person would let me connect to their car with battery cables. Their car would run at a higher RPM, but it would not be until my engine turned over for a number of minutes and with me shooting starter fluid into the carb, would it miraculously start.
Any and all help would be helpful.

 

[CSPIDY]

In my 1955 Tbird, for years I had no problem, but within the last couple of years when the car sits in a normal garage, car starts right up.
It drives beautifully. Then when I stop the engine and if it sets in the sun on a warm day, the engine will turn over til there is no battery power left, but won't start. I make sure that I shoot starter fluid into the carb. Twice now, the following happened. A person would let me connect to their car with battery cables. Their car would run at a higher RPM, but it would not be until my engine turned over for a number of minutes and with me shooting starter fluid into the carb, would it miraculously start.
Any and all help would be helpful.

You should start a new thread for this problem

 

[Frankie the Fink]

Most likely not vapor lock, much more likely percolation/heat soak and affects MANY older cars. Here's what is happening, after a good run and you park the car in the heat, after a few minutes the underhood temperatures spike and fuel starts dribbing out of the carb "squirters" and raw fuel sits on the intake manifold runners; after about 45 minutes it'll evaporate but until that happens you will be starting a flodded car and those procedures apply. You have to hold the accelerator pedal on the floor which opens the throttle plates and the raw gas is sucked into the engine and then the car should start but will prob run rough for a minute or two. You can test this by buyiing a Harbor Frieght cheap I/R temp tun and "shoot" the carb bowls after a hot drive, any temps north of 135* or so indicates "heat soak"; in addition you may hear the fuel boiling in the carb and see the nozzles dribbling fuel down the carb bores - sure signs of the problem

 

[Ricky’s 56 tbird]

How do you correct a fuel line that vapor locks?

 

[lcboyer]

How do you correct a fuel line that vapor locks?

Move it away from exhaust manifold and tail pipes. Heat causes vapor lock

 

[SP6TIW2F]

I've run into a problem that has me scratching my head. I've rebuilt my car from the front to the rear and it has run fine for around 1,000 miles over two years. I have electronic ignition, Holley 1841 carb, 312 with auto. The other day I got about 10 miles from home driving on surface streets and all of a sudden the car started running rough. I got turned around and headed home with the car only able to run around 30 mph. At no time did it backfire just wouldn't run but if I gave it a accel pump shot the motor would pick up and then die back down. So I'm thinking that I have a fuel pump problem. I got a electric pump from CASCO so I mounted it in the body brace bracket by the front door. It would pump fuel through the stock pump (which was new at the rebuild). It this point I'm thinking I'm good. A few days later with the outside temp a few degrees warmer I started out and this time when about 15 miles on surface streets the engine started to act up the same. I switched on the electric pump and no change. The motor would still pickup with a accel pump shot but then drop back to around 30 mph. Again made it home ok. I checked the fuel filter and it was free flowing, I pulled the bowl off the Holley along with the jet plate and blew out all the passages but there seem to be nothing wrong. Checked the needle and seat, I couldn't see anything wrong. The bowl was as clean as it could be. The float level was fine. Again the new electric pump filled the bowl so it's working. The car again ran fine but I haven taken it very far. If the problem is vapor lock I wonder why the electric pump didn't help. Does anyone have any suggestions? One more thing when the car was running poorly I could rev the engine very high without any issues so I'm pretty sure the problem isn't ignition related especially when a pump shot will pick the engine up.

I had about the same problem with the Holley on my 56, the problem turned out to be the O ring on the float needle valve. The car would run fine for a few miles then it would start loosing power and then quit. The fuel bowl would overflow and fuel would shot out of the air breather tube for the float section, dumping fuel directly into the carburetor. The O ring would over a period of non use develop flat spots that allowed fuel to by pass and overfill the fuel chamber.