My 57 Special has a glass bowl filter and for some time I could see a few air bubbles in the fuel while the engine was running but it ran OK. At a small show last week the damn car died on me. It was very hot and the fuel in the bowl was full of air bubbles. When it cooled down it ran but still had air bubbles in the fuel. Everyone guessed vapor lock.
I got it home but could not get rid of the bubbles when it got hot.
I found the problem yesterday. Do any of you detectives out there want to offer their ideas on what the problem was.
The clues.......

Single stage fuel pump
Rubber fuel line from tank to pump, no filter in line.
Rubber hose from pressure side of pump to glass bowl filter.
Ran OK when engine cold, some bubbles when warm, much bubbles and fuel starvation when hot.
NO evidence of leaks and no smell of gas anywhere.

Bob,

I'm wondering if the pump could be sucking air on the vacuum side.

Howard

Yes it was Howard but I could not find where. The fuel hoses are new, and I reclamped all the connections, it made no difference. There was no fuel in the oil but I decided that somehow the diaphram was leaking air. I pulled and disassembled the pump. The diaphram was like new, Indeed the pump is only a few years old with few miles on it.
The suction side of the pump is a 5/16 ell tube. It appears the tube was either cast with or pressed into the casting. For no good reason I tried wiggling it and I could feel the slightest loosness. A few twists by hand and it pulled right out of the casting.
When the pump got hot the casting expanded enough to allow air to be sucked around the tube and into the gas stream but it was tight enough to never leak gas.
I tried soldering the tube in place but the casting material wouldn't solder so I opened the hole and tapped it out to accept a 1/8-27 pipe fitting. I reassembled the pump and it's now fine.
What a wierd problem.....Bob

Thanks for posting this. I'm checking my 56 tomorrow.

In my case the car runs fine, but I never see any fuel in the in line filter I installed. I used to see half full filter but in the last year I see no fuel but the car still runs okay?

Weird is right.

You're most welcome John. I posted it hoping it could help someone, and not to say "I'm so smart". I did find the problem only by a lucky twist of the inlet pipe........Bob

I think you're pretty smart, you knew where to look. And you're a good Buick guy too. Not everyone would post something like this. But, posting something like this is what makes this site very valuable. I have always been intrigued by why my fuel filter looked empty and still the car ran okay. I can't wait for the remnants of Hanna to depart so I can check if this is is the answer.

Bob,
I think this might be a cool new category. Detective threads. We all know you're smart, you certainly wouldn't need to call attention to it .

Mike