OK, where is the gas going????

I have 3x2's (Holley 94) clear fuel line running to the carbs thru banjo fittings. A stock fuel pump, and a Mr. Gasket (chrome round dial type regulator).
Engine runs fine (new build not on street yet) when I shut it off, I get air bubbles in the fuel line. More bubbles come from the regulator to the carbs than from the pump outlet to the regulator. Actually looks like the old Christmas tree lights that bubbled....really. After several hours, there will be no gas in the line from the pump to the carbs. I ran it yesterday for maybe 20 min. and tonight, the line from the regulator to the carbs is empty, but the line from the pump outlet to the regulator is full. Other times the line from the pump outlet will also be empty. No fuel is leaking inside the carbs.

I can only guess that there is a hole in the pump diaphram and it is going into the oil. But I can't detect any rise in the oil level.....but I have only had it running about 4 times. But why is there still gas in the line to the regulator tonight? I'm confused....

For what it is worth this is a '51 olds engine, stock pump.

 

does your tank sit lower than your fuel pump? if so it may be draining back to tank. if not check your oil real close it will smell like gas if it is in oil it will dilute the oil long before you will see it on the stick. good luck

 

Try pinching the line off from the tank and shutting the car off and see if it still does it.

 

My 3 deuce set up has been doing that for 15 years. It always fires up, runs good and causes no problem. I've never understood it.
The fuel pump has two one way valves that are there to prevent that from happening

 

Tank is higher than the pump, and I fogot to mention, I have a shut off valve in the line that I always keep closed when not running the engine.

 

If you didn't have clear fuel lines you wouldn't have a problem?

 

Probably normal... My buddies 34 pickup does the same... Fuel bubbles back from the carbs to the pump.. Cranks fine...

 

My quess is fuel pressure is too high. Excess pressure pushes gas thru needle valves and introduces air into the line

 

I have an OT ride that does the same damn thing and I still can't figure it out. I'll be watching this one for hints!

 

The fuel pump was bad...no bubbles after getting a rebuilt pump.

 

Just for the heck of it install a fuel pump pressure gage at the pump EXIT and see what the fuel pressure is. You may find that you really don't need a regulator.