This one has me stumped...I have a 65 Riviera...the guy I got it from said he had a carb rebuilt and put it on ...it runs like it is dumping raw fuel into the carb. The first carb he had on it same problem. He took the tank out cleaned it and coated it, cleaned the sending unit. Black smoke chugs out the tailpipe. I bought a Edelbrock carb...used...and put it on...same thing...gas will start overflowing from the top of the carb. I thought maybe floats hanging up or too rich...took the top off the carb adjusted the floats leaner...same thing. It will run for a few seconds then start chugging because gas is coming out of the vent tubes. Bought a cheap pressure regulator and that seemed to cure it...I bought a new fuel pump (original mechanical style) and replaced it...thinking maybe something was wrong internally with the fuel pump and it was pumping out more pressure than it was supposed to. Hooked it all up...same thing! This system has a vent hose that comes off the fuel filter..before I hooked it all up I blew through the hose and it seemed open and it is connected to the tank like it is supposed to be. So there is the problem...too much fuel pressure...now three different carbs flooding out. Tank is clean...sending unit is supposedly clean, new fuel pump...any ideas?? Thanks guys!

first take that extra line from fuel filter and put it in a container. see how it runs. if runs good, did you just check it by mouth blowing through or compressed air? also reconnect if running good and take off gas cap. somewhere or someone put a non vented gas cap on it. where that car will take a vented cap.hope this will get you in right direction.

Bill...I blew through it with my mouth...the gas cap isnt even on the tank! Could it be the hot air circulating passages under the carb that are on the intake...maybe a wrong gasket or something? It is truly weird...

put that extra hose into a container and see what hapens. we will go from there.

Hi all...well I solved the problem....I ran the car on a boat gas tank I have and it did the same thing as above..so clearly it wasnt a fuel pressure problem. Pulled the carb off and saw that the intake had a heat passage that runs under the carb (afb) that had a lot of carbon residue. So either the intake had a crack or something in the head was screwed up...I put expansion plugs in the holes on each side of the carb then put JB weld over the plugs. I ran a steel shim carb gasket and problem was solved...pretty weird...thanks for the advice!