fuel system trouble

[staggerd86c-10]

this was a challenging weekend, I finally got the a/c working again(partially, ill get to that in a min.) but the truck was mis-firing and i didnt know where the hell it was coming from so i started by changing out the spark plugs then checking the cap and rotor ended up buying an msd hei distributor. all said and done still there. It seemed like maybe it wasnt getting enough fuel but my holley mech. pump is rated way before what i need, so im not sure what i need to do. i changed the fuel line going to the carb and put one that i can put a guage to make sure its getting pressure. i took it out for a ride and the truck ran out of gas again. i thought maybe its the valve that switches the tanks so i bypassed that was running good but once i got on it the truck falls on its face again. I'm not sure what it is thats making it do this but i have narrowed it down that its in between the gas and the pump because the pump to the motor i ended up putting everything new. please let me know what you think. please.

[us111]

hello,certainly could be a fuel filter,but i'm leaning more toward
carb prob.i only say this because i had just about same
problem,got tired of fooling around,put new carb on and belive me,
it don't fall on it's face anymore.lol

[staggerd86c-10]

yeah but the guage on the fuel line says it has no pressure. so it has to be before the fuel pump. i dont know im completely stumped.

[454HO]

Could be vapor lock. Is the fuel line close to the exhaust anywhere? If the fuel in the line vaporizes, the fuel pump will not work. It is designed to pump liquids, not vapor.

[andresco50]

Check the fuel pump or the fuel level sending unit have a filter maybe is covered with dust or something.. the carb filter, or the float assy is damaged.. clean the carb too!!

[staggerd86c-10]

i think it may be the pick-up in the tanks im going to drop the tanks and see if anything is messed up in there and get rid of the dirt that has accumulated for last 22 years. I think its vapor-lock but i checked all the lines and its not really getting all that hot around them or are they near any exhaust. Thanks for the suggestions guys.

[Captkaos]

If you unplug the line to the carb can you pump gas out of it? Put a glass jar and pump it into.

[piecesparts]

Does this do this ALL of the time or just when you drive around city streets? The comment about vapor lock is a possibility---I put on a new Edelbrock Street fuel pump and experienced the same type of performance on a new engine. With the stock fuel pump, the problem did not exist. I know that my original fuel pump had the return line built into it and that when I used the Edelbrock it was plugged off, it was letting the fuel overheat in the fuel pump and vapor locking the supply to the carb. I put on one of Edelbrock's bottom plate adapters and added a small orificed return connection back to the tank and WAAALAAA the problem went away.