Quick Fuel Pump/Filter Question

[morethanstock66]

New O.E. style tank
New O.E. style sending unit
New carb
New fuel filter-clear
P.O. fuel pump (mechanical)-newish

Fuel filter is consistently almost completely dry upon sitting, even after running for awhile. Can a bad mech. fuel pump allow fuel to pass back through upon turning the engine off?

[Jurassic-1]

There are a couple of things to deal with. When a vehicle sits the fuel in the carb can evaporate to a point . Depending on the type of fuel your State uses I think the alcohol in the fuel will evaporate in hotter weather causing the pump to have to pick up the fuel during cranking. Some carbs like the 2-Jet or Quadrajets have filters with a built in one way valve on them . This was made to help with the pressure loss. My 1970 C-10 is not a daily driver and after sitting a few weeks needs to crank a bit to get fuel.

[morethanstock66]

I just have a fairly stock Edelbrock Performer 600. I have no problem putting an inline check-valve. I have just not had an issue in the same set up previous C10s. I think the issue is the routing. The P.O. also had modified the hard fuel line to run from the mech. pump through the gap in between the water pump and timing cover, then it becomes a rubber line, then fuel filter, then rubber line, then it runs up to carb. I am thinking the post-fuel pump route makes the line too hot, thus fuel cooking off. What do you think?

[Jurassic-1]

That is a possibility but the original lines ran pretty close and were metal. I think it could be part of the problem. Have you also checked the accelerator pump to see if you get a squirt of gas when pumped?

[morethanstock66]

I have checked after sitting for a bit and I only have left what is in the carb, if anything. The fuel filter is always almost bone dry, which leads me to believe that it drains back through after shut off. When running, it runs as if there is no issue; no gas leakage from the carb at any point. I had never heard of a full fuel line draining back into the tank either.