Fuel Pump Issue?
Thank you guys for the input. Items I forgot to include: Tank and sending unit are both new, all rubber lines were replaced, I also cleaned the steel line using brake clean then blowing it out before installing everything, fuel pump was replaced week. Still having the same issue with the new pump.
What type and how many clamps are installed on the New neoprene rubber jumper at the back, from the sender to the main line?
If this jumper sucks air, you will get exactly what you describe. Because this jumper is higher than the tank, it does Not leak liquid fuel.
If gearclamps, you need two on each side, staggered 180 degrees and as close together as possible, and NOT overtightened. This to squeeze shut the tiny gap that usually forms right next to the screw of the first clamp.
If factory spring clamps are used, the fuel line must be properly sized for them, then one per side will be enough.
Make absolutely sure that NONE of your rubber jumpers are kinked. The kink, under suction, will cause the fuel to boil right there due to the vacuum that the pump is creating. By the time it gets to the carb, it should have returned to liquid form. But if the kink is severe, you could end up with a 5/16ths line full of vapor from pump to tank, and the pump cannot pump vapor. When this happens the little return spring on the pump-arm, does not return the arm ready for the eccentric to stroke it again. So the arm just flops around a bit.
After the engine quits running, the check valves in the pump, seal the line there. And so the vacuum still in the line, continues to tug on the fuel sender, and syphons fuel up the line until the vacuum dissipates which simultaneously allows the vapor to condense back into fuel. Since the lowest point in this line is usually very close to the pump, on the next cold-start, the pump easily purges whatever vapor might remain, and pumps the fuel behind it, filling your filter with a bit of a bubble, which just sits there in the high point of the horizontal line. But fuel gets by on the low side, and eventually the fuel bowl fills up. Then off you drive...... until the cycle repeats.