No fuel to carb?
My son has a 85 GMC short bed PU with a 350, and I am having an issue getting fuel to the front bowl of the carb. I have the same symptoms since the issue started, even after doing all of the below:
1. Dropped both tanks, no debris, clean as a whistle as the day it left the factory, no blockage on all 3 tubes (send, return, vent), blew compressed air through all of them in both directions.
2. replaced rubber fuel lines at tank, at change over valve, fuel pump, and at carb to chrome line with new rubber "fuel" lines.
3. replaced crossover valve
4. replaced mechanical fuel pump 3 times (stock O’Reilly, had a catch spot in pump arm movement, 2 Carters one bad, not suction, finally a good one)
5. rebuilt carb, changed out needle and seat, float moves freely, etc. for extra measure
6. I verified no vacuum pressure in tank.
7. I pulled mechanical pump, put finger on push rod, and had son turn over engine, can feel 1-1.5” of movement of fuel pump rod.
You can blow compressed air through all three lines, no blockage, regardless of side. I will pull the line before or after fuel pump, and after I blowing through lines, I can momentarily receive gas, but it stops, and does not matter which tank is selected. I have my son turn the motor over, and with the line removed after the pump, gas will shoot out initially, then stop. You can not even feel pressure. But to get it to start pumping fuel again, I have to blow through the lines. I have checked it with a gauge, and you can see it start at 6 psi, then drop to 0. Any suggestions? This is driving me crazy!!!