I installed an inline Walbro fuel pump. 2 days ago the engine fired for the 1st time and it had good pressure. Since then, I can't seem to get any fuel pressure. I will check the lines. Where are rubber fuel lines on the car? between hardlines and tank? Considering the 84Z28 I'm swapping the Lt1 into was origionally carbed, should I be concerned about the in-tank sending unit not allowing the pump to draw fuel?

 

Did you pull the old pump out? Is the sock messed up in the tank?

Yes there are rubber lines between the sending unit and the body hard lines.

 

UPDATE

I think I have finally fixed the problem. I replaced my Walbro 255 lph inline pump with an intank pump. I changed the tank to a fuel injected tank (for the baffles), but I don't think a car that was origionally carb'd would have to swap tanks. I put a new Bosch in-tank pump in and wired everything back up. No stalling. I think the issues was 2 fold. 1st was the inline setup. I was having cavitation and vapor lock. The gas does get heated in the return style system in the LT1. Having an inline pump places the fuel under vacuum. When under vacuum, it lowers the boiling point of the gas causing fuel to boil in the line prior to the fuel pump (cavitation). Since the fuel also lubricates the fuel pump, the bubbles from boiling would allow the pump tp heat up and make the effect worse. Once this process started, it would become a downward spiral.

The 2nd part was the fuel pressure regulator. I replaced the on rail regulator with a spare I had and now it runs much better. I am still having hard starts, but I think that is because the "newer" FPR is better than the other, but not 100%. I also noted that after a 30-45 min drive, it would bog down at WOT and not spin the tires. While this still needs addressed, it is not needed for daily driving. I have been driving it now for 3 days to and from work (22 miles each way) plenty of time to heat up and have been in bumper-to-bumper traffic for upwards of 30 mins, still with no problems. I ordered an on-rail FPR from Aeromotive and that should completely fix the entire situation.