no gas to fuel pump

got an 84 F150 (302) with a mechanical fuel pump. I just swapped the longblock out from a 94 fuel injected 5.0L. Yes, I took the lobe thing that bolts to the front of the cam that drives the fuel pump.

Started it a couple of times but was running rough at idle so quit for the day. Next day won't start, no fuel to carb, so replace fuel pump and tried to confirm the lobe on cam is still there. Still won't get fuel so hook up shop vac and suck fuel to pump, rehook line and start truck with help of starting fluid. Set timing but running rougher at idle on time than off time. Another story there........Truck dies and I run out of starting fluid. Charge battery again.

Day three, buy starting fluid. Won't start. No gas at carb, no gas at fuel pump, suck some with shop vac to pump, but something not right. I can blow in line at fuel pump to tank and it is clear. Have 3/4 tank in rear tank and unknown quantity of gas in front tank. If I drop the tanks, what an I looking for?

Should I run a line from gas can to fuel pump and see if that will start the engine? I'm working solo so I try not to do stupid things to blow myself up, but got to do something.

Suggestions?

No, don't bother dropping your tanks.

I had this same problem with my 77 F-250 although mine had the 460 engine (7.7 liter). My problem ended up being that the eccentric that runs the fuel pump was worn down so far that it would no longer run the mechanical fuel pump.

But in your case since you are swapping engines that is probably not the problem.

What I would do is put a block off plate over where the mechanical fuel pump goes and install an electric pump, on mine a Chevy SB block off plate fit perfectly over the 460's fuel pump hole, not sure what yours is going to need.

Thanks for the reply, but I figured it out yesterday. Dropped my rear tank, the one that my fuel gauge said had 3/4 tank gas. Turns out that the little plastic 3" piece that fits onto the end of the pickup tube came off. Also, I only had maybe 1/2 to 1 gallon of gas in it. Feel pretty stupid with no gas in the tank wondering why I'm not getting gas.

I knew the eccentric was good because I swapped it out from my old block. That was my first concern but I checked it as I replaced the fuel pump and it seemed okay. Couldn't see it but stuck a tape in and measured at different rotations.