Hello, first time poster. Hope I do everything right.

Need help with 1989 F150 with big six and 5 speed.

Due to an unfortunate heating incident it required head replacement. Cracked head. Crack was in #3 in the intake valve seat down onto interface with block.

Procured used head and lower intake manifold from junkyard. Head was tested and found to be within specs. Reassembled engine with no obvoious problems.

Cranked engine up. Ran like crap for first minute or two. Probably was hitting on 3. Eventually you could hear two more pick up. But one was still missing.

Proceeded to pulling spark plug wires. It was found that #1 was not hitting at all. Proceeded with usual spark check. Definite spark plug firing was seen. Even swapped sparkers from #1 and #2 cylinder with no results. Checked compression on #1 cylinder it seems to be OK. Tore engine back down to valve cover. Pushrods in good shape and rocker arms seen to be moving when engine cranked.

So now this thing runs great on 5. Starts right up and drives OK but #1 will NOT FIRE! I took wiring harness off of fuel rail. 13.5 V power seen on red side of injector clips. The #1, #3, and #5 injectors show continuitiy on yellow wire side of injector and #2, #4, and #6 show continuity on a separate circuit. So that seems to be in line with what book shows in wiring diagram.

Am quessing that it is a fuel problem. How to check the injector on #1? Just swap them from hole to hole? Probably going to check that next. I suppose I'll get some new sparkers too, it needs them anyway.

Any suggestions appreciated. Sorry this is so long. Trying to be quick and still get all important details. THANKS.