idle problem and fuel priming problem

[chevy4ever]

Hey guys.. I got two issues going on at the moment. Both ive been fooiling with for over a month now.Its on my 90 burb with 350 tbi For one my fuel pump wont prime. My understanding is when the key is in the "RUN" or "START" position it should send a signal to pump to prime for 5 seconds, then shut off. Once the oil pressure builds up the oil pressure sending unit takes over and it maintains the fuel pump. Well im not getting the prime signal to pump. Ive replaced relay, ecm and fuelpump.i wasnt getting the relay to kick on with old ecm. Now i get the relay coming on but it doesnt get the signal to pump. Now if i run a HOT wire to the grey wire at fuel pump relays harness (the wire that runs to pump) it kicks on pump. I was thinking i would run a toggle to prime it manually but when i do that it pops the ECMB fuse and it wants to start up like a carb...like having to warm it up. The pins on the harness all look clean and look like they make good contact with relays pins. I really am getting kinda stumped on this.

Also my idling problem. 350tbi
Basically my idle starting acting up about a month ago or so im pretty sure its non related to the priming problem.If im sitting in drive waitin at a light my idle with bounce and will sometimes shut off the truck. It seems like it comes and goes. Happens alot after im on the gas more. If i pull a vacum line loose, it will raise idle and run a bit better but you can still tell its rough. Once im on the gas it runs great. I changed out the EGR solenoid, pvc valve. I put on a new MAP sensor to see if it changed the way it ran but it didnt fix the problem so i put old one back on. I took off the EGR valve and cleaned it with carb cleaner. I also took off the idle air control valve and clean it. This seemed like it made it run slightly better as far as on the gas, but it still has same idle problem. Both injectors are spraying nice and even. I have no codes. Has new wires, plugs, coil, dist cap and rotor.all new vacuum lines. This motor is a new rebuild about a year ago. Kept all old componets so parts like egr valve, egr solenoid,tps are orig 19 yr old.

I could really use your guys help on this. If any one has any ideas please... let me know.

Thanks guys... by the way... this board is the best ive ever been on.

[N2TRUX]

I'm moving this to the main 73-87 truck forum. I think you will get a better response there.