1988 k1500 fuel

[old truck dave]

1988 k1500TBI. This old goodie was sitting on a deer lease for 2 years with a busted block. Bought it, drug it home, and put a junk yard engine in it, I think a '93 350. Rebuilt the TBI ( the original TBI off the '88), new fuel injectors, regulator, new fuel pump, fuel filter, plugs, wires, rotor, cap, pretty standard stuff. Fired right up and runs great at idle. Get on the road and it craps out within 100 yards of the drive way. Have to limp it home at idle. Put MAP sensor, IAC valve, O2 sensor, water temp sensor. Still no go. Finally got around to checking fuel pressure. Cut line downstream of fuel filter and installed gauge. 2 LBS. Keep in mind, it starts and idles great. I placed a ball valve downstream of the gauge and can shut it off to check what the pump puts out before the regulator. I get 30 PSI when i deadhead the pump onto the ball valve. So I think that tells me that my pump is fine. SO I rebuilt the regulator a second time. Same crap. 2 Lbs. going into the TBI. Jumped the fuel pump to run continuously and never gets above 2 Lbs. Disconnected the return fuel line from the throttle body and turned the key on. Immediately fuel comes shooting out as if the was no regulator there at all. Just open ended. Pump volume seem fine, will fill a coffee can in about a minute. The regulator just doesn't seem to be holding back pressure so the injectors don't starve. But I've put 2 new diaphragms in and springs. I have also pinched the return  line to achieve 10+Lbs feed pressure and driven it like that. NO GO. Still craps out. Needless to say, I"M STUMPED and looking for direction

[newdude]

These TBI engines run 9-13psi.  That 2psi "downstream" of the filter, I assume you mean before the filter?  So tied into the fuel feed line from the pump to a point before the filter?  

[old truck dave]

Actually no. I tied in After the filter, between the filter (new filter) and throttle body. Reason was, that's a rubber line shielded with a cable wrap. Between the filter, and tank/pump is stainless tubing and too much trouble. I'm aware of the specs that's why it's so baffling. This morning I plugged off the return line completely and with the truck RUNNING, pump only puts out 19PSI. Remember the pump puts out about 30 PSI with the engine not running and deadheaded into a closed valve. So at idle, the injectors are sucking up 10 lbs. worth. When I put a load on, goes down to 2-3 lbs. Let up on the load, goes back to 15 to 20 LBS. This is telling me the pump is not keeping up, volume wise with what the engine is calling for. So I'm thinking NOW that even though that's a brand new fuel pump, I was given the wrong one OR it was never good from the start. I'm NOW also questioning if I got the correct injectors. But the MAIN thing about this whole situation is, why is the regulator allowing ANY gas to flow through when I've good super low inlet pressure. Especially after rebuilding it twice. If the system operates at a given pressure, that diaphragm SHOULD not unseat at all until that pressure is reached unless there is a built-in bypass of some sort that I don't know about. Thanks for the reply Senior