I just purchased a 1994 Chevy C2500 6.5L. When I got it home, I was doing some things like radiator flush, fuel filter, etc. I changed the fuel filter and apparently got air in the lines. I followed a procedure I read online to crack the bleed valve at the top of the filter and jump the fuel lift pump fuse to the bus bar on the firewall to actuate the lift pump. I waited until I saw fuel flowing from the bleed valve. I also changed the lift pump suspecting that it was the culprit causing the hard starting problem I was having. It seemed to take an longer-than-usual number of revolutions to crank the engine, and when the engine was warm, it took even longer. When I got under the truck to change the lift pump, I noticed that the previous owner had clipped one of the wires coming from the pump and wired it directly to a positive connection so that the pump was getting power all the time when the key was switched on. I changed the pump, connecting the new pump plug as it should have been. I jumped the relay fuse to the positive and the pump actuated. I have also opened the bleed valve on top of the filter and fuel comes out while cranking. So I bled the filter valve. I opened the t-valve at the front of the engine and forgot and left it open. I was able to start the engine right up. Then engine idled very smooth for a couple minutes. I realized that I had left the t-valve open and turned it off. The engine almost immediately died. I have gone through several cycles of bleeding the filter, which no air comes out any longer, and the t-valve. I am getting fuel from both with no air. I loosened three of the fuel lines to the injectors on the left side of the truck and cranked until I saw fuel seep out. It was spraying out. I disconnected one of the lines to the #1 injector completely and cranked until fuel dripped out. I tighten the lines and cranked for a few seconds. The engine started and ran for about 15-20 seconds before shutting off. I am again back to the place where the engine will crank and crank but will not start.

 

Your LP was most likely direct wired because your OPS is bad.

Hard hot starts are usually a sign that your IP is taking a dump.

As for your air problem: Is it possible you cracked a line during the LP install? Is your filter seated in properly? Try cracking just one injector line to purge.

 

I replaced the LP and plugged in the plug the way it should be. I got fuel from the t-valve while the engine was cranking. The filter is seated properly and no line was cracked. The engine did start once and ran for about 5 to 10 seconds before shutting off. Completely disconnected one fuel line, but the fuel just dripped while cranking. Should there not be a lot more flow or pressure while cranking? This is my means of transportation, and I spent my last dime on the filter and pump. The engine was running before, but now the truck is sitting in my driveway and I am taking a taxi or catching a ride and walking the rest of the way.

 

As stated the LP is powered by the oil pressure switch while the engine is running-yours appears to need a new OPS and you should also google and install the "OPS relay mod".

The LP is powered by the LP relay during cranking and OPS takes over when the engine is running.