I just replaced the seal kit on all injectors after replacing the engine in my Blazer. 4.3W. It starts and runs just fine. My problem is the pump continues to run after I turn off the engine. There is a hissing sound like air escaping coming from where the fuel lines go into the meter.
Has anyone had any experience with this? I was told It may be the relay, but where is it?

Thanks for any and all help.

I think the fuel pump relay is behind an access cover in the glove box, you may also want to check out the oil pressure sending unit- it has the ability to power the fuel pump also. Pulling the ECM-B fuse(should be under the hood) will cut all power to the fuel pump. BlazerLT probably knows exactly which relay it is, I think there are three behind glove box, but if you pull them all out and the pump still runs, that leaves only the oil pressure switch. The fuel pump is only supposed to run for a few seconds after the engine is shut off or quits running

Thanks, I found it. As I let the engine run while I filled it with antifreeze, it came out of it. I plugged it in to my scanner and read all of the parameters. It now runs perfectly.