I have a 99 k2500 hd 5.7 vortec. It's the older body style not a Silverado. It has an issue where you have to let it run a minute before driving it or it will cut out while accelerating. Also it cuts out if you try to go wide open throttle so I figure fuel pressure may be low so I am changing fuel pumps. When I took the bed off I noticed it has 2 places for electrical plugs but only one was connected. I have pics showing this. Why is there no plug for the second spot?? I know it's a fuel pressure sensor of some sort so why is it not connected to anything? Also I noticed replacement fuel pumps have a flat plug with the 4 pins in a straight line instead of like factory with a cube type with 2 pins on top and 2 below..why? Any help would be appreciated!

 

1) The other sensor is the fuel tank pressure sensor. Depending on the original options for your truck, it may not have been equipped with one from the factory, but many aftermarket pumps have them already installed. A PO could’ve changed the pump and installed that one even though there’s no harness plug for it - or, the plug was damaged and the PO cut it off and taped up the wires inside the harness. It’s primary function is for the PCM to detect flow during EVAP system purging, so if the truck’s charcoal canister, purge and vent valve are still present and functional, open the harness loom to see if the wiring is there. Replacement plugs are available.

2) The 4 flat connector on your replacement pump is an upgrade from the original square connector. The new pump should have had either a pigtail to splice in or adapter included.