Engine/Transmission (1994 - 1998) bad lift pump?

[Diesel Fever]

Hey guys, I am wondering about my fuel lift pump. When I manually prime it, it is fairly easy to press the boot, and when I do I hear a "sss" sound. Not sure if it's air or fuel goin in. Is this normal? Or should the boot be normally difficult to press due to being primed for the next start? My truck does take about 4-5 cranks to start normally, and barely makes it when it's 15 degrees out, plugged in, and one cycle of the grid heater (still hard startin even with 3 cycles of the grid heater). I know it should only take 1-2 cranks and should kick right over, but I'm just tryin to diagnose why, my fuel pressure gauge isn't in yet so no readings. Any help is much appreciated, Thank you.

 

[KCraft]

mine was hard starting until i replaced the over-flow valve. my old ofv came out in pieces. the new ofv fixed my issue. you might want to check it.

 

[hsmith]

Mine is not hard to push even when the filter gets full. You might try giving it a bit of throttle at starting. Shortens my crank time.