I've been working on my H1 for a few months now getting it back to its fighting weight. I've been noticing that the purring that comes from the fuel pump/lift pump(not sure which one purrs) has been getting louder when I'm starting up. It's noticeable while driving too. If I cold start it and turn it off before it warms up the pump makes noise for about 3 secs after the key is off too. If the truck is warmed up it won't make the noise when I shut it off, but is still loud when running.

Yesterday I half turned to the key to warm up the glow plugs like normal and I got no purring at all.... It still turned over after the wait light shut off and ran till I shut if off. I thought my neutral safety switch went out again, but that's not the case. Do I need to pick up a new fuel pump? How is it still pumping diesel into the engine if it is out? Looking for some light on this potential issue... Thanks in advance!

 

GM 15754298 is the OEM pump. SS Diesel Supply makes a good heavy duty lift pump also.

 

Thanks for the info!