Fuel pump issue?

[The docdoc]

My 1996 Explorer XLT 4.0 liter has started an intermittent problem. A couple times recently when I go to start truck it cranks without starting. Fuel pump or relay possibly? Since I bought the truck two years ago for a hunting vehicle, I noticed when the ignition is turned on half way you can hear a hum from engine that sounds like a pump coming on. I also noticed that when it cranks and does not start, that sound is missing. Any help in trouble shooting is greatly appreciated!
Thanks from a newbie

The docdoc

 

[Rick]

Sounds like you have it narrowed down to the relay or the fuel pump. You can swap relays in the power distribution box to see if the problem goes away, or transfers to another circuit when you do the swap.

If it's not that, it's the fuel pump. It's a common problem on 100k+ Explorers.

 

[The docdoc]

Thanks for the reply. After being stumped for awhile over the fact that it was intermittent, I saw a trick on you tube about pulling relay and using copper wire to bypass, fuel pump kicked on (thank God). There was an issue with ground wire under power box. Had same problem a while back with a/c blower not coming on (intermittent then failing), the issue was a ground wire under power box. To that I tried new relay, console switch, blower resistor to no avail. I would encourage anyone with an older Explorer to check that first with similar issues because it seems that with age, mines a 96' with over 200k, I have encountered bad grounds that were the cause of the problems.