93 Lift Pump no voltage??

[ewordal]

My 1993 K2500 blew smoke and missed when I sterted it up there other day. Almost acted like it was running out of fuel. So I thought I would replace the fuel filter, because it had been a while. The filter was dirty, but not too bad. After I changed the filter I went to turn the key to refill the fuel pump canister and the pump did not run. Then I jumped the fuse that is on the firewall for the fuel pump and the pum ran and the canister filled up. I started the truck up and it was missing and smoking still, so I tried jumping the fuse for the pump again, and it smoothed out. It seems to me that the pump is not getting voltage. I have not had a chance to drive it yet, but I was just wondering if anyone has had the same kind of problem and what they did to fix it? Thanks, Erik

[Hubert]

Lots of threads and posts on oil pressure switch going bad causing that. I'd look at that. Its a safety circuit for IF you are in a wreck and motor cuts off; there won't be any oil pressure so it cuts the fuel pump off - so fuel won't be pumping with the key still on run.

[Turbo Al]

Hurbert has given you the correct info, in a pinch you can also "hot wire" the connector that leads into the oil pressure switch but you are BYPASSING and important safety system.
AL

[Kennedy]

While it's not an inexpensive product, I have a lift pump control harness that eliminates issues and adds a couple of neat features like a timed "prime" at key up and manual override for bleeding filters.

[HowieE]

If as you said you jumpered the fuse and the problem was corrected I would go back and check the contacts in the fuse block and the condition of the tabs on the fuse. The fuse is before the oil pressure switch and jumpering it should have no effect on the operation of the OPS.
The OPS circuit is shown on my web page along with the modification to reduce the current across the OPS. You will see the relationship there.
http://mysite.verizon.net/vze54tx9/id13.html