lift pump problems?
 

I have a 94 blazer with a 6.2/6.5 turbo diesel military hybrid. i am having a lot of issues i am trying to troubleshoot, this isuue is my lift pump not working. i first replaced the OPS, no fix, then a new lift pump, no fix, then lift pump relay, no fix. i do not get any power on the gray wire a the lift pump, the black wire does show ground. af the relay the orange wire has 12v, the black wire is ground. i do not seem to get anything from the other 3 wires. i also have a nonworking turbo and no vac. from the vacuume pump.any ideas?:scare2:

have try just putting 12v right LP see if runs better

Well for vacuum need gauge see where what working and what not working

update
 

I have traced the problem to the oil pressure sensor, i have anywhere from 8v - 11v with the lift pump pluged up, if i unplug the OPS MY VOLTAGE jumps ip to 13.5v withe the truck runningif i jumper the 12 volt input to the OPS (orange wire) to the output (gray wire) then the lift pump powers on as it should so it seems to me it has something to do with the OPS. Do I need a different switch? I have a converted 6.2 in a 6.5 blazer.

OPS is bad repalce it with acdelco

yea i know i have tried 2 new ac delco OPS
 

After 2 more hours of trying things I have finally figured it out, it turned out to be a bad pin in The OPS plug.the power feed + orange wire) had a bad connection . Until I can get anew plug I made a harness to plug up to the OPS by getting color coded wire and usingsmall spade connectors like the negative terminal on a speaker and crimping onto the wire, then cut the plug off and wired in the new jumper wires, works perfect now. I will either get a new plug tomorrow or order one if nobody has one in stock, but for now it works perfect. Tomorrow. My Heath deisel eprom, vacuum pump Eliminator, Heath Turbomaster will be in tomorrow on UPS.

glad you found the problem that is one problem that happens with ops

chalky white
 

yea the way i could tell is i looked at the terminals and two of them (tan wire abd gray wire had a nice silver look to the terminal, the orange wire, had a very ckalky white look to it could not see any Silver. then i looked at the OPS a d teo of yhe terminals were silver the termunal where the orange wire goes was black snd looked like it had been arcing a lot. thanks for your help, man am i glad that is over with. aftrr all the testing and troubleshooting plus schematic reading i feel like a 6.5 lift pump professional.:jump:

if the ops gauge in the truck is working then can the sensor still be bad? the reason im asking is because i have the same problem with mine right now. i figured that if the ops was bad then the gauge wouldnt work.

yes oil gauge can still work when the OPS goes bad

i wired up an aux switch to the pump so i can still get to work. is it gonna hurt anything if i keep driving it till payday?