Hello 65ers Im having a problem with my lift pump I think.A few weeks ago I put a new ops sensor on my truck it ran fine but now its running kinda sluggish and I do not here my lift pump at all I have power at pump I have fuel comming out bleeder hose but no sound from pump.Ican start the truck and put my had on the lift pump and it feels like its running but stops as soon as you turn off the key. It does not run if you just turn key on and not start.I read the sticky and done the test but pump is less a year old and no problem until new ops.is it the ops or pump? Thanks for any help at all guys.

It sounds like your pump is running fine. They all don't make noise when they're running.

Try attaching a fuel pressure gauge to the water drain valve hose. Open the valve and you should be able to read fuel pressure. If the pump is providing pressure, both the pump and OPS are fine. You'll have to look elsewhere for your problem. How is your fuel filter? Is it cold there? Fuel treated? Additives?

I installed an electric fuel pressure gauge inside the cab. It gives great feedback on the lift pump.

Jake

Did you put Delco OPS? If not, that may be the problem.

You can jump the LP it to see if it is running and open the t-valve.
Procedure is in the FAQ in the LP thread.

Hello it is a bmd ops sensor got it at advance auto.I have always listened for the lift pump it kinda gets to be a habit with a 6-5 engine and have always heard it until now.It always ran about 5-10 seconds before start up and about the same when cut off now it does nether.Just dont want to buy something I dont need. Thanks for the help guys.

Try to exchange it with Delco OPS. Order them if necessary. Those other brand seems to not be built with the correct spec.

On 94, the LP will need the OPS to run when engine is run.