sun20ma

I have a pro flo xt efi on 65 vette and I am losing full pressure after shuting down in less than 4 hours Any help

63split63

More info is needed . Will the engine not start ?

sun20ma

I have to cycle key first so pressure goes back to 40 After I shut it down in less than 4 hrs it goes to nothing If I start it in less than 2hrs it is fine

AZDoug

Bad injector or check valve in pump isn't sealing. Possibly the regulator, depending on how it is plumbed.

Doug

bosshog8

I would agree with this but expect to see a huge plume of black smoke if it was an injector. If it's easy enough to plug the return line and build pressure you can possibly determine which it is. I would suspect the pump first.