So I recently swapped out engines in my 2003 silverado with a 2005 5.3 had a 5.3 before but lifters went our so decided to upgrade while I was at it. Anyway when I first fired the engine my oil pressure gauge wouldn't work just stayed at 0 so I took my turbo feed line off and manually checked it and it had 30psi at idle. Anyway I figured it was my sending unit so I replaced it and my electronic gauge worked fine for a few days and yesterday it stopped working again. Anybody have any ideas?

 

I would double check all the grounds since you did swap the engine. You could also have a short in the wiring to the oil pressure sender.

 

Yea I'll double check all my grounds but I would think that Id be having some other issues if it was a ground.