How do I test for/ diagnose that? Wait a second! That may not be the Carter pump I put on it originally. That maybe some junk from advance auto... when I got the body, it was supposed to be a lot of things it Wasn't, so had issues w/ fuel delivery until I replaced tank, sender, and did a 3/8 line upgrade. Damn things looked like a rotted / clogged cast iron sewer line! But that was over a year ago