Alrighty all, I’m off tomorrow and I’m going to figure this out. Wanted some advice or direction if I’m missing something. 88’ 460 EFI builds pressure runs at 32-36~ at idle. Jumps to 40 when snapping the throttle. It will randomly lose pressure and die. It will sit and idle with me revving it up or every once in a while for 45 minutes with no problem 98% of the time. The second I leave the drive way it loses pressure and dies every time. Sometimes it’ll take 5 minutes to build pressure, sometimes it’s immediately. If I’m driving it always goes to 0psi if it happens in the driveway it drops to 20ish. Fuel regulator is new last week. It was pissing fuel out the vacuum port. I also replaced all the vacuum lines. Relay seems fine. I did open the Ecm and it’s spotless, no leaky caps, no heating that I can see. Front pump is 1.5 years old (went bad already). Rear tank pump is new as of January/February when I took the bed off and cleaned the tank. HPFP was changed when I did the front tank. Fuel selector valve will be here tomorrow. I know it’s bad because I gain fuel in the front tank when running from the rear tank. I’m probably going to lift the bed so I can maneuver from pump to pump a little easier. I plan on disconnecting the fuel lines and running each pump separately to see if I can replicate loss of fuel from the rear tank pump. If not I’ll swap out the HPFP with the Bosch I have on the shelf. Am I missing something?

 

The internia switch is also bypassed.