I have an 83 Class C motorhome built on an E350 Econoline with a 460ci engine. It is very slow starting when it sits a few days and I'm worried about burning up the starter. I'm told that the electric fuel pump has a low oil pressure cutoff and that it might be possible to rig a temporary override switch to facilitate starting.

Has anyone done that?

 

I would look at installing new heavier gauge cables and such along with a new higher CCA battery before I would try to by-pass something that is designed to protect your engine. Maybe something is draining the battery when it sits?

 

This sounds more like the electric pump is not running when the key is first turned on for the 10 seconds to prime the carb and the pump is only running once the key is in the start position (at lower speed because the starter has dropped battery voltage). I see an easy cure, a spring loaded bypass switch to run the pump before cranking, or better yet, fix why the pump doesn't do its short run in the key on position.