Putting a fuel filter on the inlet side of the mechanical pump might solve the problem, if indeed it's debris from the tank causing the pump to malfunction intermittently, but make it a BIG filter so there's minimum restriction. I like to use the big Ford fuel injection system filter that's about 3" in diameter, with a steel canister. Hide it under the cab near the fuel tank outlet- - - -out of sight, out of mind!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!