We have been running our M543A2 for years with the lift pump shut off in normal driving conditions. I do not use the right hand tank on the truck, so we put the in-tank lift pump on the transfer pump switch. We turn it on for starting, especially in winter, changing filters, and really high power demands. Other than that, we can use the truck normally with the pump switched off with no problems. Given the high cost of the in-tank pumps, we figure why run them all the time when they are not needed. My son had an idea as we were finishing up the large project of getting our 5 ton dump running. He said we ought to rig the accelerator pedal with a micro switch so the in-tank pump kicks in with a certain level of pedal down-travel, which is when high fuel demand is present. To start the truck, or prime the system just push the pedal down to engage the supply pump. An indicator light on the dash will tell us when the pump is energized. We have a good supply of micro switches, so we will try the idea on the dump truck first.
Regards Marti