My father in law has a 1980 Toyota Pick-up he says it has a 20R engine. He said it had a manual pump, he had an electrical pump, and now another electrical pump which he is using now(located in the engine compartment). It will only get gas to start it if the truck is parked on a hill with the tail end facing up the hill. He said either way he hears the pump cut on but it has to be on a hill like I said for it to get the gas. I don't know that much about how fuel systems work so I don't know why he has to keep the truck parked on a hill to keep gas in his line.

PS He has had this problem for awhile and has had this problem with plenty of gas in the tank.

he probably needs to install a check valve or he has a leak somewhere that allows air into the line and lets the fuel drain back into the tank

Thank you for your advice I'm gonna look online and see how much one is.