Falla de bom a de gasolina

Tengo una bleazer motor 4.3l 1995 automática americana: porque se baja la precion de la bomba de gasolina cuando se cambio dio 60psi en medio día de uso da 40psi y se baja a 10psi y ya no arranca el regulador esta bien podrían ayudarme llevo tres bombas que cambio en menos de un mes

comparto algunas instrucciones
Chevrolet blazer 1995 motor 4.3L
FUEL PUMP, REPLACE
1.Disconnect battery ground cable.
2.Raise and support vehicle.
3.Remove fuel tank.
4.Remove fuel pump/sender unit by turning cam lock counterclockwise.
5.Remove fuel pump/sender from tank, then pump from sender.
6.Reverse procedure to install, using new O-ring when installing fuel pump/sender unit in tank.

DIAGNOSTIC TESTS
Refer to "Fuel Injection" for diagnosis & testing procedures.
Fuel Pump Flow Test
EXCEPT LUMINA APV, SILHOUETTE, TRACKER & TRANS SPORT
1.Disconnect the EFI fuel feed line, then connect suitable hose to line and direct end into suitable container.
2.Apply battery voltage to the fuel pump test terminal. The fuel pump should supply 1/2 pint or more fuel within 15 seconds.
3.If fuel flow is below minimum, check for fuel restrictions. If there are no restrictions, check pump vacuum and/or pressure.

Chevrolet blazer 1995 motor 4.3L
DESCRIPTION
GASOLINE ENGINES
Main Pump
The electric fuel pump, Figs. 1 through 4, is attached to the fuel sending unit which is located inside the fuel tank.
Balance Pump
On 1996-97 models with dual fuel tanks, an electric solenoid fuel pump Fig. 5, is used to move fuel from the auxiliary tank to the main tank.
Whenever the fuel level in the main tank drops below 25% of the level in the auxiliary tank, the balance module energizes the balance pump relay. Pumping continues until the main fuel level is slightly higher then the auxiliary fuel level or until the auxiliary tank is empty.
DIESEL ENGINES
On all models except the 1994-95 G series, an electric solenoid fuel pump Fig. 5, is used to lift fuel from the tank to the injection pump.

Un poco mas de informacion de blazer 4.3L 1995
sensor de detonacion - diagrama ubicacion