Fuel Pump - Electric Dodge Dakota Shelby

INTRODUCTION

Throttle Body Injection (TBI) and Multi-Point Fuel Injection (MPFI) use 2 different types of electric fuel pumps. (Scheme 1)and (Scheme 2). Pumps are NOT interchangeable due to different operating pressures. Failure to use correct pump may cause damage to fuel system components.

TBI models use an immersible type pump with permanent magnet electric motor. A check valve, located near pump outlet, restricts fuel movement in either direction when pump is not in operation. Voltage to operate pump is supplied through Auto Shutdown (ASD) relay.

MPFI models use an immersible, positive displacement, roller vane type pump with a permanent magnet electric motor. Operating voltage is supplied through ASD relay. Pump contains 2 check valves. One valve relieves internal pump pressure and regulates maximum pump output. Second valve, located near pump outlet, restricts fuel movement in either direction when pump is not in operation.

Scheme 1

Scheme 2

FUEL SYSTEM PRESSURE RELEASE

1. Fuel pressure must be fully released before opening fuel system loop or removing any fuel carrying components. To release pressure in tank, open fuel tank cap slowly.
2. To release remaining pressure in system, disconnect 2-pin connector from fuel injector. Using jumper wire, connect injector harness terminal No. 1 to ground. Connect injector harness positive terminal No. 2 to positive battery terminal with second jumper wire. (Scheme 3)
3. DO NOT keep injector connected to positive battery terminal for more than 5 seconds. Remove jumper wires. Fuel injection system can now be opened and fuel carrying components removed as pressure is fully released.

Scheme 3

1. Release fuel pressure. Disconnect 5/16" fuel supply hose from engine. Connect Testers (C-3292 and C-4749) between fuel supply hose and engine. Install DRB-II Tester (C-4805). Place ignition switch in "RUN" position.
2. Depress ATM button on tester to activate fuel pump and pressurize system. If gauge reading is to specification, pressure is correct and no further testing is required. Reinstall fuel hose using new clamp. Tighten clamp to 10 INCH lbs. (.9 N.m).
3. If fuel pressure is less than specifications, install tester between fuel supply tube and fuel filter inlet hose. Repeat test. If pressure meets specifications, replace fuel filter. If no change is observed, gently squeeze return hose. If pressure increases, replace pressure regulator. If no change is observed, pump filter sock is plugged or fuel pump is defective.
4. If pressure is greater than specifications, remove fuel return hose near fuel tank. Connect substitute hose to body and place other end in clean container. Repeat test. If pressure is now correct, check for restricted fuel return line. If no change is observed, replace fuel pressure regulator.

FUEL PRESSURE SPECIFICATIONS

Removal (2.5L, 2.5L Turbo & 3.0L MPFI)

1. Remove fuel tank. Use hammer and brass punch to rotate lock ring counterclockwise. Disengage pump lock ring and fuel pump. (Scheme 4)
2. Partially lift fuel pump assembly out of tank until return line hose connection is visible. Disconnect fuel fitting by compressing fuel fitting ears. Discard seal and pump inlet filter.

Installation

Clean seal contact area of fuel tank. Install new "O" ring seal on pump. Install new filter on end of suction tube. Connect reservoir hose to pump assembly at suction end of pump. Position pump in tank with locking ring. To complete installation, reverse removal procedure. Start engine and check for leaks.

Scheme 4

Removal (3.9L, 5.2L & 5.9L TBI)

Remove fuel tank. Apply hand pressure to fuel pump while loosening holding clamp. (Scheme 5) Slowly release pressure. Remove fuel pump assembly from tank.

Clean seal contact area of fuel tank. Install new "O" ring seal on pump. Align fuel pump with retainer at bottom of fuel tank. Apply hand pressure to fuel pump while tightening holding clamp. To complete installation, reverse removal procedure. Start engine and check for leaks.

Scheme 5