2102391 | Genuine Paccar® Fuel Pump For MX13

It supplies gasoline or diesel from the fuel tank to:

• Fuel injectors

• Carburetor (on older engines)

• High-pressure injection pump (on some diesels)

2. Maintains Proper Fuel Pressure

Engines need a specific pressure to:

• Atomize fuel correctly

• Run smoothly

• Start reliably

• Avoid stalling or hesitation

The fuel pump keeps this pressure stable.

3. Supports Engine Performance

A healthy fuel pump ensures:

• Proper power output

• Smooth acceleration

• Efficient combustion

• Good fuel economy

4. Prevents Air From Entering the Fuel System

It keeps the fuel line primed so the injectors get a steady supply.

1. Engine Hard to Start or Won’t Start

A weak pump can’t supply enough fuel pressure.

• Long cranking

• Starts only sometimes

• No start at all

2. Engine Stalling

The engine may stall:

• At idle

• While accelerating

• Randomly while driving
  This happens when the pump can’t maintain consistent fuel flow.

3. Loss of Power / Poor Acceleration

Common symptoms:

• Sluggish takeoff

• Hesitation

• Jerking or surging

• Weak high-RPM performance

The pump can’t keep up with fuel demand.

4. Low Fuel Pressure

Measured with a fuel pressure gauge.
Low pressure indicates a failing pump, clogged filter, or wiring issue.

5. Sputtering at High Speed

At highway speeds, the engine may:

• Sputter

• Misfire

• Momentarily lose power
  This is a classic failing pump symptom.

6. Whining or Loud Noise From Fuel Tank

A loud whine, hum, or buzzing inside the tank indicates:

• Worn pump motor

• Restricted fuel

• Failing bearings

7. Engine Misfires

A weak fuel supply causes cylinders to run lean, causing:

• Misfire codes

• Rough running

8. Poor Fuel Economy

Engine runs inefficiently when fuel delivery is inconsistent.

9. Check Engine Light

Common codes related to fuel pump issues:

• P0087 (Fuel Rail Pressure Too Low)

• P0089 (Fuel Pressure Performance)

• P0190–P0194 (Fuel pressure sensor range/engine performance)

10. No Sound from Fuel Pump During Key-On

Electric pumps normally make a brief humming sound when the key is turned on.
If silent, the pump or its relay/wiring may be bad.