So, fuel system testing, always starts, by just listening.

First, turn the ignition key, to the run position and carefully listen.

Consequently, there should be a slight humming sound, coming from the fuel tank. This humming sound, should continue, for approximately 2 seconds before stopping.

Actually, fuel system testing, has already started. When this humming sound is heard, it can usually be assumed that; the fuel pump electrical circuit, is functioning and that, the fuel pump is running.

The next diagnostic steps should include:

  • Is there is an adequate amount of fuel in the fuel tank.
  • Testing for fuel pressure and volume.

But, if the humming sound was not heard; then the next fuel system testing steps, should include:

  • Verifying the lack of any fuel pressure, with a fuel gauge or scan tool.
  • Checking the fuel pump electrical circuit.

Fuel System Testing, Common Fuel Delivery Systems

So, the (PCM) commands the fuel pump, to apply 35-65 psi of fuel pressure to the injectors. Consequently, by grounding the primary fuel pump relay circuit.

One And Two Line Fuel Delivery Systems:

  • On two-line fuel delivery systems. So, an external vacuum-modulated fuel pressure regulator, controls the fuel pressure. Consequently, The two-line fuel delivery system, returns excess fuel to the tank using a return line.
  • In contrast, on a single-line fuel delivery systems. So, an internal non-modulated fuel pressure regulator; in the fuel pump module, controls the fuel pressure. But, the single-line fuel delivery system, uses the same line.

Finally, most conventional fuel delivery systems include, a Schrader valve, at the fuel injector rail. Furthermore, allowing for, mechanical fuel pressure testing.

Choose Your Fuel System Testing Help Topic Below

Fuel Leak – If You Smell Fuel This Could Be A Sign Of A Fuel Leak

Fuel System Related Problems – Not Always Easy To Solve

Mechanical Fuel Pumps – Basic Information And Troubleshooting

Fuel Pressure Regulator – FAQ – Do You Have The Correct Pressure

Fuel Pump Issues – Excessive Heat – Contamination From Dirt and Rust

Engine Fuel System Testing – Proper Testing With Solutions

Fuel Pressure Regulators – Function, Failure Symptoms And Testing

Automatic Shutdown (ASD) Relay – Function – Failure – Testing

Fuel Pump Relay – Function And Testing Procedures

Noid Light – How To Test Fuel Injectors Using A Noid Light

Fuel Wash – How To Eliminate This Potentially Serious Problem

Fuel Injectors – Will Usually Only Fail In One Of Three Ways

Gas Getting Into Oil – What Can Cause This To Happen ?

Fuel Pressure Regulator – FAQ – Do You Have The Correct Pressure

Common Fuel Pump Related No Start Problems – What Should You Check

Fuel Getting Into Engine Oil – Causing Premature Wear Of Engine Parts

Thank You !