TEST 2: Visual Inspection

How To Test A Leaking ‘Spider’ Fuel Injector Assembly (GM 4.3L, 5.0L, 5.7L)

The following test is a test I have done every time I have gotten a failed leak down test, and it involves visually checking for fuel leaks after removing the intake manifold's plenum.

Now, you might think this test step is a little overkill but I can tell you that it has saved me a lot of time by making sure where the leak is coming from (after all, I can tell you from experience that the fuel pressure regulator is not the only thing that can leak fuel).

Alright, here are the steps:

  1. 1

    After removing the upper intake manifold plenum, make sure that the ignition coil is disconnected from its electrical connector. It's important that the ignition system be disabled before continuing.

  2. 2

    Now, reconnect the fuel Lines to the ‘Spider’ fuel injector assembly (these had to be disconnected to remove the plenum).

    DO NOT RECONNECT the fuel injector's electrical connector.

  3. 3

    Now have your helper pressurize the fuel system by opening and closing the Ignition Switch several times, but without cranking the engine, as you keep your eyes on the fuel pressure regulator and the nylon fuel Lines.

  4. 4

    Once the fuel lines and the fuel injector assembly have been pressurized with fuel, you'll be able to pin-point the exact component that's leaking fuel.

Once you have identified the source of the fuel leak, the next step is to replace the part with a new one.

At the bottom of the page are my recommendations on where to buy the parts you need to replace so that you can save some money and avoid getting scalped at your local auto parts store.

Where To Buy A Fuel Pressure Gauge

You can buy a fuel pressure gauge just about anywhere. Your local auto parts store will sell you one, although at a much higher price than the one listed here on the left.

If you are in need of a fuel pressure gauge, to take advantage of the testing info in this article, the one I recommend is the: Actron CP7838 Professional Fuel Pressure Tester. This fuel pressure gauge priced reasonably and will help you with the fuel pressure leak down test.

You don't have to spend an arm and a leg on a fuel pressure gauge:

Where To Buy A CPI Spider Fuel Injector And Save $$$

If your specific vehicle has the CPI fuel injector assembly (1992-1995 4.3L V6) and the fuel pressure regulator and/or one of the fuel injectors are leaking, you've no choice but to replace the entire thing. If you buy it from your local auto parts store, it's gonna cost around or over $300 (US) -this sucks big time!

Well, if you want/need to save some money, you can buy it here:

  1. AUS Injection CP-10721 Remanufactured Central Port Fuel Injector Assembly
  2. You're also gonna' need the plenum gasket, which you can buy here: Fel-Pro MS95818 Plenum Gasket Set
  3. If the internal supply and return lines are cracked and leaking fuel, you can buy them here: Dorman 55163 HELP! CMFI Fuel Return Line

Where To Buy The CSFI Spider Injector Components And Save $$$

Below are the links to the fuel pressure regulator, individual fuel injectors and the upper intake (plenum) gaskets you'll need:

Thank You For Your Donation

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Chevrolet Vehicles:

  • Astro 4.3L
    • 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Blazer
    • 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • TrailBlazer
    • 1999, 2000, 2001

Chevrolet Vehicles:

  • C1500, C2500, C3500 Pick Up
    • 1996, 1997, 1998, 1999, 2000
  • Express Van 1500, 2500, 3500
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • G30 Van
    • 1996
  • K1500, K2500, K3500 Pick Up
    • 1996, 1997, 1998, 1999, 2000

Chevrolet Vehicles:

  • K1500, K2500 Suburban
    • 1996, 1997, 1998, 1999
  • P30 Van
    • 1996, 1997, 1998, 1999
  • S10 Blazer
    • 1994
  • S10 Pick Up
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004

Chevrolet Vehicles:

  • Silverado 1500 Pick Up
    • 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007
  • Tahoe
    • 1996, 1997, 1998, 1999, 2000

GMC Vehicles:

  • Sierra C1500, C2500, C3500
    • 1996, 1997, 1998, 1999, 2000

GMC Vehicles:

  • Suburban C1500, C2500
    • 1996, 1997, 1998, 1999
  • G3500 Van & Vandura
    • 1996
  • Jimmy & Envoy
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • K1500, K2500, K3500 Sierra
    • 1996, 1997, 1998, 1999, 2000

GMC Vehicles:

  • P3500 Van
    • 1996, 1997, 1998, 1999
  • S15 Jimmy
    • 1994
  • Safari
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

GMC Vehicles:

  • Savana Van 1500, 2500, 3500
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • Sonoma
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004

GMC Vehicles:

  • Yukon
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002

Isuzu Vehicles:

  • Hombre
    • 1997, 1998, 1999, 2000

Oldsmobile Vehicles:

  • Bravada
    • 1996, 1997, 1998, 1999, 2000, 2001

Cadillac Vehicles:

  • Escalade
    • 1999, 2000