Engine Miss And/Or Lack Of Power - keywords 6.6 6.6L cap DTC filler filter fuel loss MD no P00300 power LLY LMM water

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Engine miss and/or Lack of power possibly due to water/debris entering the fuel filler system and damaging the fuel system (filters, injectors, etc.)

Inspect for evidence of water and dirt inside the fuel tank vented cap and filler neck. If your inspection reveals water and dirt intrusion of the fuel filler neck and cap, it is possible the fuel tank(s) are ingesting water and dirt.

Now Inspect the vehicle for a possible unprotected vented fuel cap caused by a missing fuel tank fill neck collar (sugar scoop),

The purpose of this fuel fill neck collar "sugar scoop" is to aid in fuel tank filler neck mounting and direct water and dirt away from the back of the vented cap and fill neck. This reduces the chance of debris entering the fuel system as a result of tank vacuum.

Repair as necessary to provide a fuel tank fill neck collar (sugar scoop) to help prevent water and dirt intrusion at the fuel tank vented cap and fill neck

Note: GM provides upfitters and body companies the parts and the instructions for putting the fuel fillers together. The above illustration shows the Housing/collar installed at the end of the filler neck. If the fuel tank fill neck collar (sugar scoop) is not installed, this may cause damage to the vehicle fuel system.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.