Diagnostic Notes (Read Before Proceeding)

NOTES:
This section is used to find the correct test procedure for a given symptom. The symptoms and actions in this section are FUEL RELATED ONLY. Verify the correct system application to ensure that the vehicle has the given component.

PRE-CHECKS:
^ Check for adequate fuel supply in fuel tank. DO NOT RELY ON FUEL GAUGE!
^ Verify battery is fully charged.
^ Verify fuse/fuse link integrity.
^ Inspect all hoses, fuel lines, and connections for fuel leaks, kinks and proper routing.
^ Verify correct fuel type and quality.
^ Check TSB's for fuel system updates.

ALCOHOL-IN-FUEL
Alcohol-in-fuel can be detrimental to fuel system components and may cause driveability problems such as hesitation, lack of power, stall, no start, etc.

The problems may be due to fuel system corrosion and subsequent fuel filter plugging, deterioration of rubber components and/or air/fuel mixture leaning.

Various types and concentrations of alcohol are used in commercial fuel. Some alcohols are more detrimental to fuel system components than others.

If an excessive amount of alcohol in the fuel system is suspected as the cause of a driveability condition, test the fuel for alcohol content. SEE Alcohol in Fuel Test.

FUEL TYPES

Methyl Tertiary-Butyl Ether (MTBE)
Fuel containing Methyl Tertiary-butyl Ether (MTBE) may be used, providing there is no more than 15% alcohol by volume.

Ethanol
Fuel containing ethanol (ethyl) or grain alcohol may be used, providing there is no more than 10% ethanol alcohol by volume.

Methanol
Fuel containing methanol (methyl) or wood alcohol may be used, providing there is no more than 5% methanol by volume. Use of fuel (gasohol) that contains more than 5% methanol can corrode metal fuel system components and damage plastic and rubber parts.

THROTTLE BODY DEPOSITS
It is common for deposits to form in the throttle body and intake plenum.

Deposits on the throttle plate, and throttle bore, which reduce the minimum air flow gap, can cause idle and driveability problems, (stalling at stops, rough or unstable idle), that may or may not set a Diagnostic Trouble Code (DTC). SEE Throttle Body Minimum Air Flow Test.