VISUAL INSPECTION
Visually inspect all electrical wiring. Look for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see the appropriate VACUUM DIAGRAMS - 6.5L DIESEL article to verify routing and connections. Inspect air induction system for possible vacuum leaks.
A-3, NO-START DIAGNOSIS
Note. For diesel information, see appropriate TESTS W/CODES - DIESEL and TESTS W/O CODES - 6.5L DIESEL article in the ENGINE PERFORMANCE section below.
- «TESTS W/CODES - 6.5L DIESEL»(ref-20088) (for C/K Pickup, Sierra Pickup, Suburban, Tahoe & Yukon)
- «TESTS W/CODES - 6.5L DIESEL»(ref-20089) (for "P" & "G" Series Van)
FUEL PUMP FLOW TEST
- Disconnect fuel line at fuel filter inlet. Disconnect fuel injection pump electric shut-off solenoid wire (Pink).
- Crank engine 15 seconds. If fuel pump does not supply about 1/2 pint of fuel in 15 seconds, go to «FUEL SYSTEM PRESSURE TEST»(ref-20091-S23117835472001010200000) .
FUEL SYSTEM PRESSURE TEST
- Turn engine off. Disconnect fuel line at inlet to fuel filter assembly. Install low pressure fuel gauge to fuel line.
- Crank or run engine 10-15 seconds. If fuel pressure is not 5.8-8.7 psi (.41-.61 kg/cm 2 ), check fuel lines and fuel tank sending unit for restriction. If fuel lines and sending unit are okay, replace fuel pump.
DIAGNOSTIC CIRCUIT CHECK
Note. For information on diagnostic system check and retrieving codes, see appropriate TESTS W/CODES - DIESEL article below.
- «TESTS W/CODES - 6.5L DIESEL»(ref-20088) (for C/K Pickup, Sierra Pickup, Suburban, Tahoe & Yukon)
- «TESTS W/CODES - 6.5L DIESEL»(ref-20089) (for "P" & "G" Series Van)
Preliminary Inspection
- Check all vacuum hoses for incorrect routing, restrictions, cuts and other damage. Inspect hoses beneath air cleaner assembly and other engine components.
- Inspect all wires in engine compartment for correct and good connections. Also check wires for pinched or chaffed spots, as well as contact with sharp edges or exhaust manifolds. (Scheme 224)- (Scheme 228).
- Perform preliminary inspection carefully and thoroughly. A thorough inspection can often identify cause of problem without further diagnosis.
Diagnostic Procedure
- Ensure all engine systems not related to Diesel Electronic Control (DEC) system are operating properly. DO NOT proceed with testing unless all problems not related to DEC system have been repaired. DEC system diagnosis should always begin with DIAGNOSTIC SYSTEM CHECK chart under DIAGNOSTIC CHARTS in the appropriate TESTS W/CODES - DIESEL article below. Performing this check determines whether DEC system and PCM are working properly. «TESTS W/CODES - 6.5L DIESEL»(ref-20088) (for C/K Pickup, Sierra Pickup, Suburban, Tahoe & Yukon) «TESTS W/CODES - 6.5L DIESEL»(ref-20089) (for "P" & "G" Series Van)
- If trouble codes (other than Code 12) are displayed, determine whether codes are hard or intermittent trouble codes. A hard code remains until code-setting condition is repaired. Hard codes cause Malfunction Indicator Light (MIL) to come on.
- An intermittent code does not reset itself and is not present when vehicle is repaired. An intermittent code is often caused by loose connections. MIL goes out 10 seconds after fault goes away.
