2002 GMC C1500 Will not run

Tiny
HOLOGRAM_16
  • MEMBER
  • 2002 GMC C1500
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 76,000 MILES
4.3L V6, was having problems with vehicle idling too low (enough to stall) while in gear at a stop. I've replaced the fuel filter, all spark plugs (w/ proper spacing), replaced air filter and replaced the IAC valve sensor. Also cleaned out the top of the throttle body. All of these replacements were done at the same time without attempting to start in beween. The truck will not start now. The engine turns, but will not turnover. No codes registering on the computer. The fuel pump was replaced this January at somewherer around 70,000-72,000 miles. Battery is a Optima Deep Cycle (yellow top) installed last Jan or Feb. Also, during attempts to start the engine seems to lock up or fail to continue to turn (hit and miss). My next guess is timing belt? Any help would be helpful.
Sunday, June 21st, 2009 AT 4:33 PM

4 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The truck will not start now.

Do below and come back with some results we start here-

Disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, cap and rotor /distributor pick-up coil, ignition control module, ECM, Ignitor cam and crank sensors- Note: If it doesn't apply disregard it

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time/broken or jumped timing belt/chain
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Sunday, June 21st, 2009 AT 4:44 PM
Tiny
HOLOGRAM_16
  • MEMBER
  • 3 POSTS
Spark plugs firing properly (blue spark). Fuel pressure at the valve prior to the injectors is reading 60psi when turning key to on position drops to 50 psi when turning key to off position.

The book says to use a stethoscope to listen to the injectors when the engine is running, but I don't have a stethoscope (or know how to use one) and the engine obviously isnt running. Is there another way? I can say that I can smell gasoline coming from the throttle body after attempting to start multiple times. Does that count?

"troubleshoot the ignition system" - Is this something I would need a diagnostics system for?
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Monday, June 22nd, 2009 AT 12:15 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Use a long screwdriver as a listening device on the TBI unit if its clicking while cranking it over or look at the injector/s if its squirting fuel.

I can say that I can smell gasoline coming from the throttle body after attempting to start multiple times. It can have fuel but if the presssure is wrong it won't start.
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Monday, June 22nd, 2009 AT 4:50 PM
Tiny
HOLOGRAM_16
  • MEMBER
  • 3 POSTS
Ended up taking the vehicle into a mechanic. Issue ended up being a corroded distributer cap and rotor (both green in color). Mechanic replace the cap, rotor, and plug wires. Vehicle runs like it is bran new now.
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Monday, July 6th, 2009 AT 12:22 PM

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