1993 GMC Sierra Intermittent Fuel Delivery System Problem

1993 GMC SIERRA
211,000 MILES • V8 • 2WD • AUTOMATIC
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MYSTILILAC
  • MEMBER
  • 1 POST
My husband's truck has an interesting problem. He can start the truck in the morning and all is fine. If the day turns warm or hot, the truck won't start, as well as when the engine is hot. To get it to run he has to spray Starter Fuel into the Throttle Body.

When engine won't start there is no fuel being delivered to the injectors however when it starts from the starter fluid everything works fine and engine continues to run and fuel is coming from the injectors
Jun 5, 2010 at 7:05 AM
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INTERNETMECHANIC
  • ✓Experienced Mechanic
  • 700 POSTS
Is the engine 5.7L-- gasoline? When the problem occurs, when you first turn the key on, no crank, can you hear the pump run? If not, check voltage and ground at the pump connector, engine cranking. Voltage for the pump motor is gray wire. black wire is ground. If you have good voltage and ground with no pump action, I suspect the pump.

A note, engine cranking, the pump gets battery voltage. Engine running, the pump gets alternator voltage, there is a difference. You need to use a fuel pressure gage, just to make sure about pressure. Some of the national brand auto stores used to loan out a fuel pressure gage if you don't have one. If you have TBI borrow a gage for TBI system.
Jun 5, 2010 at 8:52 AM
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