1996 GMC Sierra third cylinder misfire

Tiny
AWORLD50
  • MEMBER
  • 1996 GMC SIERRA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 248,000 MILES
I a 1996 gmc sierra pickup 248000 miles The troble code reads third cylinder misfire. When you start the truck the check engine light stays on. But when you let it sit an idle for 15- 20 minutes the check engine light starts to flash. What do you think could be the problem I have had it tuned up and no results still the same problem
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Monday, March 9th, 2009 AT 6:07 AM

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Tiny
JACK42
  • MEMBER
96 has CPI injection, they had big problems with the injectors in those. Be sure it has good compression and strong spark, if so the injector is usually the problem. If new plugs were just installed, pull #3 and any other and compare them to see the color difference. Does it use any coolant? If so have the cooling system chemical tested for exhaust gasses (blown head gasket)
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Monday, March 9th, 2009 AT 8:05 AM

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