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kawinj

kawinj 3/2/2011

1999 GMC Sierra 2500 SL 8 Cyl 6.0L

Engine

Starts great cold. After warmed up, restarts very hard, with bucking.

Fuel pump/sending unit replaced in 03 after being stranded three times. After that truck drove fine every day up till 07 when I got a new van (daily vehicle)
Truck sits a lot now, maybe driven seven times a month.
o2 sensor replaced three days ago. No change. Still fires up instantly in the morning, but after making a few stops during the day ie: store, bank, etc. It cranks but needs the gas pedal pumped a couple times, then starts and runs at very low rpm and bucks almost at the point of stalling. Within a minute it climbs back up and runs normal.
I have been running a higher octane gas as well.
EGR valve?
Another fuel pump assembly?
Fuel injectors?
Never had a complete tune-up. original spark plugs
Fuel filter was changed last year.
Semi-mechanical here (carpenter)

1 Answer


J and K AUTOMOTIVE TOWING AND REPAIR

is there a check engine light on?

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J and K AUTOMOTIVE TOWING AND REPAIR

kawinj 3/2/2011

Yes, before the o2 sensor was replaced. Now it's off. The code was telling them that was the problem. Any suggestions much appreciated.

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