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1994 GMC Jimmy Base 2dr

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January 3, 2010, 2:17 pm

AutomotiveForums M

Question: Can anyone help?

My 1999 Gmc Jimmy while driving lost power.
Now runs rough and throws a P0300.
Don't know where to start.
Someone said it is a possible head gasket.
I don't have any coolant in the oil.
It has a 4.3 vortec 135,000 miles

January 11, 2010, 9:38 pm

AutomotiveForums M

i HAVE THE exact same problem.. p 0300 mine is nlowing black smoke out tail pipe, and backfires. though.. does yours?
Anyways. i first replaced my fuel regulator and the crappy fuel injectors they used stock that leak... and no go... so I am looking at wether or not i have JUMPED TIME>>> you may have a worn timing chain?

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January 11, 2010, 9:41 pm

AutomotiveForums M

Oh by the way. Its not your head gasket, if there is no coolant in the oil : )
Start with the easy stuff first, Spark plugs, wires, cap, rotor, GOOD LUCK

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