Buick Repair Questions? Ask a Mechanic for Answers ASAP
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possible causes are
1. low fuel pressure. I would check the fuel pressure. you can rent a tester at a parts store if you dont have one
2. possible clogged cat converter.
3. egr valve open. it would set a code.
4. timing. worn timing chain
it is possible but not likely. there are bypasses in the filter for when it gets clogged
replace the fuel pump assembly
egr 180 plus 1 hour in labor
pump is about 250 plus 3 hours in labor
converter, yes you have one, 350 plus 1.5 hours in labor
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