My awesome 1996 Blazer has been a GREAT vehicle. It looks great and has run great (314,000 miles - original motor) and gets good mileage (22-24 highway).

Several months ago, I took it in for a maintenance tune up.
Immediately, it started running poorly, noticeable black exhaust and getting really bad mileage (10 per gallon).

I took it back to the mechanic. He replaced the fuseable link and the battery.

Still ran bad...more smoke. He said that it was just getting old.

Took it to another mechanic. He checked the plugs and they were fouled. They were replaced and a new o2 sensor added and also an ERG valve.

Runs just as poorly.

Sluggish, no power, struggles going up hills, high RPM....and 8 miles per gallon.

I know that she's old...but she was running fine before the tune up.

I read something online about a "Safe Mode" and am wondering if my computer wasn't reset properly when the work was done or ???

Any advice would be so appreciated. I really wanted to see if she could make it to 400,000. She was well on her way.

Thank you!

 

Have you tried unhooking the battery? Although it sounds like you have a fuel problem. Black smoke meens its running rich. You should do a fuel pressure and leakdown test.

 

no codes huh? i would go with 50lb cat's advice. sounds like a fuel issue especially considering the plugs fouled out so quickly

 

Fuel pressure regulator or spider & injectors possible. But I agree a fuel issue.

 

Check you plug wire routing and that all wires are seated properly on the cap and plugs.

 

Was the tuneup done with Delco parts - plugs, wires, cap & rotor?
These things hate anything but original equipment when it comes to tuneups.