infamous

Hello everyone, i recently bought a 1995 chevy Blazer, and i have been having some troubles with it. First off, it backfires and sets off an engine code. Seccondly, its VERY heavy on fuel; probablly 100km/full tank. The blazer has a 4.3 L vortex, if that helps. If i disconnect the battery to clear the codes, it runs good for about 5 minutes, then service engine light returns. Any advice would be appriciated. Thanks in advance.
-Infamous.

golfer

First ... disconnecting the battery to clear codes doesn't fix anything.

Second .... get the codes then start your troubleshooting.

iceracer1

Hi, The 4.3 Vortec injector is under/in tne upper intake plenum and consists of one large injector with 6 plastic lines terminating in a spring and poppet pressure actuated(60 psi +/- a couple psi)injector for each cylinder,batch fire.Later years have one injector per cylinder,sequential.The fuel pressure regulator is also in the intake plenum and therefore directly affected by manifold pressure.
On the back of then manifold is the brake booster vacuum supply hose and a small source for accessory vacuum,check these for leakage.Long term rich condition can cause the catalytic converter to melt down causing a restriction in the exhaust.This will cause low engine vacuum which will cause the map sensor to add more fuel etc.Exhaust back pressure can be checked by removing the oxygen sensor and taking your pessure reading there,it should be less than 2 to 3 psi max at 2500 +rpm.
Another problem is the pop can shaped EGR valve,right below the throttle body,will pick up carbon chunks and hold open the EGR valve causing an internal vacuum leak.A special gasket with a stainless steel screen is available through the HELP line of odd bits available at most auto parts stores.
Check your codes and see where they lead you.Test before you condemn a part or you end up replacing a lot of parts. Good Luck