My 94 gmc jimmy exhaust leaves a black mark on the ground?

[shawn b]

It also run great when it is cold but gut-less at times when it warms up and your trying to eccelerate. Engine is the muiltiport V-6 if that helps any. Thank you

 

[wrenchhead6974]

if it is a vortec v6 it most likely has a bad fuel pressure regulator seeing alittle black smoke when you pop the throttle are ya it runs OK cold because the fuel enrichment isn't enough to cause a problem cold a cold engine needs more fuel anyway after its warm it will black smoke and run poorly.

 

[wrenchhead6974]

if it is a vortec v6 it most likely has a bad fuel pressure regulator seeing alittle black smoke when you pop the throttle are ya it runs OK cold because the fuel enrichment isn't enough to cause a problem cold a cold engine needs more fuel anyway after its warm it will black smoke and run poorly.