Blubber/loading up on initial start up.

**sjodin** · 02-12-2008, 08:08 PM

Hey guys,
I just bought a used 2000 Silverado extd cab with a 5.3L/auto, 87k mi. on it about 2 mos ago.
I've noticed here lately on start up, the engine has a little trouble starting up clean. Not everytime, but alot.
Didn't used to do AT ALL. It doesn''t seem to matter whether it's a cold intial start up or after it's been shut down at operating temp. It's occuring at random-and quit frequnetly at this point.
It appears as though the engine is "loading" up or too much fuel has been dumped in the combustion chambers-as sometimes I catch a slight bit of dark smoke in the rear view mirror. No codes.

Any ideas on what the deal is here? Thanks! I apprecaite the feedback.-R

**GMTRUCKLOVER** · 02-12-2008, 09:19 PM

Sounds like the fuel pressure regulator is bad. I've replaced mine on 2 different trucks I had. A good way to check for sure is to test it. What I mean by that is, when the engine is at normal temp, pull the vacume hose off. If raw fuel sprays out, it's bad!
The fuel pressure regulator is located on the driver side of the plenum and has a vacume hose hooked to it. I changed mine in the Napa parking lot, it's that easy!

**dwill3015** · 02-12-2008, 09:43 PM

I researched recalls for your truck and found that your model has a defective fuel pump so the fuel delivery system is worth checking out along with a new fuel filter. The dealer just replaced the fuel pump for free on my Wife's 2001 Suburban 5.3 (same recall).

**sjodin** · 02-12-2008, 10:24 PM

Yeah, I've been meaning to get that thing over to the freindly Chevy dealer, to run the VIN for SBs & recalls.
The truck runs absolutely fine outside of this issue.
I also want to get my transmission flushed. Figure it definately needs that.

Thanks again. -R

**LANDBARG** · 02-13-2008, 12:33 PM

MAP sensor will make the truck run wacky too (too much fuel or not enough) and it won't throw a code until it totally wipes out. Mine was bad and it never lit the SES. had the same problem in a pontiac I had once too. MAP sensor went bad and it dumped so much fuel in the cylinder it wouldn't burn it all and I got black all over the rear bumper AND gas in the crankcase.