Hi,
I have a 2002 4.3 gen2 all stock L35(poppets). It just started giving me a loud noise from the exhaust tail pipe/muffler area during first startup(cold). The noise is right as the engine starts and is short. It sounds like a high performance muffler during a start up. Something like a rummble or gargle.
When I rev the rpm's it comes back as the engine decels just like when it started up but will eventrally stop after a minute or so of rpm reving.
Any suggestions would be greatly appreciated.
I was thinking on checking the static fuel pressure when I get home to see if there is a leak within the plenum.
Thanks

 

Exhaust leak?

 

How did you come to the conclusion that a loud exhaust may be caused by a leak in the fuel system? Just curious!!

Post a sound clip!!

Sounds to me like you may have a bad exahust gasket and when the engine is cold the steel shrinks causing a leak and then when it gets hot the steal expands filling the hole. Might sound dumb but I've seen it alot on alot of different vehicles.

 

No leaks.

Just thinking maybe that there could be excess fuel in the plenum area from a bad regulator and the excess fuel causing backfire in the exhaust during start up, not sure, just an assumption at this piont.

Thanks

 

Problem solved, I just got done figuring it out. It was a warp/dimple/bow or what ever you call it in the outer shell(sheet metal) of the muffler. Kinda like a snapple lid or washing machine lid. It was basically vibration, once the muffler warms up the dimple goes away. When cold I was able to milipulate the dimple not be so concave in that spot. Kinda weird but that is what it was.
Thanks

 

Glad to hear you got not figured out! And thanks for posting the results incase anyone else encounters this on the future

 

Real glad you got it figured out. That is the main reason I questioned for the fuel problem, usually when exhaust is loud. its exhaust related. Glad you got it figured out.