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Discussion Starter · #1 ·
Hi all....

thought i'd ask the experts for a hint or 2 if ya wouldn't mind.


'03 Envoy SLE, 89,700 miles....this things been a pain, unfortunately.

i had a huge crack in the exhaust manifold.....changed it out, and trouble began. basically, i have no power, and i mean none. it will start and idle fine, but stompin the gas only gets 2500 rpms in neutral. it wont drive anywhere (well besides in the driveway).

changed the fuel filter, but no improvement. at that time, i noticed there was essentially no fuel pressure in the rail (depressing the pressure relief valve yields no gas).

im thinkin a couple things....pump or the regulator. then i stumbled upon the TB about the pumps corroding.....could this be a problem?


i appreciate any input or insight from the great folks here. i would rather fix this myself, but i just wanted to get another perspective before i start shotgunning parts.

thanks all, and take care!
 

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2002 chevy trailblazer_lt_ext
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There is a recall on the corroding fuel tank issue. Good for 150,000 miles, I believe. If you have this issue, you would constantly smell gas fumes in and out of the vehicle. This should also set an EVAP/Emissions code. Is your check engine light on? If so, what is the code?

Also, have you checked the fuel pressure with a gauge at the service port? The port is located at the fuel filter.

Could also be a clogged cat?

Hope this helps.
 

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2003 chevy trailblazer_ls
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I think that in park.. (and I think Neutral) the computer limits RPMs to about 3500....

but you say 2500... hmmmmm...

clogged cat?
 

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2007 chevy trailblazer_ls
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I think that in park.. (and I think Neutral) the computer limits RPMs to about 3500....

but you say 2500... hmmmmm...

clogged cat?
:iagree: Could definately be a clogged cat especially with the cracked exhaust manifold. How much driving was done with the cracked manifold?
 

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2003 gmc envoy_slt
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:tiphat Welcome :tiphat .When you changed the exhaust manifold, did you remove the air intake resonator? Did you remember to reconnect the fuel regulator vacuum hose?:m2:
 

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Discussion Starter · #6 ·
sorry about bein away....busy busy busy....

neeskit: i dont smell any gas....and no codes or dummy lights. so i dont think corrosion problem is here (yet...). i haven't measured the line pressure yet, but will have access to a gauge soon. is there a difference between the service port by the filter and the service port by the brake booster?

rbarrios: and it takes about 5 seconds to get too 2500rpm......

07BlazerMan: alot....maybe 2k miles.....it started to crack in the winter, and my other car is a bike...:duh:

wooluf1952: air intake resonator? i hope so.... vacuum hose, dont think i removed one. in swapping the manifold, i disconnected the mass flow sensor? (in the intake duct), and the O2 sensor. i was able to remove the manifold and heat shield without removing anything else......

sorry i dont know the proper names for the assemblies.....i'd probably know it to see it.....


i do appreciate all the replies....never considered the Cat....:thx
 

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Discussion Starter · #8 ·
i finally got some viable info....

- checked the fuel pressure at about 59psi at idle on the bottom tap by the fuel filter.....the return line i believe.
- pulled the plastic intake reservoir (?) off the top of the engine to check the vacuum as well. measured at the tap on the throttle body just behind the flapper (?lol) at about 15 in of water, and it was steady. doesn't look like there are any misses, but we couldn't quite check the CAT. i still need to check the plastic housing for cracks, as it didn't seem to be pulling any vacuum to the fuel pressure regulator.
- plugged in a scan tool, CAN OBD2.....got no live data, no DTS drivetrain(?) data, and no codes. nothing.....(my co-worker who owns the scan tool) basically said it was like the PCM link is OK, but there is no data to read.


gonna see how much the dealership will ask to look at it....these are a far cry from the muscle cars im a bit more used to. if anyone has any advice i'd be grateful. i'll be sure to finsh out this thread though if/when it gets resolved.

thanks for lookin!
 

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2009 chevy
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So, break it down systematical.

Sounds like it worked fine until the manifold was changed.

Therefore, must be something to do with changing the manifold.

Look at all electrical connection that are near the work area.

But, the big money goes on something dropped into the exhaust pipe, blocking the flow.
 
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