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Username Post: 05 Envoy 4200 stalling        (Topic#357316)
gchemist 
Senior Chevytalk Moderator
Posts: 24929
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
07-21-19 03:02 PM - Post#2771243    

A 05 Envoy 4200 is stalling. I go look at it and ask a few questions. A shop could not find any trouble. No codes. The common fuse box problems should be gone. The entire fuse box was replaced. New battery. It starts every time after it cools off. So I'm guessing fuel pump or pressure regulator. It primes to 60-62 PSI and runs at it too. It bounces 2-3 PSI. After a few minutes, I see the pressure swing almost 10 PSI. I show the owner. It's not supposed to do that much movement. After a bit, it goes back to normal pressure. The pump was replaced about a year ago. My guess, it's a cheap pump. A good replacement pump is going to be $150. No need to replace a failing regulator when it's attached to the fuel pump. +04 and older 4200s had pressure regulators on the fuel rail. Then in '07, the system changes again to some kind of pulse pump. There is no return line from at least '05 on.
Before or after this fix, an ECM flash or replacement is likely. A search suggests the ECM could be bad too. Until a part fails or a code pops up, the pressure and ECM issues are my guesses.
Any other guesses?

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 




Shepherd 
Frequent Contributor
Posts: 1848

Loc: Lake George, NY
Reg: 11-11-15
07-22-19 04:22 AM - Post#2771262    
    In response to gchemist

Crank, no start? Lot of bad ignition switches in those trucks.



 
gchemist 
Senior Chevytalk Moderator
Posts: 24929
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
07-22-19 06:16 AM - Post#2771272    
    In response to Shepherd

Shepard,
I forgot to mention the ignition switch was replaced too. One more reason I'm suspecting the ECM besides the bouncing fuel pressure.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 
Shepherd 
Frequent Contributor
Posts: 1848

Loc: Lake George, NY
Reg: 11-11-15
07-22-19 07:29 AM - Post#2771276    
    In response to gchemist

I owned one for 155k miles, did a lot of work on it in my shop. Pcm failures are very rare. What are your symptoms? Will it start praying carb cleaner into the intake, got spark at the plugs



 
gchemist 
Senior Chevytalk Moderator
Posts: 24929
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
07-22-19 07:49 AM - Post#2771281    
    In response to Shepherd

While driving it randomly shuts down. It will start up every time after cooling down. The owner previously wiggled the fuse box. It would start up. So the owner had the dealer replace the box. I'm not sure who replaced the ignition key switch. I had a car that stumped me for a long time trying to find a starting problem. It was finally traced to a crank sensor. Do these have a problem with crank sensors?

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 
Shepherd 
Frequent Contributor
Posts: 1848

Loc: Lake George, NY
Reg: 11-11-15
07-22-19 01:45 PM - Post#2771319    
    In response to gchemist

Anything can happen, heat based, but generally the cps is not a problem. You need to isolate fuel vs spark to figure this out. I assume no pending or history codes?



 
gchemist 
Senior Chevytalk Moderator
Posts: 24929
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
07-22-19 02:53 PM - Post#2771327    
    In response to Shepherd

No codes. I'm going to borrow a good fuel pressure tester and run it for a longer period of time. Tune up is recent too. I don't have a lot of time to spend on it. I'll check on it as I have time. In the mean time, I'm making a list to run through when I can.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 




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