2004 high speed misfire and stall

[coyote54]

Recently purchased a 2004 Envoy XL with 30,000 miles.

Worked great for 6000 miles then all of a sudden at freeway speed, it sputtered once then came back to life and was fine for the next 150 miles.

2 days later again at freeway speed it started to miss then died. Coasted to the shoulder, put it in park, and it restarted and sputtered the next 20 miles where I stopped at NAPA and put in some HEET, topped off the tank and it was good for another couple of days.

Several hundred miles later it again sputters and stammers at highway speed and dies. This time it threw a p0171 code. So I changed the fuel filter. Again it works fine for 100 miles and then all of a sudden it stutters and sometimes dies but always at freeway speed, and will always fire back up, but sometimes it will still sputter badly for a while before it runs "normal".

Could it be the fuel pump already at 30,000? What would cause the intermittency? It only threw the code once. It doesn't always turn the check engine light on.

Thanks,
Tim

[maxwedge]

There is no easy answer for this, I'd road test this and have a fuel pressure tester in place when it happens, that is tough. The code is a lean code which come be triggered by low fuel pressure, misfires or a large vacuum leak. This will take some fooling around from a diagnostic stand point.

[BRD]

Guys, XL of that vintage has a GM recall due to the frequency of fuel filler pipes breaking loose from the gas tanks = vacuum leak. A GMC or Chevy dealer's shop should check it first order of business.

[maxwedge]

This would only occur when the pcm commands a vacuum test on the evap system, and then it is a very small source, I have never seen this set a lean code, good info though.

[coyote54]

Well, you guys beat me to it as the fuel tank was cracked at the filler neck, and I wanted to see if this could be the cause of my problem, but sounds like it might not be.

As a sidenote, my Envoy XL is 400 serial numbers away from the TSB that recognizes the cracked fuel tank. This vehicle has 30000 miles on it, out of warranty by 5 months and GMC customer service wouldn't offer a kickback on the $810 repair. That's fine because I know legally they aren't bound to fix it or even offer a kickback, but what peeves me is when I called customer service to inquire, they said if I was a repeat GMC customer who bought the vehicle new from a GMC dealer (this is my first GMC, bought used, from a Saturn dealer) that they would do the repair for nothing. I think that's crap. I told the Cust. Serv. rep AND his supervisor that I probably won't become a loyal GMC customer after hearing that.

Am I wrong? or just being a crybaby?

[BRD]

Tim, it does NO good to unload on the GM Customer Svc call center personnel. The first or second person you talked with has authority to allow or disallow your request for cost assistance. For example, it's nearly always a waste of time to insist on talking with a manager or trying to call or write Rick Wagoner. OTOH, since you are a customer of a GM Saturn dealer (albeit the dealer's used veh operation) and yours was low miles when you bought it (still low miles), it'd be worth a try to go back to the Saturn dealer and ask their service dept to advocate with GM Customer Svc on your behalf. There is definitely a GM reputational interest at risk in this case in that GM sells basically the same product as your Envoy under the brands of Chevrolet (TB), GMC (Envoy), Buick (Rainier), and Saab (9.7). Add to this the abundance of failures GM is dealing with on the XL/XUV body's fuel filler pipe-tank connection. In short, this is one where I think GM Customer Svc can & should try a little harder if it's presented just right.