Okay so for those who don't know, I have a 2003 GMC Sierra with the 4.8liter and auto tranny. It has about 45,000 miles on it.

Anyway it's having the same problem it had before. After I driven it for say 30 minutes and park it somewhere for a few hours, when I go to start it it will try to start then stumble and stall with the starter quickly spinning over(too quickly). Usually you try it again and it fires up, bogs for about 2 seconds, then it's fine from there. Tonight however it stumbled and stalled on me twice before I could get it to start up and the check engine light came on. I had the check engine light scanned with an el' cheapo scanner and it said Small Evap System Leak Detected. I think it's possible this could have just been an intermittant glitch due to the whole starting andstalling issueand probably isn't the problem. I might also add it only seems to do this when it's at about 1/4 tank or less of fuel. If it's at say 1/2 tank of fuel it won't do this... atleast I haven't noticed it do this.

I know this is a lot of variables but I didn't want to withold any information that might help me diagnose this. Whatever it is, it seems to be some kind of a fuel pressure related issue. I've recently replaced the fuel pressure regulator and that didn't fix it although it seemed to make it a little spunkier for a few days.

 

****. you need to just talk to a mechanic

 

Yeah, well there are a few mechanics on here so that is the idea.

 

have your gas cap on?

 

Im having very similar problems with my 02 Silver 4.8L I just check fuel pressure and its 21lbs so mine is fuel related and I also replaced the Press reg too/ this has been running like this for over a year still cant find problem but pressure leads me to the pump so thats my next step

 

i imagine the pump is acting up....do you have access to a pressure gauge??

 

No but I've thought about buying one. Can you just hook the guage up to the schrader valve on the fuel rail or does it need to be hooked up somewhere else?

If it ends up being my fuel pump I am so gonna send GM a long letter of complaint. I have just replaced both my Dad's 2000 Sierra's fuel pump and my sister's 03 Cavalier fuel pump. My truck only has about 45,000 miles on it. Maybe with enough complaining I can get them to warranty it out.

 

Yes you need a TBI Pressure guage It hooks up to the Schreder valve on the fuel rail should be on passenger side of the engine.I just got one on ebay for 29 dollars and it worked good
I can try and find it hold on This is the one I got TBI Fuel Pressure Tester Kit by Actron CP7817
http://cgi.ebay.com/ebaymotors/Actro...spagenameZWDVW

 

Thanks for going through the trouble of locating that for me. Fortunately I work for O'reilly's so I can get them for about the same price or less at work.

How much fuel pressure should I expect to get out of it? Also, is it possible this could be an intermittant problem with the fuel pump considering it works great 99% of the time?

 

after you hook up tester Turn key on engine off and you should show 55-60lbs if pump is good
then after you shut it off pump should still be holding pressure until you bleed it down again.
I believe it might be a little higher not much with engine running
see what yours is To bad you just cant borrow a tester or have a friend do it for you and save some bucks
These pump arent cheap Good Luck