Hey, I’m new here and looking for some ideas. I have a 2008 Tahoe 5.3 with 96k miles and I’m having some starting issues. It seems like it starts acting up when it is heat soaked but even then it doesn’t do it all the time. When I go to start the vehicle it like misfires for a second or so then starts up, some times are worse than others. It also has a slight rough idle. I couldn’t figure it out so I took it to reputable shop and they said the only time they got it to act up was when they had it heat soaked and turned it off it said the fuel pressure was climbing of key off engine off. So, they seemed to think the regulator could be sticking open. So I replaced the whole fuel pump assembly with an acdelco. It seemed like that took care of the issue for a few days, no starting issues and smooth the idle out. Then it started acting up again with the same symptoms. They did a leak down test on the injectors and those tested good so I’m kind of stumped. I checked the fuel pressure and it is in spec even had my buddy who works their double check with his guage just to make sure. The check engine light has never came on and also has not had any codes stored. Is it possible that my fuel tank could be holding slightly more pressure than it should causing an issue? Also I went ahead and changed plugs and wires because it was due anyways but the plugs didn’t look very bad. Any help I would really appreciate, I’m just looking for any direction to go after.
Starting Issues
- Thread starter Breezy13x
- Start date
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clean the maf and throttle body, new air filter, have the maf readings checked, sounds like you haven't done that, takes air+fuel+spark
also, how may miles? have the cat's been changed? if nothing else pans out maybe have a backpressure test done
also, how may miles? have the cat's been changed? if nothing else pans out maybe have a backpressure test done
wjburken
Supporting Member
Your pressure regulator is up on the fuel rail under the hood. If you replaced the pump, that is not the pressure regulator.
I’ll haven’t checked MAF readings or clean that’s or the TB I’ll try that and see if it helps. It has 96k miles on it and I haven’t changed the cats since I have owned it. So I’m doubting that they have been changed. And as much as I wish the FPR was on the fuel rail on the Tahoe it isn’t. That was the first thing I looked for when is started having issue before I took it to the shop as that was what I thought the issue could be and they are normally easy to change out. Then as I found out it was in the tank so, I figured I better have it doubled before I had to drop the gas tank.
What is missing when the problem happens? Like @Doubeleive said, air+fuel+spark. Start with the maf cleaning and throttle bore cleaning and you are worried about tank pressure....loosen cap each start attempt and see if makes a difference. May set a code though for that. Doubt you have backpressure probs because should not effect until start and accel as far as I know. Are you saying it does not crank a long time and never starts till cool down or does start ok and then seems to misfire? Or while cranking it seems to fire then not fire or hiccups during cranking sequence?
By the way, welcome to the forum.
By the way, welcome to the forum.
Plugs and wires still original?
I have 220K on my '07 cats. Doubt that's the issue unless they've been damaged.
I agree unlikley but if nothing else pans out....
Honesty the pressure in the gas tank was just a shot in the dark, it was the only thing that made sense of installing the new fuel pump assembly and only fixing the issue for a few days. I thought maybe it was slowly building pressure over a few days to cause the same issue when I started. And as far as starting when I turn the key over it cranks as normal then acts like it’s going to start stumbles for a second or 2 then starts. Best way I can describe how it acts is when you try starting a vehicle you left of key to early and it like stumbles before it starts if that makes any sense. Haha also to me it almost sounds kind of like a spark knock, but anyways it runs good other than that slight rough idle.
Thank you for the welcome to the page, everyone has seems really help for and friendly.
@Geotrash I just put new plugs and wires on it a few weeks ago. They were both ac delco.
swathdiver
Full Access Member
What are your LTFTs at idle?
How old is the battery? The way you describe the problem, it sounds like the cranking rhythm is interrupted when you have the key cranked over in the start position. Check battery cable connections.
