Rough idling and bogs down on startup?

[jvoisel]

It's a 02 Yukon xl, 5.3. Filled up and got on the highway and it was fine until I went to pass someone and it started bogging down. When idling it would idle rough and if you gave it gas it would bog but you could slowly bring the rpms up. After a min of revving it it would do fine and drove great for over 100 miles(highway nonstop) got home and when i started it it did it again. Got it to idle fine after messing with it and drove it around the yard fine for a min. Turned it off and now it's doing it again.

Seems to me like the fuel line is losing pressure when you turn it off? Vacuum leak maybe? Oh and the fuel pump/filter was all replaced like 6 months ago.

Oh and we couldn't get it to idle normally until we pulled the air filter off..

 

[Rivieraracing]

Fuel filter! Replace it, it's cheap and easy and see if that solves your problem!!

 

[BlizzardX23]

yep...fuel filter!

same thing happened to me!

 

[jvoisel]

Gonna try that tomorrow and see how it goes. Thanks everyone

 

[BlizzardX23]

good luck!

 

[jvoisel]

Got another question for you, if it's the filter how come it's only when you start it up? It did fine for over two hours after we got it out on the highway running 75-80 then did fine at stop lights in town and all?

 

[Rivieraracing]

If there is garbage in there, sometimes it will settle into a spot that still allows fuel to pass but when you shut off your truck the flow stops, then when you start it back up, the fuel rushs back through and disrupts everything, sometimes plugging up the passage and sometimes not! (Hard to explain)

Keep us informed, hope it solves your problem!!

 

[BlizzardX23]

Also..think about it like this...once your on the freeway at high speeds...your truck is demanding a lot less fuel...

but when your at a red light and it turns green..your trying to force a lot more fuel into the system...

picture this...your fuel filter is 60% clogged..which means its only allowing 40% of the fuel to pass...

In the city, lets say you require 70% of the fuel to pass in order to leave from a red light or stop sign... If its only allowing 40% to pass...then your still missing 30% of your fuel causing it to bog down...

but, if your on the highway, lets say it only needs 14% to stay at a highway speeds (because your staying at low RPMS)...which means your not demanding more then the passage can provide


Im obviously NOT that great at explaining this...lol...sorry

 

[jvoisel]

It's the fuel pump, there's 28psi in the lines and it's supposed to be 60-65psi. Getting a new one installed tomorrow mourning and that's setting me back $695 so hopefully that's all it is.

 

[Rivieraracing]

Hope that solves it, I would still replace the fuel filter while you are at it!!

 

[jvoisel]

I'm pretty sure he said he was going to do that too. I'll make sure to tell him to when I drop it off tomorrow.