2004 Yukon power loss then normal

[9C1C]

I have a 2004 Yukon 4WD with 210k miles and it's been bulletproof reliable for the past 2 years I've owned it. Running perfectly fine as usual on a 1.5 hour trip tonight, I then made a stop for about 20 mins. Got back in and fired it up, got 100 feet down the road and it started bogging and dropping RPMs kind of like I was running out of gas (though I had 3/4 of a tank). No CEL came on. I got on the highway and was light on the gas to get up to speed. It ran just fine for the 1.5 hour trip home - even idling perfectly at a few stoplights - with no more intermittent power loss. As I got close to home I took off from a couple traffic lights and it accelerates easily with no bog or power loss. I suspect maybe some bad gas, maybe a fuel pump maybe on the way out, or something worse like the tranny. But I'm no mechanic and would appreciate any help on how to diagnose what in the heck happened.

 

[rockola1971]

This one is going to be fun since its hard to fix something that aint broken. Atleast right now its not broken. See if you have any pending codes!

 

[nonickatall]

That can be a lot of Problems. When did you change the fuel Filter, Distributor, Spark Plugs? Did you look for error codes?

A famos German Rallydriver said once:

You can't treat a car like humans. Cars need love..

 

[9C1C]

I've got a new fuel filter and will be installing it this weekend. I haven't done it on this rig before so I figure it's maintenance I need anyway. Plugs and wires are in good shape. A friend has a scanner and I'll borrow that this weekend to see if anything is pending. It's been running perfect, still.

 

[Tonyrodz]

I've got a new fuel filter and will be installing it this weekend. I haven't done it on this rig before so I figure it's maintenance I need anyway. Plugs and wires are in good shape. A friend has a scanner and I'll borrow that this weekend to see if anything is pending. It's been running perfect, still.

Isn't the fuel filter part of the fuel pump? Or is it mounted to the frame?

 

[Fless]

If it's Flex Fuel (2004) there should be a filter on the left frame rail, near the ethanol sensor.

 

[rockola1971]

That can be a lot of Problems. When did you change the fuel Filter, Distributor, Spark Plugs? Did you look for error codes?

A famos German Rallydriver said once:

You can't treat a car like humans. Cars need love..

Distributor? On a LS based distributorless ignition engine? Watchu Talkin about Willis?

 

[nonickatall]

Distributor? On a LS based distributorless ignition engine? Watchu Talkin about Willis?

To be honest... I dont know...

 

[9C1C]

lol - yeah, no distributor on this and there is a fuel filter on the frame rail since I do have the 5.3 flex fuel.

 

[Tankueray]

I know this is a few months old, but I'm going to call the fuel pump relay. I had (have?) a problem like this for years, eventually it would die while driving, but start back up about 15 minutes later. Threw every part at it and was about to replace the fuel pump when an old man told me to get a relay when I died on the side of the road one day. Most of the parts stores have crappy relays, get a Delco or I've had good luck with O'Reilly's. This has happened a few times in 5 years. I went to the junk yard and got about a dozen of them and keep them in the truck now. Bad relays don't necessarily test bad, and I've swapped out a dying relay for the a/c one in a pinch and the a/c will still work fine, but I know the relay is bad and it's time to get a new one.