Losing 50 miles per tank on mileage - help!

[sparg93]

other than oil pump, any other changes you have made to you rig?

If none of the changes the gents above mentioned work, one item might be the fuel pump itself...just my thought when u said that when you pressed ******* the accelerator, not too much happened.

 

[DjLarroc]

Air filter?

It's not new, but I checked it and it's clean.

Where do you live and are they adding ethanol or any other winter additives to the fuel? Do you have winter tires on now, which because of their design tend to be less efficient? Is it cold and do you autostart or otherwise warm up the truck? That one kills my winter mileage...warming up the car. Tire pressure ok?

Just a couple of other ideas....

I'm in CO. No new additives as far as I know. Usually fill up at the same place. I have the same tires as before. They are an aggressive all season. No auto start. Tire pressure is good.

Sounds like your cats are crapping out or plugged up, when mine in my Blazer finally plugged up, the more I stepped on the gas the slower it actually went. Try tapping on them and see if you hear anything loose or rattling around in there. Does you exhaust sound any different, kinda like it is breathing through a scuba snorkel? Decrease in exhaust flow out of the tailpipe? Truck running any warmer than normal?

It's running pretty normal. I'll check the cats. You may be right. How much were they? Just curious.

Are you letting your truck idle longer during the colder mornings, no offense but winters are notorious to drag down gas milage from crap you may over look. Also your truck has to run harder due to the viscocity of the oil when its cold

No long idles. Everything is the same which is why I'm stumped. I've had to use the 4WD, but it's been so minimal, I'm very doubtful that's the culprit.

other than oil pump, any other changes you have made to you rig?

If none of the changes the gents above mentioned work, one item might be the fuel pump itself...just my thought when u said that when you pressed ******* the accelerator, not too much happened.

No other changes. Anyway I can tell it's the fuel pump? The truck starts right away every time. Although I know bad fuel pumps are common in these trucks right?

So does everyone think I should start w/the injectors? When I step on the accelerator (and this happens about everytime I drive the truck - usually at the beginning) the truck stalls bad. It moves along better accelerating very slightly until I can tell, it's normal.

 

[Eagle]

Winter fuel could be some of it.

sounds about right for winter gas...

 

[DjLarroc]

Ok. So maybe what I'll do first is run a bottle of heat through it to kill any moisture in there. Last winter this did not happen, and I would have noticed this for sure. Plus I track my mileage and maintenance on mycarprojects.net so I have it all logged since I bought it last November.

 

[possumsquisher]

Make sure to check the oxygen sensors. If they are not cycling properly it will kill your gas milage. Mine dropped from 17 to 13 with no check engine light. Found out both rear sensors were slow.

 

[Eagle]

that is PROBABLY what is killing mine... averaging about 11.8-12.4 no matter how aggressive or nice I drive.

 

[Redraider yukon]

New member

Just wanted to introduce myself. Joined last week and glad i found you guys. I've always been a truck guy(F-150), but after transmission problems for a second time in 3-4 yrs I bought a family members 01 Yukon 4x4 SLT 3 months ago. Looking forward to catching up on some of the posts on here and plan on putting wheels on my yukon next year. From some of the pics I've seen I might just check out pics and not post one of mine until i get it up to par. You guys have some nice looking wheels.

 

[DjLarroc]

Update

Hey guys, I'm a firm believer of updating, even if the problem/fix was minimal.

I checked the air filter, and hoses, and all seemed good.

I ran a 1/2 bottle of heat (yellow bottle) in my last 3/4 tank. Within the first 100 miles, the hesitation went away, and my last tank reached 305 miles before the low fuel lamp turned on. Almost back to normal. I only ran a half bottle.

I just poured a full bottle into a full tank, but it looks like things should be back to normal. Musta just been bad winter gas as mentioned, or had water in the tank/lines.

 

[ActSwedish]

Congrats that it´s running better. What is heat? is it like something that takes away the water or some other additive?

 

[vatahoelt]

i still say it's cause of winter fuel.