Getting 8.5 mpg need help

[BlueCollarTahoe]

pics above are of the tank dropped and what was seen. the whole thing smelled like gasoline. the metal nut thing on the top was rusted almost shut. they sat it in ********* for 30 min or so. got the old fuel pump out....the float inside had no resistance. just kind of spun around lol all thoe connecting lines that come out the top were rusted almost complete through. the top of the pump had a hole right behind that black connection it was just covered with rust. put your thumb on it went right through. new pump installed running normally. smell is slightly still there i think on the chassis where it was spilling. i filled the tank..204 miles is the est. the miles were going down much slower today though after the replacement. should i still check for a gasket leak graph new info with new pump po455 code is gone btw.

 

[Scottydoggs]

if the code went away on its own, you fixed that issue up.

never seen a pump canister top rot out like that before. most of em are all plastic.

give your trims a few days to learn, check em then. hope you gain some mpg back now.

 

[BlueCollarTahoe]

if the code went away on its own, you fixed that issue up.

never seen a pump canister top rot out like that before. most of em are all plastic.

give your trims a few days to learn, check em then. hope you gain some mpg back now.

one of the mechanics said the same thing. think some salt mightve gone up there over time rot it out? the acdelco one i put in the top of it is metal. like a stainless steel it looked like.

cool hopefully it works out i can get some more spread on a tank full.

 

[HiHoeSilver]

if the code went away on its own, you fixed that issue up.

never seen a pump canister top rot out like that before. most of em are all plastic.

give your trims a few days to learn, check em then. hope you gain some mpg back now.

There is a little "pool" up there where the water sits.

one of the mechanics said the same thing. think some salt mightve gone up there over time rot it out? the acdelco one i put in the top of it is metal. like a stainless steel it looked like.

cool hopefully it works out i can get some more spread on a tank full.

Spayed mine with bedliner when I changed it.

Old.

New.

 

[BlueCollarTahoe]

update:

the gas seems to be lasting alot longer so far. the avg mpg goes up between 9 and 11 depending how long im on the highway. the miles seem to go down alot slower now on the estimation. but...PO455 has returned and i still smell a slight vapor smell from driver side. no where near as bad as before but i noticed it, ugh. may have to go back and see if something from the gas cap area down is loose or something. can i run a smoke test through the gas cap to try and find the leak? like backwards instead of from the front at the engine bay evap hose?

 

[Scottydoggs]

you sure can put the smoke down the gas tank filler neck.

if you smell gas then you'll likely find more smoke coming out of somewhere once more.

 

[BlueCollarTahoe]

hose to tank from the filler neck was loose...replugged cleared code and hasnt returned

 

[swathdiver]

How's the mileage now? Mine's finally doing good, especially on E85.

 

[BlueCollarTahoe]

How's the mileage now? Mine's finally doing good, especially on E85.

its definitely improved but not as much as id like. looking like im gonna get 230-240 out of a full tank after the replacement.

 

[swathdiver]

Let things wear in and adjust and see how it does after another 2-3 tanks of fuel.

 

[BlueCollarTahoe]

gonna give it a month straight and see where its at in july. i got the "tighten gas cap" message today i checked and the hoses aeew all connected still. well see what happens.

 

[BlueCollarTahoe]

LONG UPDATE:

been a while since i updated this and ive come to the conclusion that 8.5 is normal. I spent a week or so in another state..very rural part of PA...highwaY driving and country roads with no lights....when i went to refill the tank out there i was getting an estimated 340 miles per gallon. the gas lasted so much longer. the drive back to nyc resulted in a fill up...highest i ever saw...371 miles for the tank estimated. once i got back to the stop and go city driving...back down to 220...200..210. its the stop and go that really kills this truck. i got the emissions code out there...slight smell of gas with the AC on and wehen i throttle the pedal so there is defintiely leak somewhere in the lines...will fix soon.

 

[swathdiver]

LONG UPDATE:

been a while since i updated this and ive come to the conclusion that 8.5 is normal. I spent a week or so in another state..very rural part of PA...highwaY driving and country roads with no lights....when i went to refill the tank out there i was getting an estimated 340 miles per gallon. the gas lasted so much longer. the drive back to nyc resulted in a fill up...highest i ever saw...371 miles for the tank estimated. once i got back to the stop and go city driving...back down to 220...200..210. its the stop and go that really kills this truck. i got the emissions code out there...slight smell of gas with the AC on and wehen i throttle the pedal so there is defintiely leak somewhere in the lines...will fix soon.

Very similar with mine too Jay. Most of errands are within a few miles of home and there are so many lights and stop signs there's usually not more than a quarter mile between them. It just tanks the mileage. It now averages 20 mpg @ 65 mph but drops to 18 @ 70 mph and 17 @ 75. Keep us posted about that smell/leak, that's going to cost some too.

 

[bottomline2000]

LONG UPDATE:

been a while since i updated this and ive come to the conclusion that 8.5 is normal. I spent a week or so in another state..very rural part of PA...highwaY driving and country roads with no lights....when i went to refill the tank out there i was getting an estimated 340 miles per gallon. the gas lasted so much longer. the drive back to nyc resulted in a fill up...highest i ever saw...371 miles for the tank estimated. once i got back to the stop and go city driving...back down to 220...200..210. its the stop and go that really kills this truck. i got the emissions code out there...slight smell of gas with the AC on and wehen i throttle the pedal so there is defintiely leak somewhere in the lines...will fix soon.

I didn't read through the whole thread but have you pulled the vacuum line off the fuel pressure regulator? If you see fuel then the regulator is bad. Also have you put a pressure gauge on the fuel line to see if it's dropping pressure at the rail? Could be a stuck injector.

Sent from my SAMSUNG-SM-T377A using Tapatalk

 

[BlueCollarTahoe]

I didn't read through the whole thread but have you pulled the vacuum line off the fuel pressure regulator? If you see fuel then the regulator is bad. Also have you put a pressure gauge on the fuel line to see if it's dropping pressure at the rail? Could be a stuck injector.

Sent from my SAMSUNG-SM-T377A using Tapatalk

yes its been checked multiple times...normal. there is no regulator on the fuel rail i checked and was gonna replace it but it isnt there.

 

[sonic_the_hedgeh]

I had some fuel economy problems as well. Did and intake clean of my throttle body. Also I found under the plastic cover on top of the engine, a built in pcv valve and line. I cleaned through the hole into the engine and that helped a lot.

Sent from my CLT-L04 using Tapatalk

 

[sonic_the_hedgeh]

Also I did try some Lucas lubricants Fuel additive. Works really well. Around town my Yukon is a lot better on fuel than before.

Sent from my CLT-L04 using Tapatalk

 

[swathdiver]

Also I did try some Lucas lubricants Fuel additive. Works really well. Around town my Yukon is a lot better on fuel than before.

Sent from my CLT-L04 using Tapatalk

From what to what?

 

[sonic_the_hedgeh]

From what to what?

I haven't actually measured it but I did try an experiment for the past 6 months. Instead I add 2 to 4 liters of 5w30 to the tank of fuel and again much Better fuel economy. On one trip going just over 300 km's I used quarter tank of fuel.

Sent from my CLT-L04 using Tapatalk

 

[sonic_the_hedgeh]

Update. So far I will complete my year of testing using oil instead of Lucas lubricants. Cheaper does the same thing. In colder weather use 5w30. I have used up to 10w40 and used 2 to 3 liters per tank and works great. Exhaust is still clear and fuel is lasting much longer.

Haven't tested yet in winter weather but this winter it should work fine even with minus 30 celcius. I will use 0w20 for that cold.

Sent from my CLT-L04 using Tapatalk