05' H2 SUT.

Modifications to consider:
(At 50K miles) Lacked towing power therefore, installed supercharger kit including a larger in tank fuel pump; (At 53K miles) Speedo incorrect therefore, hadentireinstrument cluster rebuilt with new stepper motors etc.;(At 56K miles) Tranny blew therefore, had tranny/torqueconverter rebuilt/transfercase servicedand (At 56K miles) replaced sparkplugs andsparkplug wires.(Note: I always change oil, oilfilter, airfilter at regular intervals).

Problem:
Gas mileage is erratic andgas guage seems inaccurate. Weeks after I installed the supercharger kit I noticed the fuel mileage went down. I thought it was due to the supercharger and related larger fuel pump or a slipping transmission. While towing 6400lb trailer, I noticed mileage went way down. Yet,with no load it seemed it was wasusing an abnornal amount of fuel. THEN, a week ago, I was very near "E" on the gas guage but light had not come onjust yet. I filled the tank and it took only 21 gallons, yet it has a 32 gallon tank. TheH2 computer system says I am getting 11.8 mpg. Sometimes under the same driving conditions, it appears that I use far more fuel than normal.

Currently, I am monitoring fuel usage. So far the first quarter of a tank showed 86 miles of use, the second quarter of a tank shows about63miles of use. I am on track for300miles of use from a tank of gas (before low fuel light comes on). I have no ideal how much gas reserveafter low fuel light comes on.

What is the problem?
Is it thenew gas guage stepper motor in the instrument cluster OR fuel sensor on top of the fuel pump OR fuel pump float in tank OR something eles?Thanks for any input.

 

The supercharger might have screwed the computer up and now the hummer is confused.....I have no idea and you should seriously consider a dodge ram deiselor something with more power

 

ive had the same problems... mine reads 11.3 mpgwhich would give a range of 360 miles or so But i have gotten almost 550 from a single tank. I have also had the speedo problems along with voltage and oil press. guage issues.these arent the issues i want when i spend 60k on a truck.. I want an 08 but i dont want any issues at all!!! i dont have time to deal with dumb problems.

 

HMH2SUT you say you have gotten almost 550 miles per tank? So you are averaging around 18mpg?


Tim

 

It really seems to good to be true but heres what happened. I drove from Exit 16 NYS thruway to plattsburgh Ny to visit and Friend. its ruffly 260 miles. I filled up just before we left. When I got there I got the usuall comments "How much that cost to fill up?" from my buddys. so i checked to see what was left and the guage read 1/2. I figured the guage was on its last leg or had already broke. i drove another 30 miles while in town, so 290 so far. the guage was still stuck at 1/2 i couldnt stop looking at it iwas pissed that i was having another guage problem to add to the list. My girl friend said i was like Cramer in seinfield when he drove the car to bone dry! before we left I boughttwo 5 gallon containers and filled them up.i left with 10 gallons in the bed. about 30 milesnorth of albany the low fuel light and then range Read LOW. I figured any minute I would start spuddering out but it kept going. I stopped at the New Baltimore Rest stop south of albany to use the bathroom when I started the truck back up the range read low again but I wasnt stoppin. I made it off the thruway and just past the original gas station before It finally pooped out. I put the 10 gallons and drove home. ruffly 550 miles 260 miles eachway = 520 plus 30 in town 550. I am still puzzled myself because i have tryed this again and only gotten 340 miles less then what my 11.3 mpg should get.