ok so i just put my truck in shop not dealer. guy said my valves were sloppyest he has ever seen and my timming was at 12* he reset to 16.5* and adjusted valves going to road test but says it will be a new animal. my question is 12*-16.5* is that huge or not?

 

huge? well thats a big jump yes. will it make a difference. yes. 12 is below stock. and 15.5-16.5 is a really good spot for the mildly hotrodded engine, or even a stocker.

 

With 16.5 you'll have more power and get better mpg.
Downside is you'll make more smog...

 

just picked up truck and all i can say is wow...what a differance..tank had less than 1/8 so i filled it up wrote millage down i will let you guys know when its empty what i got.

 

ok filled it up today 31.6 gallons to the rim, 309 miles,= 9.8 mpg not great. anyone have any ideas on what eles to try?

i pull a 5k lb trailer all day and drive in the city no highway.
am i expecting to much outa this truck?
i hear about 15-18 mpg same truck are they full of @#$%.
i try to keep it under 2k rpm.
will the sending unit in the tank affect it? mine is bad.

 

I think you should do the fuel mileage test again, maybe a couple more times...try it with out the trailer if possible.
Try it with overdrive off as to not "lug" the engine...10 mpg towing in town w/ stop and go is not terrible, but not that good.

Also the guys w/ the same truck getting 18+ are not "full @#$%"
I consistantly get 18+ mpg out of my 12 valve... I have a manual, but Ive got bigger injectors, and a tweaked pump. also running 285s on 17" steelies(HEAVY!)

Last time I towed the boat anywhere far was to Calif. and back...(never again) The boat/trailer weigh about 5-6K. got 12-14mpg towing at 70 or so.

Are you running big tires? or do you have 4.10 gears?

Scott

 

runnin 285/75r16 stock rims
automatic i will try overdrive off just dont see what diff. it makes
stock injecters although i have 150hp over stock (not installed)
straight pipe,
and 3.55. would bigger rear end help cuz i work out of this trailer so i need it every day.
allso i have new cold air box shgowin up tues.

 

Hard to say about the gears...3.55 tend to be better for highway mileage and 4.10 tend to tow better, especially up and down the mountains.

...Let me think about some things that affect mpg's
1. Right foot/ Driving style
2. Clean fuel/fuel filter
3. Tire Pressure
4. Weight of truck
5. Weight being towed
6. Pump timing
7. Axle Gearing
8. City vs. Highway
...probably more but you get the idea. Start with the easiest or most obvious like driving habits, and a new fuel filter.
If you'd like to get together and compare apples to apples Im close so just say when.

Scott

 

i bought this truck new..got 450ish miles out of a tank 36gal =12.5 mpg..
truck went to dealer for a stallin issue..rmp droped to 450-500..@ 30k miles..

they said they did valves..truck didnt stall anymore..now im gittin 300 miles
to a tank..=>10mpg..

just got truck back from a custom diesel shop, timming was at 12* (set by dealer)now its 16.5* first tank no diff.
new fuel filter every 5-7k miles..and i do my best to keep my foot out of it.

what eles would the dealer have done to it?

 

Start at the beginning, verify your fuel pressure.

 

Are you actually putting in 36 gallons to fill it? Most I have ever put in mine was 110 l, which is about 29 gallons.

 

Same here Tate. I have never been able to put that much in except when I had pulled the tank and drained it....

I really saw a marked inprovement in mpg when I replaced the lift pump, filter, cleaned the screen and replaced the overflow valve. (all related to fuel pressure) Smartest thing I did was to put in a fuel pressure gauge to alert me to the problem....

 

My tank takes 32 gallons from dead empty. I found out the hard way and had to replace the fuel filter due to all the crud I sucked up. With stock timing I see 10-13 mpg in the city, but around 20 on the highway, regardless of load. I intend to bump the timing to 15 degrees as soon as I get a break from buying other parts, I need to purchase the puller and dial indicator.

 

I think you are calculating your fuel mileage wrong...divide your miles driven by the gallons you put in the tank...NOT miles driven divided by 35 gallons.

 

which is what i did.. 31.6 gallon 309 miles=? 9.8...post #5 and i have actually got 34 gallons once..

i do not have fuel presure gauge but will soon also just put in my new s&b air box and getting ready for fass lift pump with new fuel moduel, sending unit..