So, when i got the truck it was only gettin like 12-14mpg. On the way back from Fl I had one tankfull get 21 mpg. Then it disappeared. That was before any mod. Now i'm gettin like 10-11. I know i need to bump the timing, but seriously 10 mpg

 

Does it smoke all the time? What does your temp gauge say? If your thermostat is stuck open you'll dump a lot of heat out the radiator and your temp gauge will be low.

What kind of load are you hauling? WHat's your tire pressure?

Edwin

 

ya something not right ,10 mpg is what a loaded truck will get.

 

Mine gets 10 MPG pulling 11000 lb. and around 19 empty.

 

Winter fuel will drop you a couple or 3 mpg. Check your star wheel and smoke screw settings. If you are smoking a bunch on take-off, they are set too aggressive. Milder settings will give you better mileage and still not hurt the response.

 

No load. Has always been bad (with the exceptionof one tankful). Tire at 75psi,, Star wheel at 100* CW, stock pin at 120*CW, full load in 1.5 turns, smoke screw flush with lock nut. All needle pointing up straight.

From a dead stop to wot it has a grey could for aprox. 2-3 second and then goes away though all the gears. Only a slight haze on tip in for a about 2 sec.

Its an 89% TC, so that should be a killer, Air filter has about 4000 on it i'll change it down in FL (discount).

BTY: what is the npa BHAF number

 

You're gonna want to take the AFC top off and look at that smoke screw from the inside. Loosen the locknut and back the smoke screw out untill it sits FLUSH with the inside of the AFC top, then tighten your locknut back down. Once you start messing with the full fuel screw, the smoke screw goes out the window and should be adjusted as I suggested. I went thought that with my truck and I picked up some decent mileage just from backing the smoke screw flush. Your description makes it seem like you're tuned pretty well. You can try backing the starwheel out a couple turns at a time for better economy and less haze while running through the gears. Maybe some fellas with aftermarket converters will chime in on how they tune.


edit:BHAF

Fleetguard AH19037
NAPA 2790
WIX 42790
Donaldson B105006
Baldwin PA2820
Hastings AF1012
AFE 20-40044
Carquest 87790
John Deere pmah19037
Big A 93790
Caterpillar 3i0005
Fleetrite ahr819037
Luber-finer laf2531
Fram ca6818
UNI 908

Outerwear cover wr3325-105

 

The star wheel is only at 1/4 Turn

 

from the top or bottom?

 

Got a fuel leak anywhere? Winter mileage, long warmups/idle, and right foot will drop it quite a bit.

 

I would also suggest that you confirm you odometer is not lieing. What do your EGT's look like at cruise? What about your exhaust? mine had some serious crushed sections.

I also wonder if this could be caused by injectors not atomizing the fuel properly(I.E. low pressure, restriction or dirty)

 

1/4 turn down from stock, 600 post turbo @ 65mph. Unfortunately the od is correct

 

I agree that something is not right and everyone concerned has offered good guestions and you have the right answers. You didn't mention which truck you are having problems with. I am going to assume it is the W350. Check your front hubs to see if they are really disengaged. Old dried grease will prevent the spring from pusking out the locking hub even though it says free on the outside. Also on the Warn hubs they use a cheezy piece of teflon strip for a bearing inside the drive hub. This will sometimes dislodge and jam the hub enough to make the axle turn all the time. Pulling the front axle along eats up fuel. Simply jack a front wheel off the ground and turn it by hand while watching the universal at the king pins. The axle should remain sationery unless the hub is engaged.

 

Yeah, its the 93 W350, i know the the front hubs are disengaged. The only thing i could think of is crappy injector atomazation because that one time i got 20 mpg i had dumped in way too much power service grey bottle (half a bottle). I run lucas too as well as power service blue bottle, its what Werner Trucking gives my dad. Since i really don't feal like pulling the diafram cover off again, how far should i back the smoke screw off if it is curentrly flush with the lock nut.

Thanks everyone for your help, I would love to install some POD's and have my fuel mileage jump to like 15 mpg. I really think my stock injectors are done for.

 

My EGT's are 600 pre turbo at 65mph. Around 675-700 at 75mph. Egt sounds a little high for 65mph. I have a 2wd though and taller gearing. Maybe its not an engine problem. You could call suncoast and pick their brains to see if they have any ideas maybe the trans. Something could be causing excessive load.

What about dragging brakes. I would check the temperature at each tire after a run at 70mph. Maybe inspect the brake shoes and pads for uneven wear. What about wheel bearing preload it could be set too tight. And don't forget alignment that could be out even though it drives straight.

I admit I'm unfamiliar with 4wd so I'm just throwing ideas out there. I'm also gonna say if she has some miles on her I'd get the injectors tested, cleaned, etc.

Good luck