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Things that decrease your fuel economy

R

Rodd

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Okay I know it has been hashed over on various threads but I though we could put a list together of things to look at and in what order. Here I go. Add it and then when we are done we can have a list for the stickies.

1. Leaking fuel filter manager/heater.
2. Corroded/leaky fuel lines.
3. Bad Injectors
4. Failing injector pump? (Not sure)
5. Failing Turbo
6. Turbo oil drain tube not fully flowing (clog)
7. Failing Oil from lack of oil changes
8. Dirty air cleaner
9. Clogged fuel Filter

Correct or add anything I have listed or missed.
 
ALL the above will have some effect.

The mechanical items such as bad injectors, bad injector pump, clogged air filter etc will take the biggest toll on the fuel.

Now this said.

When I pulled the DaHooley down this spring because of the cracked block and glycol poisoning.
The injectors were shot, the oil had at least a couple quarts of glycol contaminating it and the town mileage was still managing to hold onto 17.

Truck has a sun visor and all the no no's and will do 20 Hwy MPG if driven reasonable

At 7000 Pounds empty these sorts of numbers are very good for a rig that is also 22 feet long and is about as aerodynamic as a barn.

All the little things will show up under very controlled conditions.


Missy's take on things

Keep the injectors and IP in good shape
Keep fuel leaks non existant (Fire hazard)
Keep air filter clean (good for the engine and fuel economy)
Keep the oil changed regularly
To hell with the little stuff like visors and other things that make the truck look cool.

All added together the little things could possibly under idea conditions improve economy 1 MPG under best case scenarios.

Dont forget about all the drag you get when its raining. Water on the road causes lot of drag at freeway speeds.

We are talking trucks here and not super MPG bullet cars with no creature comforts.

Just my take on things
 
Agressive tire tread.
Non working lift pump.
Excessively worn Timing chain
IP out of timing
Turbo wastegate control out of order
Winter blend of fuel
 
Missy Good Wench said:
Dont forget about all the drag you get when its raining. Water on the road causes lot of drag at freeway speeds.
Click to expand...

Interesting. Do you have a source for that? I can't think of a single airplane that takes into account runway condition for take off...only for landing or aborting a takeoff. Essentially, standing water is an impediment to effective braking but doesn't increase rolling resistance.
 
Have you ever gone thru a big puddle on the road at speed and had it almost throw you thru the windshield now thats drag.
 
Matt had a good one. When My LP wasn't working I saw about 3 mpg decreas. I have no idea why but I did. Also stock exhaust. GUT THAT KITTY !!!!
 
Mud flaps. Seriously...mud flaps.

I installed mud flaps on "the other" truck that I pulled FEMA trailers with and lost just over 1 MPG on the return leg trips after installation of said mud flaps.

Hard to believe, I know, but mud flaps!

It was at that point when I realized why so many of the professional RV camper pullers were using the removable "hitch skirt" full flap to protect the trailers. This hitch skirt would come off with the ball stinger and could be stored in the bed when dead-heading.

Regards,
 
Okay I've summarized everything and here is what I have come up with. Let me know if I missed anything. Remember this is for those people who recently noticed their fuel economy decrease.



Your fuel economy has started to get worse. Ask yourself why? What have or haven’t you done that can decrease fuel economy. Here are some questions and things you should look at.

1. Is my truck past due for an oil change? Is the oil the proper viscosity?
2. Bad or winter fuel.
3. Are your tires inflated to their proper air pressure?
4. Are your brakes sticking/dragging?
5. Is your soot trap and or exhaust system clogged?
6. Have you added any heavy accessories lately such as rancho bumper, mud flaps, Lift kit, bug deflector, external sun visor, bigger mirrors, winch (not your wife or mother in law :D ), etc.?
7. Are you carrying any excess weight/junk in your truck?
8. Have you replaced your tires recently? More importantly replaced them with larger and/or more aggressive tread such as off road tread.
9. Have your driving habits changed, i.e. more city driving, more idling, are you driving faster/heavy footed, driving w/ windows down, etc.
10. Is your air cleaner clean?
11. How old/dirty is your fuel filter?
12. Is lift pump working properly? What is the pressure at idle and wide open throttle?
13. Do you have a fuel leak (inspect from your fuel tank intake line to the Lift pump, lift pump to fuel filter manager (FFM), FFM to IP, IP to Injectors, IP to return line) and finally is your T-valve leaking?
14. How old are the injectors? Did you test them? Are they good or bad?
15. Failing injection pump. Do you have any DTC’s? Is IP timed properly? What are the IP timing statistics?
16. Turbo oil line flowing (not partially clogged), Waste gate functioning properly and turbine spinning freely.
 
Adding those bumper nutz! I hear the really big "bull balls" will knock off at least 1 mpg.

naw, I'm kidding. But those things are really getting old. The first pair I saw gave me a little chuckle...now that I see em on every other truck - even the little ricers, I'm really starting to dislike them.
 
#1 for me is the winter blend fuel. Minus 2-3 MPG right there.

#2 Slow down. Go 55. :(

In the summer I get between 15.5-16 pretty consistently. But this is mixed city and 65-70MPH when on highway.

By freak accident I got 18 in one tank going slower on back roads on a long trip.

... I am going out on a limb here and will argue the weight issue. When towing my trailer, or any trailer mileage does not drop like a rock as it would in a gas vehicle. Also when hauling heavy in the truck bed mileage is about the same.

Oh, roof rack -.5 MPG.

Meaty A/T tires -.5 MPG (also good for throwing rocks as projectiles)
 
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