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11 Miles per Gallon!!! How to improve!!

7K views 79 replies 18 participants last post by  honestcharlie56 
#1 ·
Im getting 11 miles per gallon.. How can improve that.. Mainly City driving not long trips, 2WD original size tires dually.. on the back I have 4 bfgoodrich all terrain and on the front Highway tires all on right air pressure original metal rims 16inch.. original bumpers, I have a full size toolbox weatherguard.. most of the time its only me and my wife both weight its like 260 pounds... All the front suspension has new joints and shocks and has a metal 1inch spacer on the bottom of the springs... The transmission its working but not that good too much engine sound and does not get very fast.. I think its what its giving me the low milage. I have a s&b aftermarket filter and straight exhaust and 0 plate and the engine its kind of faster at idle. it has less than 3K miles diesel filter and engine oil rotella 15w40. Thanks!!
 
#5 ·
no i dont.. well i dont think so nothing on the floor..
 
#10 ·
how many and which ones and what size of hose are they?
 
#41 ·
Is that like less than a foot "U" shape hose that is like $50 at the stealer?
 
#42 ·
Its like city driving school home work like 15 +/- miles a day or less. Now that I know it give me 11 miles per gallon I like to use my 2003 cavalier jajaja
 
#13 ·
Thats all I can get with new filter,heater delete,stock timming,ok fuel pressure but I think I need new injectors cuz it hazes at idle and it also has a slight miss

Also I do mostly highway driving around 60 mph
 
#14 ·
well i get 12 or so mpg towing 14k. and about 20 driving on the highway.... but its stop and go for miles....

hows the airfilter? fix the fuel lines. you cant see the fuel lines leak. cause it sucks in air. if they are stock lines then they are probally leaking. how do you drive? do you hot rod it? i know you said your trans is out, is it cause of any mods or you hot rodding it.
 
#43 ·
Air filter its clean I even put a wrapper, It probably has stock lines, normal driving it does not get fast only on overdrive(i thing it got fixed before).
 
#15 ·
that terrible especially for a p pump truck i got 15 city on my vp truck stop and go in dowtown traffic something wrong mine was stick though. hmm do you floor it alot check your lines :D
 
#44 ·
even if i try to floor it it the transmission does not respond the way it should, only on overdrive i can floor it.
 
#16 ·
im sorta in same boat. i get about 10mpg. i used to get 16 or so daily driving, but after i put my 35's on it dropped to 10mpg. nothing else changed. o yeh and my trucks got 4.10's which could also contribute to so low, but maybe i have a leak somewhere too. idk????? help if at all possible would be greatly appreciated. thanks!!!
 
#18 ·
1. Your driving in the city
2. Your driving 2 miles so the engine can't be operating temp
3. Your idling more than your driving (5 min), you get 0mpg idling
4. You question your trans, if it is stop and go and it is slipping a lot then of course it is going to get crappy mileage in town if you have to floor it to get anywhere. It only locks the TC in 3rd and 4th. You should never have to go over 2000 RPM irregardless.
5. It is a heavy truck that has to get moving at each stoplight and if you are a stop and go driver it will also degrade mileage. You should coast to the stoplight to the point that it is green by the time you get there, AND take off slowly. You should be able to take off with light throttle and be able to get up to speed at a decent rate. If your TC is slipping really bad to the point that you have to floor it to get anywhere then that is surely the cause of the crappy mileage.

Just watch the RPM's the next time you drive when you stop and see how high they are when you start moving. I am betting you see over 2k every time you take off.
 
#21 ·
3. Your idling more than your driving (5 min), you get 0mpg idling
These trucks dont burn enough fuel to matter idleing

4. You question your trans, if it is stop and go and it is slipping a lot then of course it is going to get crappy mileage in town if you have to floor it to get anywhere. It only locks the TC in 3rd and 4th. You should never have to go over 2000 RPM irregardless.
Stock VB doesnt lock the tranny in 3rd

5. It is a heavy truck that has to get moving at each stoplight and if you are a stop and go driver it will also degrade mileage. You should coast to the stoplight to the point that it is green by the time you get there, AND take off slowly. You should be able to take off with light throttle and be able to get up to speed at a decent rate. If your TC is slipping really bad to the point that you have to floor it to get anywhere then that is surely the cause of the crappy mileage.
trans slipping while the converter is unlocked usually wont be the fault of the converter
 
#19 ·
If the engine starts on the first crank you can rule out an air leak. Logically you can rule out the filter also. An engine can't burn too much fuel if there isn't enough available to start with. Mechanically the timing could be off, and I think someone also mentioned the air filter. The haze you are seeing is $$$. Could be worn out injectors or a leak in the air charge system.

In addition to what Jagger has said, you have a duelly. Driving style and a host of other things cause poor mileage.
 
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#22 ·
If the engine starts on the first crank you can rule out an air leak. Logically you can rule out the filter also. An engine can't burn too much fuel if there isn't enough available to start with. Mechanically the timing could be off, and I think someone also mentioned the air filter. The haze you are seeing is $$$. Could be worn out injectors or a leak in the air charge system.
.
you cant rule out air leaks:confused013:........those hoses wont let the fuel drain down but they will absolutely let air in. An engine cant get bad mileage if its not gettin an adequate amount of fuel.....is that what you mean:confused013:WHAT
 
#26 ·
That is quite a theory.

You realize you are talking about massive amounts of air, right? So much that the engine would have trouble running at all. But he isn't having any starting problems. So where is that air being introduced?
 
#33 ·
the air he was talking about is lots and lots of tiny little bubbles that will infest an injection system when an air leak is introduced. All of these bubbles will then be able to compress in the barrel/lines/injector which will delay the injection event since it will take longer in that cycle to reach the pop-off pressure. That is a fact, not an opinion...this comes from years of working on these engines, not CF, not TDR, not compD. I wish Weston were still on this site and could see the pure BS your spouting off.

Im not aware of it because you still havnt said anything, like stated above, my knowledge of these trucks comes from years of being covered in grease and oil from being underneath them, not a website.

If you have a blockage in the fuel supply causing low FP going into the Injection Pump, the barrels will not be able to fill correctly and the motor just wont run right. Yet again this is fact, not opinion.
 
#34 ·
All of these bubbles will then be able to compress in the barrel/lines/injector which will delay the injection event since it will take longer in that cycle to reach the pop-off pressure.

DING DING DING, we have a WINNER!!!!
 
#37 ·
If you are making short trips, it is probably not ever getting hot. A block heater might help you, just warm up the truck with that before leaving.

Another thing is to check your alignment. You would not believe how bad excessive toe in/out will drag you down. It is not too expensive to have a shop do it for you and not all that difficult to figure out yourself. Here's a good page explaining it: Do-It-Yourself Alignment

Also, not everything on this list will be relavent to you, but there are plenty of good tips that you might be able to use here.
 
#38 ·
Another thing is to check your alignment. .
:doh: I agree mileage will suffer....but the guy is gettin 11mpg. I get 18 pullin 10k down the highway. Plus he would know if his alignment was that bad, tires would eat up in a matter of months and the truck would be all over the place
 
#40 ·
It indeed works the way these guys talking about retarded timing with a fuel restriction say it does-it has happened to me. The 4th fuel filter that at least some of our trucks have inside the pickup assembly clogged on me once. It took me weeks to find out what the problem was. While I was having the problem if I stepped harder on the accelerator it would slow down, egt's would shoot UP, and the white/blue smoke that's classic retarded timing would appear. Those two things, egt's increasing AS THE ENGINE WAS DYING FROM LACK OF FUEL, and the smoke, pointed to retarded timing. I was trying to figure out what the hell the problem was, then it dawned on me-the injection pump can't very well develop pop off pressure in the normal time if the fuel supply is restricted too much. Reaching pop off pressure late IS retarded timing. No further definition or complication necessary-that's it right there.

Regardless, I don't think that's this guy's problem. I'm thinking it will turn out to be a combination of at least a couple of things, one of which might well be a bad torque converter. Hopefully we'll see when he gets it fixed.
 
#51 ·
I was thinking of changing the fuel plate for like a "5".. but really I need to change the fuel lines.. What kind of hoses should i get, how many feet, and what sizes? please
 
#52 ·
Is it better silicone hoses for diesel?
 
#54 ·
Sounds like the tq converter or your trans is shot. Can't hotrod it when it is cold.:doh:
 
#56 ·
I dont hotrod when its cold but something similar, the expressway its like a minute from where I live and have to take it to get to school on time, I have to reach 60-70mph in the morning when traffic its at its peak, It take like 10 min to get to school and the truck based on the gauge its cold!! I feel bad but I cant do anything.. I can not plug it to any external cord because I live on apartments so that not an option... :confused013:
 
#55 ·
Im planning to get a ATS triple clutch converter, regular raybestos clutches, high performance forward band, and some dual oring or something from the transmission internals.. but no money for that yet...
 
#62 ·
Anybody have any idea the size, type and lenght of the hoses needed to change my stock diesel fuel lines... How many in total two(one from tank to P-Pump and the return)? or are there more to change?
 
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