Horrible mileage!!
 

I have an '01 2500 4x4 with auto tranny and get 12-13 on the highway and under 10 around town. I put a raptor 100 fuel pump on (fuel pressure is 19/20 at idle, 12 at wot), adjusted the valve lash, cleaned the air filter, changed the fuel filter, it has an intake, exhaust, edge juice w/attitude. I had it on cruise at 55 on mileage setting for about 250 miles the other day and it got about 13 mpg hand calculated. Not sure what's going on but I'm pretty sure something is f-ed up. Need some other ideas as to what to look at and try and up my mileage.

have you changed the vp at all in the truck? Sounds like you may need a new set of injectors. I would get a set of bosh rv275's they will add mpg you want and a lil power.

^^^^ What he said... How many miles are on that truck? It sounds like bad injectors to me. And when you put the raptor in it was the factory pump lift pump dead?

Truck just turned 178k and I've had it for about 8k miles. The stock lift pump wasn't dead but it was only pushin 8-9 psi and droppin to 1-2 at wot. Where's a good place to get injectors? I'm guessin alligator? haha! I've been needin to make my way over there anyway I guess.

Sounds more like a weak VP44 injection pump.

Do you know if the vp has ever been replaced?

As far as I know it hasn't. The truck is set up to tow and I have a good feelin that's what it was used for before I got it. Don't really what was done to it before I got my hands on it.

Yeah im thinking the vp is weak, but if you are looking for more mileage as well the rv275 injectors would be a good choice as well

Having same problem..vp44 is 16 or 17 at idle..never changed fuel filter or air filter yet dunno wen they were changed. Can that make a difference?..truck is an auto 35s edge ez and bhaf

I'm right with you guys in the poor mileage club, gonna change the fuel filter tomorrow and hopefully that will help some. Getting 10 mpg around town is aggrivating. :dang:

What are some symptoms of the vp44 going bad besides bad mileage?

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And is there an alternative for the vp44?

Low power, possible codes.

The only alternative is an aftermarket (hot rod, monster) which can still fail, or a P-Pump swap from a 12 valve cummins

wow I thought I had it bad.... 12-13.5 no matter how or what road I drive...:argh:

Ive had the stock LP and IP replaced with no change... I think they are out again and going to upgrade this time to see if this helps...

hope we can figure this out:pca1:

even with my compounds and 683 racing all day i never got that low. i dont see a fuel system in your sig hope you have one or you may be losing injection pump. had a buddy loose his injection pump and with new pump get horrible mileage turns out in some cases it hurts the injectors. he swapped out with a set of injectors I had and his mileage was back to normal.

yea it has a fass hpfp lift pump on it. the injection pump looks to be newew also. it has 6/21/11 engraved in the side of it. just filled back up tonight and got 12.6 mpg on that tank. still seems lower than it should be though...

what gears are in your truck? are your tires larger than stock and have you had the speedo reset? That could be some of the issue. How many miles on the truck? Had the valves adjusted at all?

3.55 gears, 285/70/17 coopers, to the best of my knowledge speedo is at factory settings (only owned it for about a month and a half) 261,000 miles. Not sure last time valves were adjusted. How bad is it to adjust valves on one of these?

dont forget big tires and a lead foot kill milage. also if you have 410 gears you cant go over 60 mph without killing milage.

I thought mine was bad!!! I get around 15mpg back and forth to work on the highway with a stock ip and stock lp with 170,000 on the truck its an 2001. installing air dog 150 and edge juice/attitude with the cts this weekend hopefully that brings it up some... let us know what you figure out to be bad

Any more suggestions? Been getting a pretty steady 12.5 mpg lately...:argh:

I'm definitely interested in this problem myself. My truck 2001 2500 4wd auto 3:55's. 230k. 275/65/20's thats about a 33 inch tall tire. The previous owner said he replaced the Vp and the stock lift pump. When I had it off to replace the side cover gasket, it appeared to be a remanufactured one. Starts fine, and runs fine. just ordered an airdog 150. seems to be getting around 14- 15 mpg. Another question I have what should these trucks be getting mileage wise. I haven't been hot rodding mine either.

can cheap injectors lead to the lousy mileage club that I am also a member of? I have a rebuilt vp44 from pensacola diesel, and a set of +50 hp candles from the same vendor. I know when I changed them, she would at least start on the first crank, but could that be my problem? even with the smarty, I have only gotten 13.5 mpg at best.

I am also wondering about injectors being the culprit. Seems to have an extended cranking time after sitting cold for a while. I have absolutely no idea as to what injectors are in it having only had the truck for a couple months and am also a little leary on trying to pull them just for the simple fact I have never pulled injectors on a diesel before. Is this a simple process? Where can I get these pop tested? Also based on the mods in my sig what would you guys suggest for replacement injectors? Thanks guys!!!

We have always got great mileage feedback from our Big Dawg Injectors.

Luke

Any suggestion on which hp injectors? 150hp?

Depends on your mods and how you use your truck.

Luke

My truck is mostly used as a daily driver, but would like to be able to pull a fair size camp trailer or boat without worrying about egts going through the roof.

I would say that 100 hp injectors should be plenty big for that i would think and depending on what your future plans are with the truck but i know that scheid diesel has 100 and 150 hp injectors

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Also I'm not sure if you have a programmer but your mileage may change a little maybe not that noticable but if u do have a programmer and change your tire size and it may go up a half mpg or thats what it did on my truck when i changed my tire size to 33 instead of factory

I wouldn't go any larger than 100hp.

Luke

And I guess if you wanted smaller I think bousch makes a 50 hp injector but I think that 100 hp would be good

I am getting 14.2-14.5 now after I added the FASS and driving normal (for me)....With this tank I just started keeping the rpm's at or below 2,000 and keeping my foot out of it in town. This puts me at about 67.5-68 mph according to my gps (speedo showes 65). I will let you know what I average once I get a few tanks in it.

Well it has been a long time since I've visited and I'm updating all my post I said I would. I am still getting about the same mpg. A little better with the FASS but not near what others are saying (with about the same setup). I am working on my steering issues and wonder if this could cause me to be loosing some mpg. I sure hope so. After that I'm lookaing at the Adrenalin.

Just filled my 01 yesterday. Had 577 miles on the previous tank and put in 29.7 gallons. Come to just over 19mpg.

once you get the fueling taken care of look into the dynatrac freespin kit for hubs. i got another 2.5mpg out of them.

Have a truck at my shop with the same problem. He says it's been going down steadily for a few months now and is at 13ish MPG now. I know of other trucks with the same config that get near or just over 20. This guy says the VP44 and bosch 275 injectors are only about a year old. No codes, no smoke of any kind. Truck actually runs down the road great - real responsive and plenty of power. Going to check the fuel pressure and overflow today. I see lots of these threads all over, but no one seems to be able to solve the problem. Very strange.

i cant help but wonder with 140k on mine if replacing the maf sensor would show a gain

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has anyone ever removed the AC cooler from infront of the intercooler and remote located it with its own fan? i cant help but wonder how much more power and how much more efficient it could be without that infront of my intercooler.has to make for more power and mileage but is it a noticable amount?