Hi'
I'm new to this, but I bought my first diesel a '99 f-350 crew cab 4x4 w/7.3L. The guy I bought it off of took good care of it and told me that he was getting 18mpg.
I filled it up the day I got it. Two day latter and 120 miles I thought I would fill it up to see what mpg I was going to get. To my supprise I only got 10.9mpg. I did this for 2 weeks now, trying one thing after another. I put a bully dog ajustable chip in, which I was going to anyway "wow what a differance" and got the same mileage. I also put a new fuel filter, K&N air filter, checked fuel pump, fuel return line, gas cap vac/breaker and even seems like it has a little less power than when I got it. Yea and thats with the chip turned off. I was thinking maybe a injector suck open, but the thing pers like kittin. If anyone has any ideas please let me know, I'm a open minded person. I just would like to fix it.:help:

I would def get rid of the K&N. If you search the forums around here you will find a bunch of info on filters. The K&N let far too much dirt in the motor and don't really give you any added power.

I am not very experienced with Ford's so I am not sure what to tell you. Have you talked to other with similar trucks to see what they get for mileage. The guy might have been telling you that mileage to help sell the truck. He might have driven differently than you do and had more highway miles. Hard to say, but I do doubt you should be getting that bad of mileage.

Yes, I have talked to other diesel owners and they tell me that they are getting 14 to 18. I'm starting to think that the gas station had bad fuel, I was going to the same place. And my driving habbits are conservitive. I travel 30+- to work and its not in the city its all counrty drivin. The truck only has 72k on it, so I would think that its just broke in.

my fuel mileage has dropped 2-3 mpg since winterblend fuel has came to town, so im sure that is part of your problem.

18 sounds a little high for a stock stroker, they arent the best deisel on the market for milage. with my 01 7.3 i only got about 14 mpg stock at best, usually about 12, with the chip it jumped to 18, but the truck was a crew cab long box dually, the motor's pushing a little more weight. another thing that would be a factor is the arctic diesel, it will effect the mileage abot 2-3 gallons. I wouldnt worry about it too much yet, wait until the weather warms up, then see if anything changes.

Have you tried putting in a new fuel filter??

What was the HP rating on the chip??

GENE

it also depends on your rpms, if your on the highway your gonna get better mpg's from 65-70mph, versus if you were running 70-75 mph. If its country driving then i would stay keep it about 60, and that should give you about peak mpg's i would think.

#1 diesel fuel will yield less fuel mileage and some stations have diesel fuel which yields very lousy mileage. A couple times I've gotten 11-12 mpg from stations that sell very little fuel, the next fill up at a truck stop yielded 16.

If you keep the RMP's under 2,000 you will do ok.

The 99 has 209K miles and still gets 16 in the summer and the 00 has 153K miles and gets up to 20 mpg when cruising around 65 mph.

I took my truck to the Ford dealer to talk with there diesel tech., he answered all the quesions that I had. He also told me that he's diesel (6.9L) was getting 19mpg with 355k on it. He put my truck on the computer and found the truck was 37 update behide, exchaust backpresure senser was bad and adjusted for the tire size (285s) then he put it on the injecter cleaning machine. When he was all done he drove it with his computer hooked-up and said it told him 15mpg city and 18mpg hwy. I drove it to work and back 3 days and that thing was right on the money, I got 17mpg with some stop and start trafic. I have to put the chip back in and I hope that I'll pick-up 1 to 2 mpg more. Yea, let also add that it cost me $608 just to do that. ouch on my wallet.

Sounds like the dude lied to you just to sell it, hopefully he didn't. Just doesn't sound right:confused: