Hello all - and thanks for allowing me to join the forum

I have had this 2000 F250 7.3 Powerstroke with 4:10 gears, and the 6 speed manual gear box since it rolled off the show room floor and it has been a wonderful hard working piece of equipment for me. But now I am experiencing excessive fuel consumption and a lack of responce.

I used to be able to load the truck with 800 lbs of equipment -plus my 3 sons and all of our personal stuff, point it at Seattle Washington on I-5 (1500 miles) punch in 70 mph on the cruise control and average 19.3 mpg.

Lately I ran 2000 miles unloaded to Beaumont Tx. just me and my clothes, driving 75 mph pretty much the entire distance and averaged 14 mpg. Additionally on the way back (2000 miles) I was hauling a 24ft 5th wheel GVW 8000 lbs and averaged 12 mpg running between 55 - 65 mph the entire distance.

I know the Injector O-rings and Glow-plugs are long over due for replacement but it seems like there must some thing more involved then that. When the truck is warming up and the ECM ramps up the idel speed I can hear some thing in the exhaust "searching" and cycling the exhaust. No it is not blowing any smoke White or Dark, and when it has the cruise control set at 65 mph towing the 8000 lb trailer the engine has a nice warm purr to it

Any comments thoughts and which direction I should take

I have the O-rings and Glow plugs on order and plan on replacing them before I take it into Fleet Service for the Diagnostic Check.

 

Personally, I would start with the turbo, check the wheel for wear, shaft for play. Check the air filter, fuel filter. (How old are they?)

Check your inter-cooler boots for leaks/wear. Check your up-pipes for soot (indicates leaks.)

Also, you can check your EBPS and clean that up: Welcome to guzzle's Exhaust Backpressure Sensor Cleaning Maintenance Web Page

You hand calculating all the mileage? Any chances you filled up with winter fuel? (D1 vs. D2?)

 

The exhaust 'cycles' during warm up creating a whoosh-whoosh sound. I have the 7.3 with 3.73s and the automatic and I average 15.5-16 mpg empty running 65 on the highway. I would say that you are inline with your numbers.

 

So are you saying the 14 MPG at 75 mph is correct for my truck. I should have mentioned in my original post my F-250 is 2 Wheel Drive

Automatic Trans and 4WD from my understanding 15.5 - 16 MPG is right in line from everyone I've talked to.

 

When you say you were getting 19mpg, how did you calculate it? How are you calculating it now?

 

By hand at the gas pump "Miles / Gallons"

I kept a record all the way from Beaumont resetting the Trip Odemeter each fill up -

 

Just wanted to make sure.... many use the overhead computer, which sucks.

 

Another common "issue" would be the caliper slide pins freezing, causing dragging brakes.

 

I would say you made a good call on the Intercooler Boots and the EBPS - at least that is the direction I'm heading now

BTW: my qualifications are I own a machine shop but work mostly as an Instrument Technician in oil refineries - pays better then competing with Chinese manufacturing

 

Moved to the 1999 - 2003 7.3L Powerstroke Diesel forum.

 

14 MPG with 4:10's at 75 MPH sounds about right to me, that puts you spinning about 2300 RPM . You are probably losing some MPG due to winter fuel are you running stock sized tires or something different ?

 

+30% reduction in MPG for 5 mph increase ??

Sounds a bit of a leap. As I stated in my Op I've run the truck with cruise control set at 70 mph over 1500 miles and achieved 19.3 mpg. I only slowed down for Medford - it's a speed trap.

There are other symptoms as well. The responce is not a snappy as it once was.

 

I am really screwed then. I pull a little 14ft enclosed trailer and these days I am glad to see 10mpg. Guess I need to follow some of these tips as well. Keep em coming $40-$50 a day in fuel is getting expensive.

 

I would check the items that tomang07 listed. Those are pretty common failure issues and can only help you.

Something else to consider is that the fuel recipe has changed since you bought the truck. I am not sure how far back you were referring to on the 19 mpg but I have noticed every older diesel i drive has fallen off on mpg since the introduction of ulsd.

That may not be it but something I have noticed. I remember hearing at the time it came out that it should maintain within 1% of the original mpg but it seems to be more on most things.