Some of my recent 7.3 PSD mods...
 

Apparently, over time, the Fuel Pressure Regulator (FPR) screen has an orifice that gets loaded up, and that results in lower MPG. I got a new screen to replace the old one, as I'm assuming that it's original with 252k on it.

Additionally, I shimmed the spring for the FPR. Supposed to improve idle, some noise problems, maybe help out too on the MPG side? Unsure, but it might reduce some of the air that can get built up in the fuel system, and that can improve combustion.

Replaced the fuel filter while I was there also. I am now on my "rinse" phase of the product Auto RX also. Again, with 252k, I'm hoping that the inside might need a long, slow cleaning that Auto RX is supposed to provide. The cleaning phase takes about 2500 miles, the rinse phase takes 3000. Might go ahead and run a second clean & rinse after this.

Mileage has been on a downward drop for a couple years, and I have never dropped as low as it has been this year. I'm hoping some of these issues will bring it back up, or show me that some of the local biofuels are causing me some reduced mileage.

My guess is that your fuel injectors a pretty worn. If they've never been rebuilt, that could be the major cause of your steady decrease in economy. I have about 245K on my 96 PSD and I have never had mine rebuilt. I've been resistant to upgrading mine to some schmancy hybrids along with a modified H2E turbo. I have a straight downpipe (no cat or muffler) and a Tymar intake. I haven't shimmed the FPR yet.

I doubt the biodiesels are causing a mileage drop. If anything it should go up. I have been running B20 for about 6 years. Sometimes I HAVE to get #2 diesel, and I really hate how it runs with it.

Replaced the ICP sensor and the BARO sensor a few weeks ago. Mileage went up and was right in the ball park from years ago. Disconnected the EBPV also.

Now, I'm just getting back from my latest trip, and everything hit the fan. Lost the power steering, and then the smoke started again.

Injectors? Yeah, I agree. There are plenty that have replaced them earlier than 256k where I'm at.

Took a look at your gaslog, and the E350 van gets about 11 mpg. I was feeling bad that my F350 gets about 18 mpg. I feel better now. You should trade the van for a pickup.

Yeah, but my bus outweighs an F350 dually by 2000#, and I'm pulling a trailer with a dry weight of 4000#. Loaded up, it's probably a total of an easy 15k+, depending on how much gear and bikes we have in it.

Oh, and don't forget, the bus is 9.5 feet tall, the trailer is 8.5 feet wide. Lots of aero issues.

11MPG is bad, but that seems to be related to some old sensors that are going out. I used to get a regular 13 pulling everything. Starting to come back up now. Might have it sorted out.

The cost of the bus for me was probably a fifth the cost of a pick up with the same mileage, and the insurance for the bus as an RV is around the same ratio. We sleep three comfortably, regularly in the E350. I can't do that in a truck.

Gotta compare on equal ground, right?

I have an 03 Excursion 7.3L diesel with 50K. At 36K I chipped and converted the intake with the Ford kit. My mpg shot from 15 to over 20 mpg. I tow a 30ft trailer (8000#) and get over 12 mpg instead of 10. What else do you suggest for minor alterations?

I'm moving into an 03 X with a 7.3 this week. I should be asking you?

I really like the 203 degree thermostat. I think I'm going to do a DP Tuner chip set up.

You have the Ford intake kit? I've been thinking that route myself.

7.3 turbodiesel
 

The Ford intake kit is over $200 but pays for itself soon at $4.75/gal fuel. It installs easily and the truck breathes easier. Try to find the filter on the internet, Ford wants $110!

E350 problem is injector under valve cover wiring. Need to get some time to get the valve cover off to repair everything that's wrong there. Excursion is going on longer trip tomorrow. Won't have time to get the chip on the ECM before then. I guess I'll get a chance to test the X stock.

That's a common problem with them. When I was the vehicle officer at the rescue squad I had one truck that would eat an injector harness every year. It was expensive too. I was glad to finally retire that truck. I always thought it was a poor design to make the wiring harness integrated with the valve cover gasket.

-Jay