I bought a used 2000 F250 7.3L PSD on the cheap to use as a beater truck. It has an unknown number of miles on it as the rear ABS sensor is bad (first on the list to replace), and has a number of issues that need addressing.

First of all, and most important, is the EXTREMELY poor mileage I got while driving it home from the dealer, a trip of about 60 miles. I made it halfway on a full tank. That's less than 2mpg.

The truck seems to run and drive normally, has normal power, doesn't run particularly rough or make any ominous noises. No fluids are leaking and there's not an unusual amount of smoke coming from the exhaust.

Some people I talked to about it suggested that the bad sensor could be affecting the ECU and causing the ****ty mileage. I'm not entirely convinced this is the whole cause, but the sensor is getting replaced anyway so we'll see what happens.

If the sensor doesn't do the trick, what else should I look for? I have no direct experience working on diesels so any guidance you can offer would be appreciated; this will be a learning experience for me.



Given that the mileage is unknown, I'm planning a complete fluid change (engine oil, trans oil, diff oil, coolant). The belts are in good condition so I'm not planning to touch them just yet. The air and fuel filters are also on the short list to be replaced ASAP.

The power door locks aren't working; the button seems to trigger the solenoids, but the solenoids themselves don't have enough oomph to actually lock or unlock the doors. Should I just replace the solenoids? Or is there another possible solution here?

Some additions that I'll be adding soon are a boost gauge and EGT gauge, mostly to monitor the health of the turbo. I don't plan on doing any power mods for awhile, but given the age of the truck the condition of the turbo is suspect and I want to be able to keep an eye on it. For the boost gauge I'll be using the DFUser AIH sensor plug and code override. I live in Texas so the conditions under which the AIH would actually work happen about twice a year.

Any other notorious trouble spots I should check? Any other major issues that could be hiding somewhere in the driveline?

Thanks for your help.

 

There is a quick fix for the door lock actuators here in the forum. A search should help you find it.

As far as the other stuff. I would wait until you've "tuned it up" & replaced the VSS before you start measuring mileage. Could be anything from a plugged air filter to bad math.

 

If there are no fuel leaks when the engine is running, it would be very difficult to get that poor a mileage without lots of smoke. Smoke is unburned fuel, and to get 2 mpg you would be pumping a LOT of unburned fuel out the exhaust.

Monsta is right that you should get the VSS fixed and do a general "tune up" before you get too involved with troubleshooting fuel economy.

Since you say it has "normal power", low boost pressure would normally be eliminated. However, since the truck is new to you, I suggest you check for boost leaks and the condition of the turbo. A cheap gauge T-d into the boost sensor line and tied to a wiper blade will tell you a lot.

 

as far as the air filter do the 6637 mod (very cheap cold air intake that alot of the 7.3l guys have) also another idea ask this in the 7.3 forum

 

Thanks for the advice so far, I'll be checking out the door lock fix and the 6637 mod.

I installed the new sensor this afternoon and topped it off before heading to work, so we'll see what sort of mileage I get over the rest of the week. Fluid changes will have to wait until this weekend, as I'm still living in an apartment and can't work on my truck in the parking lot

Another issue I discovered that I probably should've noticed before: the parking brake doesn't work. I know the parking brake on this truck is basically a miniature drum brake inside the rear rotor, but I couldn't find any way to adjust or inspect it without taking the rotor off. Any advice on this one?

Also, a couple of times the 'water in fuel' light has come on for a couple of seconds, then turned off again. I'd think that if there really was water in the tank, I'd notice the engine running poorly, but so far I haven't. What should I do here?

Again, thanks for all the advice. I know I'm being a PITA but I want this truck to last forever

 

I noticed my 02 SD mileage going downhill, and never noticed any fluid leaking either. One day I pulled into work, shut down and was getting my stuff out when a co-worker noticed fluid coming from under the truck. I couldnt find anything and it stopped after a minute. Long story short... There is a fuel line that is on the R side from rear of engine that is held by a clamp. That fuel line, after rubbing on the clamp for so long had developed a little hole that allowed fuel to fill the valley of motor. When truck was running, the fuel was being pumped into valley and draining via drain hole. When truck was shut off, fuel drained, and I just hadnt noticed. I wish I could tell you more, but A friend of mine fixed it pretty quick as we both had things to do, so I was more of a gopher than student. I may be able to get pics if you need them. Let me know.

Oh, and yes, I wrapped the new fuel line with rubber hose prior to re-clamping.

Hope this helps
Hab

 

Rear e brake is a drum inside the disc. there is a little slot in the drum at the top with a rubber bung in it. You pull this out and use a brake spoon to adjust the star wheel inside, this pushes the ends of the brake pads outward toward the drum like an old style drum (on the bottom more often). The cables go in the bottom and activate an S cam which pushes apart the buttom of each shoe. Like a normal drum, backwards hard stops are supposed to push out the star wheel one click at a time to keep them close to the drum. Given the age, you may need to pull apart and check your star wheels are not stuck, your cables are good, drums are not to far warn so pads can reach, pads still have material ect. Its not hard to do one side at a time, pull wheel, and disk and caliper, re install and then adjust drum start wheel until just touching so you can hear when spinning the disk with one side up. The adjusting spoon, is much like a flat screwdriver but has two sides, wide and skinny and has a 30 degree bend in each end which helps get you more turn of the star wheel under there.

Think of all this as bonding time with your new truck!

 

How about the other possibility - the gas gage is way off/totally hosed, and you thought you had a full tank but didn't?

 

Huh.... So simple, yet probably overlooked......One fill-up while watching the gauge would rule in/out that problem

 

thats what i was thinking when he said 2mpg. could be that the guage is sending slow so it started off at full but relly only had 1/4 tank. mine dose that. but after i'm on the road 10min it all evens out.

 

If you need to do the 6637 mod drop me a line. I have a 6637 kit that will save you some time and money.