Hey everyone,
Back at you all with another question (what else is new)!

I have my tank pulled to do what I thought was a foot replacement and the hutch/harpoon mod, and have found out I am in a bit deeper than I thought. I pulled my sending unit and found this:


The brown just wiped off, but the mount for the float's resistor being rusted (with the smallest hint of rust in the fuel neck) leads me to believe that water, at some point in time, has entered the tank. When I replaced my fuel filter a couple hundred miles ago it was quite the sight, with what I could see in the fuel bowl looking rusted. This is what made me think something was amiss in the tank, but I was hoping it was an incorrect hunch.

I ohmed the sender out, and got some, I suppose interesting, results. I was unable to get photobucket to correctly upload my video, so for now I have put it into a shared album on my Google photos library. CLICK HERE TO SEE. I will attempt to either embed or attach it here when I am not running on fumes at 0300.

I looked in the tank and didn't really see anything to be growing. Do note that my phone took some odd colored photos here, the fuel is actually the color of the fuel on the left in this picture (original diesel left, r3 right. Image courtesy of BIO HITECH ENERGY | Hydro-Refine Fuel Processing System | Ground Breaking New Alternative Energy).


My tank:



IMO it may be something simple that I have just missed, I haven't been myself lately. Work and classes have taken a lot out of me lately.

 

I wouldn't let a little bit of surface rust bother me as long as it's not severe. Water in the tank would be on the bottom and would get sucked up and prevent the truck from running. Oil floats on water, not the opposite so it's not like you had a film of water on top of your fuel which in turn caused the rust. While it's apart there are some sort of filters inside that contraption that need to be cleaned, or even removed if you add an external in-frame filter as part of your project. Others will give you specifics on it.

 

You didn't mention mileage on the truck, I just did the Hutch mod on mine at 242k miles and I have no desire to drop that tank again any time soon.

For that reason, I would probably replace it while you had it apart to ease the mind, but those are pricey. You might check the local craigslistings for someone parting out a 7.3 and see if you could find one that way.

 

Here is a link to the Racor PS 120 that most have settled on as the replacement pre-filter before the pump. You put it in line on the frame rail, prior to the fuel pump.

http://racorstore.com/racor-ps120-02...ewUaAvGT8P8HAQ

Here is a write up on the whole Hutch & Harpoon mod as we call it.

Welcome to guzzle's In-tank Hutch Mod Web Page

 

The truck has 360k, and I can understand why you have no desire to drop it again. It isn't that the tank itself didn't want to come out, the fuel filler neck was stuck on the hose and took about two hours of stretching the hose to get it off.

Thank you for that link to the filter Jason, I will be getting it to the shop pronto.

Now my question is: Has anybody successfully R&Red the resistor assembly itself, replaced just it, or will I just need to eat the ~$350 a complete unit costs? I do know some people have stated you can get just the float/resistor assembly out of a 6.8 and use it, but those threads never seemed to show a clear answer if it worked or not. Looks to be Motorcraft PS82 (F81U9A299FF, F81Z9A299FA)

I now realize this morning (er, afternoon actually) that I didn't state the root cause of my drive to drop it: My fuel gauge was reading full until about 300 miles, then would run out at 1/4 tank. I thought my pickup fell off, but upon dropping saw it was still in tact, just with a rusty screen. I ohmed out the float, and in the full position would get a flash reading of 150-165, then the resistance would sky rocket. In the empty position I could not get a flash reading but once, and unfortunately cannot remember it. I finally got readings when I switched to 20MΩ with readings anywhere from I believe 4.5-6.5 with float in the full position.

Thanks in advance for yall's help!

 

As far as the sending unit, I am lost on that. I would probably look at picking up a used unit from a salvage yard.

 

Well, no luck on getting one used. All the salvage yards I know of around here didn't have one available. I might try and crack open the resistor unit itself and see if I can get it to read correctly before I drop the $350 for a new one. I would rather not purchase the $150 sensor itself from RockAuto or similar only to find they aren't compatible.

EDIT:
Turns out I found why I am not really getting a definite/correct reading off the resistor. When looking at it through the float arm assembly it is cracked. Welp, if I cannot find a new one looks like Rockauto will be getting a chunk of change from me. $350 is a lot better than the $600 Ford wants.

 

Have you tried car-parts.com yet? Might find one close that way, or someone willing to ship one. I just looked and there are a couple in the $80-$100 range here in TX.

 

I'd dump a bottle of in there when you're done with the full-bore Hutch and Harpoon. No expert here but it looks like unwanted life was clinging to your pickup tube in hopes of finding land and evolving vertebrae.

Any chance at a pic of the cracked sender?

 

I couldn't seem to find one within the immediate states around me. Hopefully the part I ordered will fix it. Worst case I may see about one farther out and see if someone would willingly ship as you suggested.

I may just do that. I had been running a regiment during the winter but have since stopped. Guess I oughta start back up! As far as a picture goes I will grab one once I dig back into the unit. I ordered Motorcraft PS82 and hope I can switch just the rheostats over. Worst case I can fashion up a mount for the entire assembly. It will be said I do plan to document it so if it does work and works well, I will share the results to help others in the same boat as I am not have to spend an extra $200 for the entire unit.

 

I skimmed this quickly.
Is the gauge working, if so, ......

Mine had a rusty appearance back in 2010 (6 years and counting). I did not replace it, still working.

 

I thought I saw a sending unit on rifff raff's web site.

 

The gauge does work, just would read full constantly and would eventually decide to drop lower - if I held my mouth right.

I did see the one on Riffraff's site, and was considering getting it if it came down to it. Would I ever use the amount of fuel it can supply? More than likely not, but with it being just a tad bit more expensive than the Motorcraft unit, I would get it simply as it is a bit overbuilt for what I would do.

On the plus side, I got the new float swapped over and installed in the tank (with the Hutch & Harpoon mod done). I will hopefully get the tank completely installed tomorrow morning before work, and if all goes well plan on sharing the methodology with everyone here!

 

My fuel gauge reads like that, it happened literally overnight, one day it was reading fine (low fuel light had just come on), the next day I filled the tank & the gauge stayed on full for the next 300 miles before it slowly crept down. At around 450 miles it was showing just over 1/4 tank & I filled it up again, it took as much as I've ever got in there. I've been putting off dropping the tank until I have the time & inclination! Keep us posted on how it works out.

 

Before dropping I would try hitting the tank with a rubber mallet around the area where the sending unit is (on the sides/top). Almost sounds like your float got stuck up in a wire. That is what I thought was wrong with mine at first, but when I couldn't get it to change the reading I decided I would only go 300 miles before refilling. Now since I had the driveshaft out I went ahead and fixed it up. Works like a charm now!