75 F-100 short bed 4x4 390 - 19 gal Tank behind the axle

Noticed some fuel dripping while refueling today... Looked up the filler tube and it doesn't seem to be readily available through the regular sources... Only NPD, MAC's, Carpenter, & LMC... My concern with these is quality. Can anyone vouch for them or suggest alternatives. My guess is ethanol has eaten the rubber and rather not replace with something else that will melt if possible.

Also, I didn't climb under there to look... What all is involved in changing this? I hope there is enough room to work without dropping the tank.

Lastly - Any other suggested items to address/look at while working on this? The fuel system otherwise seems to work as it should but was thinking it might not hurt to just go ahead and change all fuel lines.

Thanks!

 

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Comments added below in red. Note, now is the time to go to a 38 gallon tank, if you have thought of it.

 

I just replaced my fuel filler lines last weekend with the LMC parts. I thought the quality was fine, it also came with an external metal bracket that protects the fuel hose from rubbing on the frame. It is too tight to work under the bed where the tank connections are so your best bet is to drop the tank. While you are down there I would just replace everything, like hoses, fuel sending unit, just do that job once.

 

I just installed the LMC hose. Quality seemed OK... time will tell. As posted, it can be done with the tank in place but not easy. Helped a lot to dismount the filler assembly from the bed side ('78).

One thing to check... the leak could be caused by loose hose clamps. I had that situation once... and extra turn of the clamp stopped it.

 

Thanks for the responses... Not sure I will be able to do everything suggested (unless needed)... This truck has a few other critical issues I need to resolve as well and $$ only stretch so far. It doesn't hurt to try and tighten the hose clamp a bit so I will try that first but gonna keep my eye on it as it hasn't been an issue until now; no maintenance has been done there in as long as I have owned it. If that doesn't do it I am gonna have to drop the tank to see what I am dealing with. Anything critical or cheap will be dealt with but not sure I can take care of the desirable but not absolutely necessary at this point. Will keep this thread updated until resolved.

 

To be sure, the most expensive will be the filler hose. The rest of the stop will cost maybe $20 total. When I changed my rear tank, I replaced all the stuff we mentioned. I bought rubber sheeting and bolts at the hardware store. The others are the clamps and fuel line, prolly about a foot of each.

Good luck when you do it and do it with an empty tank, if possible.

 

I got the 2-1/4" filler hose and 3/4" vent hose from Filler Neck Supply Sells, Gas Filler Hose, Fuel Filler Necks They sell heavy duty "aircraft-quality" hose by the inch, each piece I ordered 15" long and the whole lot cost $30 including delivery.

As for removing the tank, drop it from below (as long as you don't have anything else in the way) when it's as empty as possible. Disconnect the fuel line and float connection running forward from the front of the tank

Attach the new hoses to the tank first, then re-install.

To re-install, I used 2 ratchet straps to slowly raise it part-way, feed the hoses between the bed and frame, then continue raising it further. The ratchet straps will bind after a while, so use a couple of ordinary cam-lock straps to hold the tank while you reset the straps and start hitching it up again.

The ratchet straps take a while but it's an easy one-man job.

Hope this helps, good luck.

 

Well I finally got around to working on this... I am surprised the truck even ran as the fuel line pulling from the sending unit was rotted through as well. The sending unit wasn't in the the greatest condition either. Glad I went and just dropped the tank all the way; it really wasn't too bad of a job... a few hose clamps and 4 bolts. I used a tranny jack sitting on a milk crate to lower it.

Here are a few pics of the job thus far:

This is the main culprit of the leak... Right at the bottom of the filler tube.





The filler vent tube wasn't in much better condition



The sending unit had at least partially come apart... Those three little bits to the left of the sending unit had been bouncing around in the tank for some time it would appear. I think they all had originally been a part of the sending unit; the black piece fits right on the end so it must have been the pick up which means this thing was unable to pull up about 1-2 gallons of fuel that was in the tank.



Some new hose and clamps to replace the old stuff... Still need to cut. These are all the parts I was able to source locally. The rest the parts stores have to order but I can find cheaper myself online. The big 2-1/4" hose is normally about $20 a foot (way cheaper than $50 for the application specific hose I found online) but the guy gave me a break since he had this 18" piece already cut; I paid $24 for it, about $12 for everything else, plus another buck or two in taxes. It is all made in the USA and really high quality so this approach was meant to be. I will cut to fit when I get around to installing.



So aside from the sending unit which is about $40 on Rockauto ($20-$40 cheaper than anywhere else) I want to replace the sending unit wire harness and the vent/grommet... Need to source this and order as a next step.

 

Aside from being dirty the tank itself seems to be in good shape. I am going to clean this up, the surround areas, and associated parts/hardware before painting. I figure I can do this while awaiting the parts in the mail.

 

Good progress. One thing to check is diameter of the fuel pickup tube. OE on most Dents was 3/8". Commonly available re-pops are 5/16". I used a 5/16" on mine and had fuel starvation at high load. I added a small electric booster pump just in front of the rear axle to fix it.

 

Just checked... 3/8"... cut to fit. Thanks for the heads up cause that would have been a real headache.

 

Way to follow this through. Don't forget new rubber for the straps.

 

Fuel filler tube is steel, fuel filler hose is neoprene rubber. I doubt the fuel filler tube itself is leaking. Over time, the hose expands, begins to crack.

390's were not factory installed with 4WD

 

Had to replace electric fuel pump in my daughters Expedition twice called Ford 2nd time quoted me at least 1000 dollars,,,so I removed it in 20 min and replaced it a second time,,,pay yourself a 1000 dollars for a job well done You can do it! good thread with good info Your bed looks to be in good shape