When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Greetings gang. I just found and purchased a '74 F350 SCS with 72K miles (390 2bbl, A/C). It had been stored in a barn since '02. Let the restoration begin!
Needless to say, the fuel smelled like turpentine and after putting a bit of good fuel in each fuel tank, she started up and ran long enough to get her home to my shop. That ended with both the fuel pump filter and in-line filter getting clogged up with sediment, rust flakes and whatever else to the point where she is now starved for fuel and the tanks are obviously filled with crud.
So, the question is this: do I remove the existing tanks and have them cleaned, then reinstall? Or is it cost effective to just replace the tanks? If cleaning, can someone suggest a procedure? If replacing, where is the best place to purchase an OEM style tank?
Tanks can be dropped from below. Pulling the box is not necessary. That said, its easier w/o the box... and if you are planning to clean and paint the frame, good time to do it before the tanks go in.
OEM Fuel sending unit possible locations?
76-up F100-350 >s/n C00,000
Use with aft axle steel tank, includes gasket
D7TZ-9275-D
Bob Hoover Ford-Mercury, Vienna, IL (618) 658-9218
Brighton Ford, Brighton, MI (800) 336-3305
Beau Townsend Ford, Vandalia, OH (937) 898-5841
Own Ford, Jarratt, VA (434) 535-8515
Vintage Fords, Beaver Dam, WI (877) 846-8243
Sending unit test and then a tank drop procedure that works for me: Disconnect the wire that goes to the fuel sending unit at the tank. Ground that wire to the frame, making sure the frame is clean. Turn the ignition to the "run" position and watch the fuel gauge. If the gauge swings all the way to full, either the sending unit itself is bad or it has a bad ground. If the gauge stays on empty then either the gauge is bad or there is a wiring problem.
To pop the plug off for the test, you can barely get up in there with your head and see the plug. While looking at it, VERY CAREFULLY use a screwdriver to pry it off. AND I MEAN VERY CAREFULLY. It is only pushed on like a 1/8". This is only if you can’t get it with your hands. Once you have done the test (above) and decide it’s the sending unit. And you have cleaned the ground and that did not work. Then disconnect the ground again and fuel line and read on….
If you can't get either one disconnected, no worries you will have a little more room once the tank is dropped down a little. But make sure you have some wire slack in the plug connector. Run the tank dry or almost or siphon it empty, I would not do it with ½ a tank of fuel, but if you just have to, just use a big floor jack and a piece of 2x2 plywood. It’s not heavy at all, unless you have it full or 1/2 full of gas. DRAIN THE TANK!
Loosen the filler and vent hose clamps at the tank end and maybe you can pop the lines off? But most of the time you have to just loosen the clamps and wait till the tank is about out. With the jack in place, or not, just loosen the hdwr (2 bolts) on the front straps, and remove the tank straps aft hdwr all together, then swing the straps out of your way.
Slide the tank to the dvrs side about 1/2" and then pull out or let the passenger side come out of the frame. Then disconnect the elec connector and eng feed fuel line if you could not get to them earlier.
Then slide it as far as you can to the right and pop off the filler/vent lines. Sometime you need to carefully put a flat tip screwdriver in between the rubber hose and the tank to break it loose. The filler neck and vent lines get stuck to the metal pretty good sometimes.
Once the tank is removed there is a lock ring that comes off with a screwdriver or punch, look for a small tab that has been bent over to lock it. Un-bend it, tap off the lock ring, remove the sending unit.
Insp the underside of the tank where the support straps rest, lots of dirt and moisture build up there, and that causes the bottom side corners to rust out. You can also come reinstall time replace the anti-chaff material. Old 2" ratchet strap work great, glued to the support straps, but they can hold moisture so use strips of rubber. Use a Poly tank and no rust worries.
Insp the inside of the tank, might be a great time to replace it all together? Before you reinstall anything connect the electric connection and ground to the sending unit. Wire it up under the truck so it is not hanging by the connection. And with the key in the 1st (on position) you should be able to move the float arm and see a difference in your gauge?? It is always easier to do this with a helper.....
Also before install, paint the complete top, bottom sides of the tank with some good paint. Even spray on bed liner or undercoating??
Nice write up. Only thing I would add is be carefull with the poly tank. I am still fighting leaks out the sender gauge gasket on my poly tank. I might go back to steel and upgrade to 25 gal at same time
Although some fuel-rated O-rings fixed this for me, if you really want it sealed up well, there are plenty of great sealants out there that won't let you down.
I just replaced the entire fuel system on my Scab because it was sitting for over a year with alcohol gas in it. New fuel hose, tank, pick up, pump and hard lines were only $300. It'll be YEARS before I have a fuel related issue and that's the way I like it to be.
