Bad fuel tank selector valve??

[Adam M]

Hey everyone, "I'm a long-time viewer" and first time poster so please go easy on me!

I am having an issue with my 7.3 IDI leaking fuel from the tank selector valve. Seemingly whenever the rear tank is selected.
I primarily use the front tank because its new and doesn't leak but I feel like this issue needs to be addressed.

My internal debate is whether or not to replace the selector valve or to bypass the unused back tank completely.
I like the idea of bypassing the back tank because I have no intent on using it anyway.

Any recommendations or diagnosis? It leaks a significant amount of fuel, like I said, right at the selector valve.

 

[Zaggnutt]

I am switching to manual tank selector valves as soon as eBay mails me the rest of my parts, but I bypassed the rear tank so I can use the truck without the FSV. Bypassing is easy, took about 1.5 hours to do the work. A razor knife, a pipe cutter, some diesel rated 3/8 and/or 5/16" rubber fuel hose, some hose clamps.... voila!!! No more FSV!!! Tip: Beware the Diesel Bath....

As far as diagnosing the FSV, you will have to drop the front tank guard and get in there and take a look. 6 lines total, 2 from front tank, 2 from rear, 2 to the engine. The larger diameter line is the feed (3/8") and the smaller is return (5/16") Go to page 5 and scroll down. There is a pic and diagram.
http://www.oilburners.net/forums/sh...ightmare/page5&highlight=manual+tank+selector
The selectors get clogged by debris from the in tank filters coming off and getting sucked into the fuel line.

 

[Adam M]

AWESOME!

I am switching to manual tank selector valves as soon as eBay mails me the rest of my parts, but I bypassed the rear tank so I can use the truck without the FSV. Bypassing is easy, took about 1.5 hours to do the work. A razor knife, a pipe cutter, some diesel rated 3/8 and/or 5/16" rubber fuel hose, some hose clamps.... voila!!! No more FSV!!! Tip: Beware the Diesel Bath....

As far as diagnosing the FSV, you will have to drop the front tank guard and get in there and take a look. 6 lines total, 2 from front tank, 2 from rear, 2 to the engine. The larger diameter line is the feed (3/8") and the smaller is return (5/16") Go to page 5 and scroll down. There is a pic and diagram.
http://www.oilburners.net/forums/sh...ightmare/page5&highlight=manual+tank+selector
The selectors get clogged by debris from the in tank filters coming off and getting sucked into the fuel line.

Thanks so much for the info! I'm writing this down now!
So I guess the best way to get the work done is drop the tank rather than remove the bed?
Some people I see on these forums argue that removing the bed is easier than dropping the tank. Would that be a better option?
My work space has no lift whatsoever, this job will likely be me, my friend, and a Saturday afternoon in the driveway

 

[icanfixall]

Welcome to the forum. Why drop the tanks or lift the bed to reach the fuel tank selector valve. Not needed for any work on the FTSV ever. Now if you have to open the tanks to clean out the broken suction shower heads then even that not needed. You can easily reach the front tank sender_suction head unit. Its all part of the level indicator and lifts out with plenty of room. Just clean off the dirt from the cover area and remove the lines and wires. then a punch or screwdrivers and hammer to knock loose the ring. Watch the gasket and the alignment pin in the tank top when you install the sender level suction head. Now the reae tank requires you drop the tank or lift off the bed to reach the sender mess but.. Make sure you cut loose the lines that are attached to the frame cross member near the differential. This allows more room to drop the tank so you can reach in and remove the 2 lines and the wires from the sender. Doing this with fuel in the tank is ruff because it sloshes around causing a balance issue. Remove all the fuel before you reinstall the tank. You might try replacing the rubber gaskets on the fuel tank selector valve lines too. Most auto partsd sells the seals or go to any wrecked ford truck and remove them from the lines at the valve. All the fuel supply and return lines have special clips that secure the lines to the valves and the tanks. they are 2 different sizes too. supply is 3/8 and the return is 5/16. they are different colors too. you leak might just be a bad seal or a missing clip.

 

[Zaggnutt]

Yeah, x2 on what icanfixall is saying. Don't confuse the FTSV (fuel tank selector valve) with the Sending Unit. The FTSV or FSV is mounted to the frame rail right beside the front fuel tank near the front end of it. The sending unit is the fuel pickup and return unit in the tank. Have some sort of diesel fuel catcher rigged up before removing the lines and a screw or something to plug the lines with. The pickup side of mine continued to drain til I plugged it. The clips icanfixall mentioned run through the "quick connects" on the ends of the fuel lines. It is a plastic clip shaped like a horseshoe with a wide flat piece at the closed end you can stick a screwdriver blade under to pry. The open "legs" have a barb to hold them in the quick connects. These should be removed before removing the fuel line. If you are trying to reuse them (I did) you need to push the clip in an through to get it started. Otherwise break the legs off and remove them and get replacements from autoparts store. Just keep in mind the quick disconnects should come off fairly easily. There is an oring in there and it is going over metal so too much muscle and you can tear or otherwise damage it.

 

[Zaggnutt]

A lot of this information will make a TON more sense once you are under the truck looking at everything. Just get on your back near the front end of the front tank and slide your head under. You'll see what we're talking about.

Keep us posted on your plan of action. If you are going the bypass route, you will want to remove the tank guard to access the sending unit, BUT you only need to remove three of the four nuts/bolts... The inside front nut/bolt is a pain in the ascot to remove and doesn't need to. With the other three out you can lower the shield onto a block or something and you will plainly see the top of the sending unit that icanfixall referred to. Just a tip: The sending unit is on the passenger side of the tank and cannot be seen from the driver side with the tank still strapped in.

 

[Adam M]

Thanks guys! Yes its definitely the FSV. I also have a bad sending unit (at least a bad anti slosh device, needle is all over the place) so my goal is to completely redo the fuel tank set up. I want to completely eliminate the FSV and Tank switch, and get rid of the rear tank completely. I have a buddy whose gonna help me once I get all the parts, probably next month after the 1st.

So the parts I'm getting are 5/16 and 3/8 diesel rated tubing, tube cutter, some hose clamps, a new sending unit and fuel filter (I still have the leaking one). I have the diagram of where the hoses go, thanks again for that, and I think thats it?
Does that look like all I need for this project? Yall are sure bed removal for all this isn't necessary? And on a side note, anyone wanna buy a used rear tank??

Thanks again, yall are super helpful!

 

[Zaggnutt]

Thanks guys! Yes its definitely the FSV. I also have a bad sending unit (at least a bad anti slosh device, needle is all over the place) so my goal is to completely redo the fuel tank set up. I want to completely eliminate the FSV and Tank switch, and get rid of the rear tank completely. I have a buddy whose gonna help me once I get all the parts, probably next month after the 1st.

So the parts I'm getting are 5/16 and 3/8 diesel rated tubing, tube cutter, some hose clamps, a new sending unit and fuel filter (I still have the leaking one). I have the diagram of where the hoses go, thanks again for that, and I think thats it?
Does that look like all I need for this project? Yall are sure bed removal for all this isn't necessary? And on a side note, anyone wanna buy a used rear tank??

Thanks again, yall are super helpful!

For the hose, if your steel fuel lines are in good shape then all you need to do is cut off the 2 quick connects at the front of the FSV, add the 5/16 to the return and the 3/8 to the send and run it along the frame rail back and then up and over the tank. Disconnect fuel line there and slip the new line over each metal elbow. It's about 3' of hose for each. Done.

Now, if you can only run the tank down to 1/4 before running out of fuel or you are dead set on removing the sending unit in the front then there is more to it. If you are going to be pulling the sending unit then you will need to remove the tank guard completely. I would recommend removing the tank and thoroughly cleaning it out if you are going this route but as icanfixall stated it is not necessary. I just wrote a detailed description step by step of the procedure for dropping the front tank. Let me know I'll post a link to the step by step and post some pics for you too.

Just a side note here - it's possible the fuel gauge issue is related to the FSV issues. The tank float is a little metal arm with a metal cylinder attached to the end of it floating in the tank. There is a circuit attached that runs up to the top of the sending unit and then out to the FSV along with several other wires so not much to go wrong with it. Google "7.3idi sending unit" and you will see what I mean. There isn't much to them. Mostly just metal fuel lines attached together. The intake has a plastic filter on the end that looks like a little shower head and the return has a little red duck bill check valve.

 

[Zaggnutt]

You are going to want to run some compressed air through the lines with the sending unit disconnected before you attach hose just to be sure the lines are clear. I would wait until just before you connect everything up to be sure nothing falls in at the last minute.

 

[Zaggnutt]

Bed removal would make things much, much easier if you have access to the necessary equipment but it can be done without.

 

[Adam M]

I will definitely keep yall posted. Keep in mind this will be a next months project so It will be some time, I will start ordering parts though.
Thanks yall! So greatful for your help!

I will get down under there tonight and snoop around a bit and do some recon work!

 

[Zaggnutt]

Check this thread out...
http://www.oilburners.net/forums/sh...Top-Of-Sending-Units&highlight=fuel tank leak
scroll down to the pic. That is the sending unit on the front fuel tank. The pic is taken from under the middle of the truck facing out.

 

[Adam M]

Check this thread out...
http://www.oilburners.net/forums/sh...Top-Of-Sending-Units&highlight=fuel tank leak
scroll down to the pic. That is the sending unit on the front fuel tank. The pic is taken from under the middle of the truck facing out.

YES! That helps alot, thanks!!

 

[Zaggnutt]

Pulled my FSV and rear tank today....

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Rear sender (minus shower head filter)

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I just did a long, pic heavy write up on removing the rear tank and sender step by step. It's here:
http://www.oilburners.net/forums/showthread.php?67956-Shower-Head-Rear-Tank-Removal

 

[Adam M]

WOW!!! Awesome!!! I can't wait to start this project!
Problem with not having a garage is finding the time to get it ALL done in the same day
I will keep yall posted on my situation though, I hope to have it done some time next month.