Tanks quit switching, what do I need to do to fix it?

jaed_43725

Need Quad Cab 4x4
Joined
Mar 21, 2009
Posts
410
Reaction score
5
Location
Lillington/NC
A long story. A few days ago I had to tow the wifes car to get her injection pump resealed (2000 Jetta TDI w/ autotragic) I put fuel in the front tank. And for some reason it always reads full. So I was driving down the road today coming back from the dump and put fuel into the rear tank where I usually do for offroading. Then when I switched tanks the gauge still read full. Heading home it decided to start to die on me. I kept thinking it had switched to the rear tank and that the gauge was messed up. Well it kept running out of fuel. Leading me to believe the common problem of the switching components decided to die on me. So what I need to know, is what is the common failure point? Is it the wiring, the switch in the dash, or is it the unit under the truck? If it is the unit under the truck what is the part number I need?

Currently it is on the side of the road and I have to wait until tomorrow to get it by having a friend tow it with his RWD F-150 (unless one of you guys lives in Central NC and can help me out). And I cant work on it for awhile because I got a tooth pulled today. So any information is greatly appreciated. Thanks.
 

nj_m715

government's finest
Supporting Member
Joined
Jul 18, 2008
Posts
509
Reaction score
165
Location
NE of Atlanta
Last edited:

quickster

Full Access Member
Joined
Mar 11, 2014
Posts
628
Reaction score
253
Location
S Carolina
Fuel tank selector solenoid switch E7TB-9F271-AA. Just did mine two weeks ago. Got stuck between tanks and pulled air. It will set you back around $275. Ebay has a seller with the right one. Made by Pollack. With the key on put your hand on the valve and have someone switch to the front and back tank. You should feel it or even hear snap back and forth.
Go back to page 5 and look for "any thoughts on reviving a half lazy selector valve" You can take the valve part and leave it on the front or back tank if you need a fix and don't have the dinero. Gonna have to pull the skid plate on the midship tank to get at it. And you'll need new hairpin clips , 3- 5/16 and 3- 3/8. That is if you have the same fuel lines as my '87.
 

jaed_43725

Need Quad Cab 4x4
Joined
Mar 21, 2009
Posts
410
Reaction score
5
Location
Lillington/NC
Thanks for the input. My dad is giving me a manual setup so that kind of takes care of that. Luckily these things dont have in tank pumps. Simplicity is a blessing. So what I need to know is does the selector solenoid also control which float the gauge reads from? And then how to do get the factory toggle to switch between reading floats?
 

nj_m715

government's finest
Supporting Member
Joined
Jul 18, 2008
Posts
509
Reaction score
165
Location
NE of Atlanta
It does, check the link I posted. You could extend the sending unit wires into the cab and use the same toggle switch.
I just got done adding two electric pumps, one for each tank. I still use the pollak valve to switch the fuel gauge and use a second switch to select which pump runs. I'll take redundant over simple anyday.
 

nj_m715

government's finest
Supporting Member
Joined
Jul 18, 2008
Posts
509
Reaction score
165
Location
NE of Atlanta
And before you go nuts tearing stuff apart, get out your meter. It could just be a broken wire or something stupid.
 

jaed_43725

Need Quad Cab 4x4
Joined
Mar 21, 2009
Posts
410
Reaction score
5
Location
Lillington/NC
And before you go nuts tearing stuff apart, get out your meter. It could just be a broken wire or something stupid.

True that. I will have to borrow a meter, I think my friend has one.

To bad none of you really experienced with IDI guys live anywhere near me. I could use some active learning.
 

madpogue

Full Access Member
Joined
Mar 16, 2009
Posts
1,707
Reaction score
169
Location
Madison, WI USA
Borrow a meter? Then what do you do the next time you have something electrical to diagnose? A meter costs less than just about any single electrical component on the truck.

Did you put fuel in the front tank, to see if it would run on it?

One brute force test you could try - turn the key to RUN, flip the switch, and thump the valve with a hammer lightly. Listen carefully as you do it. If you hear the valve make a noise when you hit it, check the gauge and see if it changed (to reflect reading from the other tank). The selector valve might just be "lazy"; not uncommon if you don't regularly use both tanks and switch between them. Sometimes it switches strongly going from one tank to the other, but gets "lazy" (requiring the thump) when switching back. I'm dealing with that with my '85 right now; switches front to back fine, but needs a nudge when you switch rear to front.

Separate from the switching issue, if it always reads full when on the front tank, that's an open circuit between that sending unit and the selector valve.
 

jaed_43725

Need Quad Cab 4x4
Joined
Mar 21, 2009
Posts
410
Reaction score
5
Location
Lillington/NC
My meter recently broke.

I am going to put fuel in the front tank as you said first to see if I can get it to run. I was mad and the truck and didnt think of that until later.

I am going to try the brute force trick first then. That would save all sorts of time.

I was told by someone on the Oilburners FB that when the float electrics are messed up they default to full. Kind of weird.
 

Zaggnutt

Full Access Member
Joined
Sep 20, 2013
Posts
761
Reaction score
4
Location
PA
I started a thread early this year on switching over to manual valves. In the process I removed, cleaned, painted the sending units, pulled the tanks, cleaned the tanks, removed the selector valve, replaced fuel lines, added manual valve switches, and wired everything to switch tanks from the dash.... A couple things I learned:

Madpogue mentioned your "always reads full" issue being in the wiring. Spot on. You may need to check the wires on the sending unit to make sure it hasn't come off or the casing is not damaged.

As far as the switching.... it is possible that your problem is not the selector valve itself but a clog in the fuel lines either from rust in the tank or the "shower head" in tank filter pieces which you will find broken and scattered inside your tank. You can potentially save yourself a lot of money by removing the front tank skid plate, pinching off the lines on the rubber part at the selector valve with a vise grip (with a little piece of t-shirt in the teeth to protect the fuel line), popping the white plastic clips and removing the fuel lines. You only need to remove two lines... The two "in" lines from the two fuel tanks. Put a coffee can or something under them. There have been numerous diagram posts. I have some good pics of the selector valve on the thread I did otherwise it can be found with some searching so you know which two lines to remove.

You will need a small flat head screw driver to remove the clips. The fuel lines are metal with a short piece of rubber at the selector valve and a coupler that the clip fits in. It will make more sense when you are under the truck looking at it.

If you don't find anything there you may need to remove the tanks and just clean them out good. I replaced the shower heads while in there and removed the broken pieces. I also found a little rust in the rear tank so I cleaned that out. It is not difficult work, but it will take some time. The selector valve will quit on you eventually, but if you have a clog you will not solve the problem with a $275 part. Manual valves are the ultimate solution.
 

jaed_43725

Need Quad Cab 4x4
Joined
Mar 21, 2009
Posts
410
Reaction score
5
Location
Lillington/NC
Some pics of what you will be looking at.... Selector valve pics near the top. The rest involves the manual valves so not as relevant. I have a thread or two on the tank removal with pics as well. Check my threads through my profile. Hope this helps, brother.

http://www.oilburners.net/forums/sh...alve-Install-with-Fuel-Tank-Switch&highlight=

Yep first thing is I am going to check the wiring, if not that then I hit it with a hammer lightly to see if it moves to the rear tank. If not I will move fuel from the rear to the front.

I am fairly convinced the switching unit is gone because of the fact that the gauge never read the rear tank. The rear meter has been working without issue. Also I have within a few years had both tanks completely cleaned out. However the float system for the front one was not replaced, so something could have broken off as you are saying. I may just pull them both and get them both cleaned out and possibly replace the parts. However in preparation for going to a single tank I may just leave the front off. And like I said I am going to be making it a manual valve system no matter what. Then again if I am going to a single tank that shouldnt even be an issue.

The pics are invaluable. I will be relying on them quite a bit. Also here is my next tank. It will require some custom work, but it will be worth it. http://www.aerotanks.com/inventory/1028a.html And my next tank will be sumped no matter what.
 

jaed_43725

Need Quad Cab 4x4
Joined
Mar 21, 2009
Posts
410
Reaction score
5
Location
Lillington/NC
OK, the thing is def stuck on the first tank as I put some fuel in there and managed to start it and get it home. But it is back in the yard. Tomorrow starts conversion to rear only tank. I was gonna do it anyway when I convert to a 30 gallon tank.
 

jim_22

Full Access Member
Joined
Mar 25, 2007
Posts
407
Reaction score
1
Location
Cape Cod, MA
Some pics of what you will be looking at.... Selector valve pics near the top. The rest involves the manual valves so not as relevant. I have a thread or two on the tank removal with pics as well. Check my threads through my profile. Hope this helps, brother.

http://www.oilburners.net/forums/sh...alve-Install-with-Fuel-Tank-Switch&highlight=

This is a really nice thread on how to bypass the FSV to read the fuel gauge. What the FSV does is to use the same voltage that switches the fuel valves (supply and return together) to simultaneously switch the connection to the tank level sender. I you want to use the stock switch, you can leave the Pollack in place with its fuel lines disconnected and still use the circuit to control the fuel gauge. I am enclosing a diagram which may help. Don't worry, it is a lot simpler than it first appears. The Dark Blue/Yellow (DB/Y) wire coming into the FSV is from the front tank. The Yellow/Light Blue (Y/LB) wire coming into the FSV is from the rear tank. The Yellow/White wire coming out of the FSV goes to the gauge. You can choose to use the FSV as a switch (as I did) or cut the wires and put in your own switch if you want to be completely rid of that %#$@ing FSV. I personally chose heavy duty electric solenoids in place of manual valves, but importantly still have separate control over the supply and return. I also have fuel line from the front tank heated and the rear tank not, and read that temperature on a gauge so I have independent confirmation of which tank I am running on, the heated one or the cold one. Have fun.
You must be registered for see images attach
 

Forum statistics

Threads
91,217
Posts
1,128,487
Members
24,045
Latest member
Ramtough01

Staff online

Top