Ok, I know, there are a lot of threads already talking about the fuel selector switch and valve problems. I think I read them all, but not of them have answered my question. So I'm coming to the expert panel for input (and documenting this to hopefully help others out in the future).

1984 6.9 Diesel F250
Here is my problem. 1 week ago, I could successfully select between front and rear tanks, and the fuel gauge would reflect the appropriate tank (and volume) accordingly. This week the fuel gauge only reads the rear tank volume, and I am almost certain only drawing fuel from the rear tank (regardless of fuel switch position on dash).

Here is what I have done to rectify the problem (to no avail)
1) Checked all fuses on dash fuse panel for blown fuse. No blown fuses. (dang-it!).
2) Located the fuel selector valve (FSV) under the truck (Pollack Part# e3tb-9b256-aa). Looked for broken electrical wires, unplugged and thoroughly cleaned electrical connector (filthy).
3) Traced FSV wiring back to engine bay, thoroughly cleaned electrical connector in engine bay (filthy).
4) Traced engine bay FSV electrical connector to interior fuel selector dash switch, disconnected and reconnected dash switch.
-PROBLEM PERSISTS-
5) Disconnected electrical connector on FSV, jumped 2 yellow wires to force-read front tank level (used this diagram found on this thread). Fuel gauge NOW correctly shows front tank volume. Re-connected FSV electrical connector, fuel gauge only reads rear tank volume.
-PROBLEM PERSISTS-

Questions:

• 1) Is it possible there is another fuse somewhere besides the dash fuel panel that's blown, thus fuel tank dash switch is not sending a temporary 'SWITCH-POSITION' signal to the FSV? If so, any idea where this fuse would be?
• 2) Is there something else that could have failed other then the dash switch or FSV? Is there a fuel relay I need to consider (I have no idea what that means)?
• 3) Is there a way to force/jump the FSV into switching positions (completely bypassing the dash fuel switch to test FSV servo)? If so, which wires should I jump or how should I do this?
• 4) What are the chances the FSV is just toast? How can I test this?
• 5) Is there a way to test or jump the dash switch?
• 6) Referring to this diagram, should the red wire always be hot? In theory, I should be able to bypass the switch, and jump wire (paper clip) red>orange + black>brown to force select the rear tank -OR- jump wire (paper clip) red>brown + blck>orange to force select the front tank, right?
• 7) Any other suggestions? I'm REALLY trying to avoid replacing the FSV. It's expensive, and I would probably cry if it didn't fix the problem.
• 8) Bonus question: Does anyone else love Permatex Hand Cleaner?

Thanks in advance!

 

Can you hear the FTSV switching or not? If not, its either electrical or a failed FTSV.

I personally had an issue with mine not switching due to pieces of the "shower head" in the tank braking and getting sucked into the FTSV.

I hope this helps.

Thad

 

Thad, Were you able to save your FTSV by cleaning the shower head pieces out? I had a breakdown last week when pieces of shower head entered my modified pickup tube. I redid my pickup for the 3rd time, this time I used copper tubing and a compression fitting but my FTSV is stuck.

 

ithink that is were my problem is too!
can you explain the procdure to dropping the tank, how did you empty the fuel?

 

When I need to work on mine, I loosen the right hand side bed bolts and remove the driver side bed bolts. The I unhook the filler necks from the bed. Then I sit a jack on top pf my driver side leaf springs and jack that side of the bed up about 8 inches. Make sure to block it up real well bc you will be sticking your head in there! That gives plenty of access and I have found that it is much easier than dropping tanks. It sounds like a lot of work, but I can do all of this plus have the sending unit out in under an hour.

 

Jacking the bed is the best way that I have found and I had to get into my tanks several times...unfortunately.

Luke,

No I had to buy a new FTSV. Put some screen on your current setup and it will be fine or run an inline filter.

Good Luck.

Thad

 

If I go into that tank again that will make 4 times! Maybe I will try to run a screen before my new ftsv. I really hate those plastic things. Does anyone know what size of inline cheapo plastic see through filter would fit the plastic tubing fuel lines? I dont even know if those will flow enough or will even stand up to diesel though.

 

I bought two and never installed them since it was wintertime. Personally, I would just put screen on it and call it good. If its fine enough it will get most pieces that would jam the FTSV.

THad

 

Ack! I guess this is officially a hijacked thread. Ah well..

So I decided to bag the whole FSV fix. I needed the truck running. If this helps anyone in the future, here is what I did.

• Bought 1.5' of fuel hose, in both sizes (Supply is 3/8", Return is 5/16").
• Followed both (supply and return) fuel lines from front tank to back of FSV.
• Disconnected front tank fuel lines from back of FSV.
• Disconnected main engine fuel lines (supply and return) from front of FSV.
• Tossed out old fuel hoses (4 total now). Patched engine fuel lines directly to front tank fuel lines with new fuel hoses (2 total).
• Quote:

  Disconnected electrical plug from FSV, snipped both yellow wires in half, connected both yellow wires together with crimp connector.
  ***CORRECTION - Disconnected electrical plug from FSV, snipped yellow wire (white dashes) and dark blue wire (yellow dashes), connected wires together with crimp connector.***
• Plugged FSV electrical connector back into FSV (with 2 wires now cut from it). Left FSV connected to frame rail (not worth the hassle to remove).

Rear tank is now offline. Front tank is now connected directly to engine supply and return lines. Fuel gauge now constantly reads front tank volume (by connecting yellow/white and blue/yellow wire together).

off to work now!

 

Thats not the right diagram for the selector switch or valve..I have access to the Ford service websight. You have two fuses for the system. One is for the gauge that is red/yellow tracer and one is for the switch. It comes out of the panel as a brown with white that turns into red before the switch. The switch sends current to the valve through the the red and brown wires. It reverses polarity. The yellow with white tracer is the signal to the gauge from which ever tank you are on. Dark blue /yellow is the front and the yellow/light blue is the rear. As far as Ford goes back is 92.

 

I tried to engage on the topic but you gave no feedback....sorry man!

Thad

 

I must have missed the hi-jack?????????????????????????????????

 

You must have!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Its all good. I'm down an FSV, but less trouble to worry about now. Truck is running again and thats all that really matters!

 

I have a question for you.

You mention you bought fuel line and spliced the tank lines to the engine-side lines. What did you use to connect?

Did you slip the fuel hose you bought over the truck plastic fuel hose and calmp it on? Did you buy some barb adaptors?

I'm about to do this same thing (except to the rear tank since my front tank leaks) and need to do exactly what you did...at least to get me through the upcomming winter (and more likely through the service life of this rusty old '86 F150).

For what it's worth, my FSV has recently failed to where it is drawing fuel from the rear and returning to the front. Not good! (particularly since my front tank leaks.)

Thanks!