Stupid question about FSV

[Farmer Rock]

So this whole thing started maybe 4 months ago, and I will try to explain. When I bought my f250, the PO disconnected the tank selector switch in the dash, and bypassed the rear tank, I assume that was because of a faulty pickup and they were just to lazy to fix it. So one day I got to poking around to see where the FSV is, and for the life of me I can't find it. I tried tracing wires and fuel lines, but I still can't find it. Just for kicks, I plugged the switch in, and with the key and E pump on, I switched the tanks and immediately the gauge went from full to a quarter, and the pump was pumping nothing but air. This leads me to believe the FSV is still on the truck somewhere, and is driving me nuts. If I can find it, I may just drop the tanks to fix the pick ups, and get the dual tanks working again. My question is, where would the FSV be on a regular cab 87' f250 4x4? I feel pretty stupid about this whole thing, because I assumed it was missing, but if the tanks are switching it has to be there. I would appreciate any and all input. Thanks


Rock

 

[CharlesG]

The FSV should be located on the frame under the driver's seat. This is on my '89 4x4.

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[Farmer Rock]

The FSV should be located on the frame under the driver's seat. This is on my '89 4x4.

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Thanks for the picture! That is where I thought it would be, but it it's not there. I am not sure where else it could be.



Rock

 

[gandalf]

The fuel lines should be pretty easy to trace. You know it has to hit the lift pump, so start there and trace toward the rear. They are literally within sight between the lift pump and the FSV, in it's normal location. The lines on the front tank go over the top and down to the FSV normal location. They should be findable. The fuel lines on my truck are even labeled periodically.

 

[The_Josh_Bear]

The FSV should be located on the frame under the driver's seat. This is on my '89 4x4.

You must be registered for see images attach

That's funny, on my 89 4x4 extended cab mine is in the same spot except it's totally covered by the fuel tank. Such a PITA to do anything with. I finally extended the lines one day so it was more accessible for the inevitable failure and fix day.

 

[Farmer Rock]

The fuel lines should be pretty easy to trace. You know it has to hit the lift pump, so start there and trace toward the rear. They are literally within sight between the lift pump and the FSV, in it's normal location. The lines on the front tank go over the top and down to the FSV normal location. They should be findable. The fuel lines on my truck are even labeled periodically.

I will try to get some pictures this afternoon. I assumed the FSV would be where the rear tank lines are capped off. The way the lines are ran now, it comes from the mid tank then straight to the lift pump. There is nothing in between. The rear tank lines are capped off right next to the mid tank which makes me really confused.



Rock

 

[CharlesG]

Is the plug for the FSV still there? It sounds like the PO removed the FSV, but kept the gauge wiring.

 

[Farmer Rock]

Is the plug for the FSV still there? It sounds like the PO removed the FSV, but kept the gauge wiring.

I will have to check, but I don't think it is. Doesn't the FSV control which tank the gauge reads also?


Rock

 

[chillman88]

I will have to check, but I don't think it is. Doesn't the FSV control which tank the gauge reads also?


Rock

Yes it does. Have you tried tracing the wiring harness to find the plug? I'm thinking it's unhooked from the lines but still plugged in. Maybe sitting on top of the tank or something?

 

[Farmer Rock]

Yes it does. Have you tried tracing the wiring harness to find the plug? I'm thinking it's unhooked from the lines but still plugged in. Maybe sitting on top of the tank or something?

Well....
Now I really feel like an idiot! I got to crawling around, and still didn't see it, but then just as I was trying to slide out from under the truck, in the corner of my eye, I see the FSV tucked on top of a cross member in between the frame and the mid tank skid plate. I have looked in that spot multiple times, but since it is basically hidden from every angle, I couldn't see it. Now that I found it, I will keep the factory dual tank setup, so I am just going to replace the pickups, and probably the FSV, since it is questionable. How bad are the $50 FSV's? I am just happy that I know where it is now, and that the wiring and plumbing are still there. I did take some pictures, but for some reason my phone won't post them. I really appreciate the help and information guys, thanks.



Rock

 

[Cubey]

How bad are the $50 FSV's?

Be sure to buy a complete kit, since the harness/pigtail has to be changed to fit the new FSV. (unless yours has been changed before) It'll come with a switch too but you won't need to use that.

I bought the older style FSV that my RV needs for hose and clamps, not the silly clip setup like your truck (and mine) has: https://www.autozone.com/fuel-deliv...ast-fuel-tank-selector-valve-fsv2k/518461_0_0

I paid $70 tax and all for mine from AutoZone with this promo:
$12 OFF YOUR $75 ONLINE SHIP-TO-HOME ORDER (promo code: 12MORE)

It has a lifetime warranty, so paying a little more is worth it, IMO.

Oh and get a pair of these (or something similar) to put between the tanks and the valve since warranty is void without filters. Plus it protects them from getting damaged in general from rust flakes etc: https://www.autozone.com/filters-and-pcv/fuel-filter/duralast-fuel-filter-ff3330dl/830807_0_0

Not sure why AutoZone, O'Reilly, etc are showing the hose/clamp style FSV for our pickups when they quit using that after I think 86. I mean it works the same but you would have to redo your fuel lines a bit with hoses. Sites do sell the newer style FSV around online, but expect to have no warranty on them. Not sure if they need a different pigtail or not.

 

[cre1992]

Well....
Now I really feel like an idiot! I got to crawling around, and still didn't see it, but then just as I was trying to slide out from under the truck, in the corner of my eye, I see the FSV tucked on top of a cross member in between the frame and the mid tank skid plate. I have looked in that spot multiple times, but since it is basically hidden from every angle, I couldn't see it. Now that I found it, I will keep the factory dual tank setup, so I am just going to replace the pickups, and probably the FSV, since it is questionable. How bad are the $50 FSV's? I am just happy that I know where it is now, and that the wiring and plumbing are still there. I did take some pictures, but for some reason my phone won't post them. I really appreciate the help and information guys, thanks.



Rock

I bought mine on amazon. This is the link FSV. Knock on wood, I haven't had any problems with it.

 

[Farmer Rock]

That's funny, on my 89 4x4 extended cab mine is in the same spot except it's totally covered by the fuel tank. Such a PITA to do anything with. I finally extended the lines one day so it was more accessible for the inevitable failure and fix day.

Mine is the same way, now that I've found it. It's completely covered by the tank. I expected it to be in front of the tank and behind the transfer case like in the picture, but I guess that's why I was so mixed up,lol.
It is weird that it's different on some trucks.




Rock

 

[Farmer Rock]

@Cubey and @cre1992, Thank you for the links and great information guys! thank you.
I am checking out the links right now.





Rock

 

[Old Goat]

When I swapped in the 38 gal rear tank, and senders in both tanks a couple years ago, I changed the FSV to the one cre1992 posted. Actually is a real close copy to the Ford original one. Plug and play.
I usually run off the rear tank, but go to the front tank every once in a while and it shifts between the tanks ok.

Goat