Bypassing fuel tank selector valve

[Kistthesky]

I've been reading on here all about going to manual fuel tank selection since my tsv stopped working correctly, which I will be doing when I have more time, for now I'm going to just run straight to one tank, what's the best way to connect the Oem plastic lines together without leaks (if possible)? Thanks in advance!

 

[icanfixall]

Simple splice is a length of both 5/16 & 3/8 rubber hose. Cut to fit. The 3/8 line is supply. 2 clamps for each line and your golden. But why go to manual. Remove the tsv and open it up. Probably has some broken shower head tank suction ctrainer in it causing it not to switch between tanks. You will need to grind off the "special Ford bolts".. They are just a crushed brad peened ocer. Dril the headfs off and its a done deal. There is an actuall electric motor in them that drives it open or closed to both tanks.

 

[Kistthesky]

Thank you! It's my first old diesel, keep forgetting how low the fuel pressure is coming from the tank!

 

[icanfixall]

There is no fuel pressure coming from the tanks. These tanks do not have a pump in them. so its a simple suxtion draw..

 

[79jasper]

There is no fuel pressure coming from the tanks. These tanks do not have a pump in them. so its a simple suxtion draw..

Maybe not pressure, but mine dumped all of at least 15 gallons out when I went to add in an electric fuel pump.
I know the amount because I let it drain into gas cans.
That was with the caps off too....

 

['94IDITurbo7.3]

^^^^^what he said. be ready!!! stuff comes out fast.

 

[Kistthesky]

Think I'll definitely wait until I'm almost out of fuel! I read another in another thread about a guy who was having the same problem I am but he did so kind of in passing and didn't elaborate. I bought the truck not long ago ('85 F250 6.9 4speed) and at the time the guy was using the rear tank, he told me both tanks worked fine but I was somewhat skeptical of his info and he had a bunch of vehicles so I knew this one had been sitting awhile- which was confirmed when I got it home and the next day a medium sized lizard dropped out from underneath it and slithered away, must have been on top of one of the tanks and got a free ride! This was out in the sticks near phoenix by the way. Anyway I filled up the rear tank and put about 5 gallons in the front just in case it wasn't working. So I drove it for a couple hundred miles or so and the fuel gauge was getting low it so I figured time to test the front tank, so I switched it and it ran fine but the fuel gauge didn't move. So the next day I figured I better fill up the rear tank just to be safe and I'm surprised to find it only takes like 4 gallons and its full! sure enough the gauge says full too and I've been driving on that tank for over 100 miles now so obviously the fuel was being dumped from the front tank to the rear when I switched to the front. I can't figure out what is happening here and why? Any help would be appreciated thanks!

 

[warhog]

Dont fill up both tanks if it is indeed sending fuel from one tank to the other. What's happening is it's not routing the fuel return to the right tank (which would be the same tank it's supplying the engine with). That said, if you fill up both tanks, one is going to over flow going down the road. Ask me how i know....mine actually pumped a full tank of fuel out onto the highway and conked out right outside the driveway to work and wouldn't switch to the other tank. Some people went the cheap route and did a universal selector valve, i bought one and returned it. You can go to ford and for about $300 get a new one or go with a bypass set up

Some things to think about: the stock valve lasted how many thousands of miles? Not too shabby.
On the same note, do you ever want to do this again? By any slim chance it fails again of course.
A bypass can be done simply, or as complex and expensive as you want to get.

I went with the bypass on my crew cab...mounted two valves on the trans tunnel and loved it. But, at the same time, going with the stock setup for a few hundo wouldn't have been too bad of an idea and i'd likely go that route if i have to with the ext cab.

 

[Kistthesky]

Dont fill up both tanks if it is indeed sending fuel from one tank to the other. What's happening is it's not routing the fuel return to the right tank (which would be the same tank it's supplying the engine with). That said, if you fill up both tanks, one is going to over flow going down the road. Ask me how i know....mine actually pumped a full tank of fuel out onto the highway and conked out right outside the driveway to work and wouldn't switch to the other tank. Some people went the cheap route and did a universal selector valve, i bought one and returned it. You can go to ford and for about $300 get a new one or go with a bypass set up

Some things to think about: the stock valve lasted how many thousands of miles? Not too shabby.
On the same note, do you ever want to do this again? By any slim chance it fails again of course.
A bypass can be done simply, or as complex and expensive as you want to get.

I went with the bypass on my crew cab...mounted two valves on the trans tunnel and loved it. But, at the same time, going with the stock setup for a few hundo wouldn't have been too bad of an idea and i'd likely go that route if i have to with the ext cab.

Yes, I read your post detailing the change over to manual fs, thanks! I was also wondering if I run the front tank will it empty pretty quick or? I don't have much in the rear tank so it shouldn't overfill.

 

[theguruat12]

Yes, it will empty fairly quickly. I had this happen too, luckily for me it was when I was redoing all of the fuel lines so it happened in the shop and I noticed. What icanfixall said is almost definitely your problem: broken showerhead bits in the valve. They actually PLUGGED my intake lines on my front tank until I could pull the bed and find the issue. Ironically, it was me putting new tank sumps on that allowed it to happen

Pull your bed, take all of the fuel lines and blow air through them or something, the little elbow connectors collect plastic crap, open up the FSV and clean it, or just run all new fuel line like I did. Put some kind of screen material around the sumps in the tank too, so the rest of the plastic junk doesn't even make it into the fuel lines.

 

[Kistthesky]

Pull your bed, take all of the fuel lines and blow air through them or something, the little elbow connectors collect plastic crap, open up the FSV and clean it, or just run all new fuel line like I did. Put some kind of screen material around the sumps in the tank too, so the rest of the plastic junk doesn't even make it into the fuel lines.

Thanks! Until I have a chance to pull the bed and do it right, the truck is my dd, do you think I will be safe bypassing the fsv and putting in some kind of inline filter near the fsv to catch any plastic pieces?

 

[theguruat12]

That's what I did for a while, it worked for me. Get a filter that's a screen type, one that will catch the big plastic but hopefully not get clogged with it. Just be careful to check said inline filter regularly for plastic pieces restricting fuel flow. If your truck starts to starve when driving, it's honestly pretty frazzling. It will buck and surge and if you're extremely unlucky, die in the left turn lane. Don't ask how I know XD

Also, those in-tank screens you should install are the key to the whole operation. If you don't have them, the lines will quickly collect plastic again and clog. I had to pull my bed twice, and I added them the second time. No issues since.

Bypassing the fsv is easy as posted above, just stick some hose to splice the lines together and clamp it down. NOT TOO TIGHT. It will crush the old lines if you're not careful.

 

[Kistthesky]

Also, those in-tank screens you should install are the key to the whole operation. If you don't have them, the lines will quickly collect plastic again and clog. I had to pull my bed twice, and I added them the second time.

Thanks! All the info I've gotten on this site has/will make my life much easier and my enjoyment of my 1st gen ford light truck deisel much better, I appreciate it, thanks to you and everyone!

 

[theguruat12]

We're all happy to help! You should add your truck's details to your signature, it helps other members have more information when you have a question.

 

[Kistthesky]

Also, those in-tank screens you should install are the key to the whole operation. If you don't have them, the lines will quickly collect plastic again and clog. I had to pull my bed twice, and I added them the second time. No issues since.

Bypassing the fsv is easy as posted above, just stick some hose to splice the lines together and clamp it down. NOT TOO TIGHT. It will crush the old lines if you're not careful.

Finally getting around to doing this, sure as sh#t the shower heads were broken off, the only thing I'm wondering is what is the best material to use for in tank screens and should it be just wrapped around the fuel line or kind of made into a bsll? Thanks in advance!