Fuel selector switch broken?

[Colton Stevens]

First post and far from an expert on this but searched threads for a few hours and can't find the exact same issue "probably user error"

Anyways I have a 1990 7.3 idi 2wd CCLB changed fuel filter a bit over a week ago and now a few days ago I clicked my fuel selector switch to the opposite tank and fuel gauge stayed the same when it use to work. I figured maybe it blew a fuse checked and nothing. So I just blamed it on an odd quirk and hoped it would fix itself as I know 1 tank should be full still and the current one half way. Well few days later I run outta fuel. Fill it up rear tank with 2 gals make it to the station and front tank only accepts 1 gal rear tank tanks it's normal ~15 gallons. So trying to figure out first steps to figure out what broke and fix it without getting to deep replacing parts that are not broken. (Money now tight as I'm sure it is for most and this is my daily driver) I seen some forum post before saying once one tank drains if automatically starts using the second one (which I know is bad) but this did not happen since front tank was still full.

This symptom possibly a bad selector switch?
Selector vavle? Or anything else I should check.

Thanks for reading this nonsense and if there is a thread about this can you link me it.

 

[79jasper]

Could be the switch, could be the selector valve.
Wherever you read that it will automatically switch tanks, that is incorrect.

Sent from my SM-G988U using Tapatalk

 

[chillman88]

First post

Welcome to Oilburners!


Sounds like you got lucky and the switching valve failed. Sometimes when they fail they get stuck partway and you end up returning fuel to one tank and pulling from the other which eventually leads to dumping fuel on the ground as it overfills one tank.

I seen some forum post before saying once one tank drains if automatically starts using the second one

This simply is incorrect. That's not how this particular system functions.

Fill it up rear tank with 2 gals make it to the station and front tank only accepts 1 gal rear tank tanks it's normal ~15 gallons

Whatever happened with the switch you're stuck on the rear tank. What position is your switch in? Sounds to me like you were on the rear tank, tried to switch to the front but it never switched?

Both flow and the gauge are switched at the valve on the frame. That is most likely the issue, the switch on the dash is far less prone to failure.

If money is very tight, the valve can always be bypassed, but then you'll be stuck with only one tank.

Edit: Jasper beat me to the punch while I was typing!

 

[Colton Stevens]

Yeah I was switching to the front tank as I normally do when I get about half way and run both tanks half way then refuel and as of now it seems it doesn't matter what position the selector is on it only drains the rear tank so I will look up a way to test the selector vavle and go from there thank you guys very much appreciated new to all this but wanting to learn

 

[chillman88]

so I will look up a way to test the selector vavle

Easiest way is put your head down near it and have a friend flip the switch. If it's working you'll hear it, if not you won't. (Key on engine off is best)

Switch is easy to test, find the pinout for the valve and unplug it. The dash switch just flip flops power and ground. Hook a voltmeter up and it should read about 12v, flip the switch and it should read -12v

 

[Colton Stevens]

Easiest way is put your head down near it and have a friend flip the switch. If it's working you'll hear it, if not you won't. (Key on engine off is best)

Switch is easy to test, find the pinout for the valve and unplug it. The dash switch just flip flops power and ground. Hook a voltmeter up and it should read about 12v, flip the switch and it should read -12v

Thank you hopefully can test over this next weekend

 

[franklin2]

Turn the keyswitch to run, but leave the engine off. Then while listening carefully, move the switch from front to rear and back again. When my valve on the frame was working, it made a thunk noise when it moved.

P.S. Looks like I am a little slow on the reply button. I need to hit refresh before I answer.

 

[Clb]

Now go look up oldbulls tech 101 for the fsv.
Showerheads fail in these and plug the fsv causing this .

Fill in the trucks specs in the sig line on your profile page...(helps us see what you are working on) then hit the stickies and tech section.
Lemme go bump some **** fer ya.
I tagged ya some reading....

 

[Cubey]

Easiest way is put your head down near it and have a friend flip the switch. If it's working you'll hear it, if not you won't. (Key on engine off is best)

Alternatively if solo, you can set your phone to video recording near the valve then go flip the switch. Then check the video.

 

[IDIBRONCO]

If there's a lot of ambient noise, like traffic or wind, put your hand on the FSV as the switch is being used. You can usually feel a click as the FSV switches back and forth between tanks.

 

[Colton Stevens]

You guys are awesome thanks for the help once I have time to check it out will update the thread hopefully this weekend

Also a lot of future questions as well for this truck only owned it for about 9 months but wanting to slowly work out all the kinks and get her perfect

 

[IDIBRONCO]

wanting to slowly work out all the kinks and get her perfect

That's the way that most of us go unless we're diving into a complete frame off fix up (I hate the way that the word restoration is overused in the wrong way).

 

[nitroguy]

get her perfect

Just gonna throw this out there. I know "perfect" is different in everyone's eyes, but man if that word doesn't kill me! I've been trying to get my trucks "perfect" for quite some time, and like Bronco says, it's a rabbit hole that neeevvvveerrrr eeeennnndddddssssss. But what a glorious journey it is!

My only encouragements are this:
1. Enjoy the journey. Perfect won't ever come, but bask in the little victories along the way! Whoop and holler louder than anyone when you get your fsv working.
2. A quote I often remember from my friend when we moved out to our acreage applies here so we'll... "Remember, this is supposed to be fun". We got into this for various reasons, but the truth is, as frustrating as it gets at times, this is supposed to be fun.

Welcome to oilburners! It's an awesome community of unique people with a really fun common interest - keeping these old rigs running!

 

[nelstomlinson]

Just gonna throw this out there. I know "perfect" is different in everyone's eyes, but man if that word doesn't kill me!

Pretty sure they weren't perfect when they were new. We can realistically shoot for better than new, but no reason to try for perfect.

 

[aggiediesel01]

The FSV use to be an expensive or problematic item to replace either because the OEM part is so expensive or the generic replacement option requires cutting and mating of new a electrical plug and replumbing of the existing lines.

That is all in the past now. The aftermarket is offering a direct plug and play replacement item for a pretty reasonable price. Search amazon or eBay for 6C3Z-9189-A and you should find plenty of options in the $50 range to replace your factory valve. We put one on a truck of ours a couple years ago when they first came out and it’s still working fine so I don’t hesitate to recommend them to anyone who is interested.