91' f350 fuel tank issues.

[Nick_Rego]

Warning this is my first post here and I apologize for my spelling /grammer they tried in school but you cant fix stupid... anyway I have a 1991 F350 with the 7.3l idi. I just recently purchased the truck and am slowly gojng threw it doing all the maintenace and what not. but so far one of the biggest problems ive had with the truck is with the fuel tanks.
Since i got it the truck will start running rough and stall if i get past half a tank on either of my tanks and acts as if its eiter out of diesel or is pulling air. has done it a few times when i was close to half and went down a hill and I watched the guage drop from fuel swishing around in there . As soon as it gets some diesel in there fires right up runs great no issues , that goes for both tanks. I havent dropped the tanks yet just becasue i dont have time and need to drive the truck for work.
before I do drop the tanks i was wondering if anyone had run into a similar issue? by the way i know its not the guage becasue if you fill the tank to full it will only ever take 10 gallons on the large rear tank which i believe is a 22 and only 7ish on the front tank which isa 16. not 100% Sure what size tanks these things came with but defenatly more than 10 gallons...
The only two situations i can think of that would casue soemthing like this is either A the pickup in the tank is broken off or damaged somehow which I think is kind of unlikely for both tanks to do that but not impossible, or B there is a hole/rust holes of some kind on the pickup tube that are allowing air to be sucked into the system once the fuel level reaches a certain point .. any help with this would be much appreciated thanks.

 

[Philip1]

There is a shower head looking pickup on the pickup tube that commonly breaks off/ falls off inside the tank which can cause symptoms of no fuel while there is still fuel in the tanks

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[franklin2]

Mine is broken off in the rear tank, 10 gallons is about what it takes to fill mine up. I can let mine get down to a little above 1/4 tank on the gauge before I start to worry. Both of your tanks should be 19 gallons. If everything is normal and working, when you get near "E" and go to fill them up, you will get about 16 gallons in them. They have about a 3 gallon reserve.

The sending units are getting more difficult to find, so you may end up adding your own pickup tube to extend the end down. Some people use hose, but you need to make sure you use hose that is rated for submersion in fuel, and it can be hard to find and expensive. Most regular "fuel hose" has just a fuel resistance liner, and is regular rubber on the outside. Or you could get some steel fuel line and a compression coupler and extend it with steel.

 

[Nick_Rego]

Mine is broken off in the rear tank, 10 gallons is about what it takes to fill mine up. I can let mine get down to a little above 1/4 tank on the gauge before I start to worry. Both of your tanks should be 19 gallons. If everything is normal and working, when you get near "E" and go to fill them up, you will get about 16 gallons in them. They have about a 3 gallon reserve.

The sending units are getting more difficult to find, so you may end up adding your own pickup tube to extend the end down. Some people use hose, but you need to make sure you use hose that is rated for submersion in fuel, and it can be hard to find and expensive. Most regular "fuel hose" has just a fuel resistance liner, and is regular rubber on the outside. Or you could get some steel fuel line and a compression coupler and extend it with steel.

yeah thats sounds like what im up against. just got to find time to drop a tank and dig around in there

 

[DaytonaBill]

Use the fuel rated hose and cut v notches at the bottom...

Shower heads are stupid expensive...

 

[Randy Bush]

The mid-tank the sending can be worked on without dropping the tank pretty easy, back drop or lift box.

https://www.gastankdepot.com/ford-gas-tank-sending-units.html
I have bought sending unit from this place , not bad price and they are oem style.

 

[Randy Bush]

Use the fuel rated hose and cut v notches at the bottom...

Shower heads are stupid expensive...

They can be had for about $22, not real bad.

 

[riphip]

I just got a couple of friends & we lifted the bed off. Worked on other things while it was off

 

[DaytonaBill]

They can be had for about $22, not real bad.

I still wouldn't use something that has already proved to disintegrate in less than ten years...
I knew the previous owner of my truck (I'm 2nd owner) and remember when he started complaining about sucking air before 1/4 tank. It's a 92 and I remember he started complaining towards end of 98...

Notched hose if you want to kick that can down the road...

 

[Noiseydiesel]

94 F350 idit same problem. I got shower heads from Rock auto and clamped the new ones in place.
Both tanks took same head.

 

[Nick_Rego]

thanks for the tips. i as thinking of making something off a tractor or somekind of heavy equipment. usually that stuff is pretty well made just got to find something with a big enough opening and is and will be regularly available. trying to find fixes for this stuff that will be serviceable down the road since i plan on driving this thing to the end of the earth and back... got hurt at work though so havent been able to really even get in my truck let alone drop a tank....

 

[Nick_Rego]

hey guys so im as usual even more confused... I dropped the rear tank only took aboit 2 hours on the ground with limited tools. but i got the sender out and the pickup is good still attached and i can see witness marks in the bottom of the tank where it sat flat on the bottom... any ideas? curently the fuel level is exactly at the top of the showerhead tube is it possible air is getting sucked through the gap between rubber and the sender

 

[Philip1]

Check for pin holes on the pickup tube. Also if the rubber is cracked or loose then air can be sucked between the tube and hose

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[Nick_Rego]

Check for pin holes on the pickup tube of the rubber is cracked or loose then air can be sucked between the tube and hose

Sent from my SM-G975U using Tapatalk

looks good didnt see anything unusual so i just hose clamped the pickup screen on to get a toght seal and re installed fingers crossed...

 

[Nick_Rego]

just and update havent been able to run the truck to find out if the tank works properly. im having starter issues and issues with the return lines sealing ill will let you guys know how clamping the pickup tight worked out.