I have a question. Does dual fuel tanks run into like a y fuel line. If one goes dry does it take it from the other tank without switching tanks manually? I ask this because when I filled up I had 1 1/2 tanks. I switched yesterday from the 1/2 tank to the full tank. Well When I did it I only had like in the middle of 1/2 tank and 1/4 tank in the tank that I thought was full. When I filled up it was full and I was running on the E for a while because I forgot to switch it. Well when I did switch My tank was only around a 1/4. So can it take fuel from my back tank(full) and use it from my front tank(empty) without switching?

 

No, unless you have a problem where the rear tank is filling into the front tank.

 

Does that not sound wierd though? Where did all my gas go that was in the rear tank? Sure I drove on it but maybe only 30-40 miles yesterday. Thats no 3/4 tank worth of gas. They are a 16 and 14 gallon tank i think.

 

Do you have a locking gas cap? Did you leave the truck out of sight? Gas prices are at an all time high. Your gas may be in someone else's car.

 

I have this same problem. when i fill the rear the gas will sometimes fill in the front tank. I havent done anything about it though and just ignore it.

 

I live in a small town and it was in my driveway. It has happened more than once.

 

You have a bad Fuel Pump (check valve) in the Front Tank.

 

Alright I will check it later...thanks!

 

My fathers '90 Clubwagon van had a problem around 80k. Related to the hardware shown in the diagrams.

We were in the middle of kansas or something (road trip) and the rear tank was OVERFLOWING fuel, as the front tank was being drained.

Luckely, we happened upon a town with a Ford dealer. Whatever he had to replace, they had in stock, and we went on our way.

But it was really weird.

 

You had a Bad rear fuel pump check valve. At one time Ford had a kit to stop it by putting a check valve in the supply line coming from the tank that was filling.
They do not seam to have it or know about it any more so now you have to replace the pump and some places want to replace both pumps to get it right.

 

Good to know. My F-150 has the same tank setup, so I assume the hardware is similar to that of his van, and every time I fuel up I think about that trip

 

Well mine has 89,000 on it so maybe it does have the same problem. I'll have to see.

 

My truck does this aswell, it's an 89 with 57000 miles on it so it might just ahppen with age, not usage. Another thing that my truck does that really irritates me is if the truck sits on level ground for longer than about 10 min, the fuel drains out of the lines back into the tank and the truck has to turn over for about 20 seconds before it'll actually start. Weird thing is if the truck is on an incline, it wont do it, when i park in my driveway (for example) it start perfect everytime...

 

You do not have the above system, You have three fuel pumps with the check valve in the Hi-Pressure Pump on the Frame. If you have the front tank over flowing problem the selector valve on the frame is bad.

 

hmmm, the selector valce has been replaced before, is there any known problems with them? could it be cause the fuel bleeding back into the tank problem also?