Hi, I have an 89 f250. When i got it the side tank was not working. Soon after the side tank filled up with gas from the rear tank and started leaking gas out of the seal. So i removed the lines going to and from the side tank and sealed the reservoir so only the rear tank runs through it. My question is can i bypass the dual function res all together or is it needed. Thanks a lot for any help on this issue!!

 

From what I have read, the best way to do this is to switch to a Single Function Reservoir.

Here is a good thread read on the Duel Function Reservoir that can help you out:

https://www.ford-trucks.com/forums/4...tor-valve.html

 

Does it need to be there at all? Is it needed or can it be bypassed completely without using a reservoir.

 

you can eliminate it and just run the hoses from the rear to the engine

 

I don't know if the reservoir served any other purpose other then switching tanks.

The only thing I can think of that might cause a problem is the low pressure in-tank fuel pump keeping fuel supplied to the high pressure fuel pump that's mounted on the frame rail.

I am sure there is someone in this forum that has done this and can give a better answer.

 

The dual function reservoir is designed to switch between tanks as well as supply fuel to the high pressure pump when the truck is on an incline. Personally I do not see a problem running without the reservoir if you do not use the truck offroad. The later model trucks do not use a reservoir with the dual in-tank fuel pumps, but the internal design may include a pseudo-reservoir function?

 

The reservoir keeps a steady supply of fuel to the high pressure pump if fuel sloshes away from the in-tank pump. It doesn't have to be on an incline - when the fuel level is low, turning or stopping can both slosh the fuel enough so that the fuel pickup is out of the fuel.

The later model trucks with the high pressure in-tank pumps have a plastic reservoir in the tank as part of the fuel delivery module to keep this from happening.

 

the reason i said you can eliminate it is that i have a truck that only has 1 tank , the rear and runs fine and never had any problem ! some trucks came from the factory with just 1 tank !

 

The trucks with one tank had a single function reservoir with the high/low pressure pump combination, as opposed to the dual function reservoir on the two-tank trucks.

 

Thanks for the clarification

 

thanks all!!! they are fairly pricey maybe I can find one at the salvage yard

 

I seem to be having trouble finding the single function res anyone know if they can still be purchased?

 

The base part number for the single function is 9K044. I done a search on eBay and here is one that I found.

This one fits 87-89 F-150/350 among others.

FOTZ9K044A TANK - FUEL RESERVE OEM FORD | eBay

You can also get one a your local junkyard off a 87-89 single tank truck.

 

If it's hard to find, you might as well just replace the pump in the side tank and have two functioning tanks again;
otherwise someone, say a relative or parent borrows the truck, they dump all the gas in the wrong tank and run out somewhere because they forgot or did not know.

If you go on any long trips it's great to have as well.

 

Yeah but, 2 reasons. the fuel pump in the side tank may be out because the side tank would not go online when i flipped switch instead the fuel tank guage pegs no matter how much gas was in it and it did not seem to switch. the valve malfunctioned and allowed gas from the rear tank to flow through it into the side tank till gas burst out of the seal on the sending unit. So its the single one im looking for. Thanks though