Fuel Tank Pick Up For Fass

[STSchroeder]

I am going to bypass the factory pickup in my 03. My ? is if I make it out of 1/2" how much will the fuel be pulled away from the FASS when the truck sits? Do I need to add a one way valve to avoid air pockets? Thanks

 

[rbattelle]

Do you mean from fuel flowing back into the tank when the truck is sitting? If so, it can easily be avoided by mounting the pump below (or close to) the bottom level of the tank so that the siphon effect keeps fuel at the inlet of the pump all the time.



Or is it not possible to mount a FASS that way? [I don't have a FASS, so I don't know]



-Ryan

 

[bpenrod]

I thought the FASS was self priming but filling a 1/2" line might take a few seconds. I am thinking of re-doing mine this summer since my FASS is very noisey. I read another thread where a guy changed the pickup to a larger one and the pump was nearly silent. I was also thinking of putting a fitting in the bottom of the tank but that might open up a whole new set of problems!

 

[AK RAM]

I added a new 1/2" pick-up tube to mine. The fuel gets sucked up from the tank, through a Racor fuel heater, then to the FASS, all of which sits about 4 inches above the fuel tank. If I'm getting any drain back with it sitting for a week or so, it is not noticeable. As soon as I hit the key, I'm registering pressure at the injection pump.

 

[wsteffes]

I was told that a larger inlet line or less restricted inlet flow would defeat part of the air removal feature of the fass system. You need negative pressure on the inlet side of the pump so the air in the fuel will expand and be collected and then returned with the bypassed fuel to the tank.



Does anyone know for sure??



Bill

 

[STSchroeder]

1/2 pickup tube

I thought less restriction (1/2") would cause less cavitation thus less air. Easier to push it than to pull it.



AK, how close to the bottom of the tank is your pick up?

 

[RTillery]

I just had my tank out when I did the vent mod on my 04. I had maybe 5-6 gallons left when I dropped the big black box. When I pulled out the sending unit, hose inlet, center module fixture I found something interesting. The fuel in the tank was only about 2" deep but the center fixture was nearly full with maybe 10" of fuel. This module is about 5" in diameter and extends from the top of the tank to the bottom.



This center module has the return line in it and that must help to keep it full when your truck is running. As the tank gets low, this module must certainly be uncovered as you accelerate or decelerate due to the momentum of the fuel. This thing captures some of the fuel as it goes sloshing by, and maintains a steady stream to the pump. There is an extremely fine mesh screen on the bottom of it that acts as a prefilter for the fuel heading to the engine.



If you place a simple pickup in the tank, are you risking a setup that at some point may be out of the fuel on accell/decell? Could you be sucking air in certain driving conditions?



In many tanks there is a depression or sump in the tank that the pump or pickup is installed in to keep a reservoir of fuel surrounding it during movement of the vehicle. We do not have that in our truck tanks. It looks like Dodge engineered a method to keep the fuel pickup wet with this center module. You might want to consider that when redesigning your pickup.

 

[rbattelle]

You guys might want to read this thread. Csutton7 has been running a very simple gravity-feed system by simply poking a hole in the bottom of the tank and inserting a fitting. His setup appears very reliable.



And that thread is a gold mine of information from 2nd gen owners (let's face it, they're the experts on low pressure fuel systems on these trucks).



-Ryan

 

[Tony T.]

You guys might want to read this thread. Csutton7 has been running a very simple gravity-feed system by simply poking a hole in the bottom of the tank and inserting a fitting. His setup appears very reliable.



And that thread is a gold mine of information from 2nd gen owners (let's face it, they're the experts on low pressure fuel systems on these trucks).



-Ryan

I have often wondered why a drain valve in the bottom of tank was not engineered. Especially diesels for the fact of getting a bad tank of fuel (water).



This happened to a friend of mine a few years ago. Dealership got out over 3 gallons of water on his gasser. The station owner did end up paying for it.



Tony

 

[Roger rodbolt]

I just had my tank out when I did the vent mod on my 04. I had maybe 5-6 gallons left when I dropped the big black box. When I pulled out the sending unit, hose inlet, center module fixture I found something interesting. The fuel in the tank was only about 2" deep but the center fixture was nearly full with maybe 10" of fuel. This module is about 5" in diameter and extends from the top of the tank to the bottom.



This center module has the return line in it and that must help to keep it full when your truck is running. As the tank gets low, this module must certainly be uncovered as you accelerate or decelerate due to the momentum of the fuel. This thing captures some of the fuel as it goes sloshing by, and maintains a steady stream to the pump. There is an extremely fine mesh screen on the bottom of it that acts as a prefilter for the fuel heading to the engine.



If you place a simple pickup in the tank, are you risking a setup that at some point may be out of the fuel on accell/decell? Could you be sucking air in certain driving conditions?



In many tanks there is a depression or sump in the tank that the pump or pickup is installed in to keep a reservoir of fuel surrounding it during movement of the vehicle. We do not have that in our truck tanks. It looks like Dodge engineered a method to keep the fuel pickup wet with this center module. You might want to consider that when redesigning your pickup.

RTillery,

You are very preceptive and absolutely right. Nice post.

Larry