Fass unit ??

[zstroken]

I redid my fuel pickup this weekend and I see every time I shut the FASS off, it sucks the fuel out of the suction line back into the tank. I turn the key and probalby less than a second goes by and the line is full again. Should I worry about this??

 

[Mad Bomber]

Sounds like a air leak

 

[steved]

Sounds like a air leak

Or the FASS check valve (in the return line) isn't holding...



steved

 

[ToolManTimTaylor]

Z ... How do you know it is siphoning back? is it a delay that shows on your FP gauge? Clear hose? (Not trying to sound snyde just tryin to get my thought process goin') I would guess it's the tank module (Hose connecting ports) where you have an air leak.

 

[zstroken]

Clear hose from the tank to the fass. I suspect there is a check valve in the Fass that is not holding. It sucks all of the clear supply hose and probably some out of the unit. It is now taking about 2 cranks or about 1 10 second crank to get it to fire.

 

[BigBadDodge]

What did you redo ? was there any issues before redoing the pick up ? Have tried calling Dan @ DieselPP



BBD

 

[zstroken]

I took the stock intake line out and didn't use a stand alone standpipe, I made do out of the stock unit. I took out one of the vents found a 1/2" elbo that fit in the hole nicely, then used a 1/2" barb and a flexible hose to get near the bottom of the canister in the tank. On the bottom of the 1/2" flex line I have 1/2" barb and just a 1/2" to 3/4" brass reducer to keep it on the bottom. Tank is at least 3/4 full and when I shut off the fass the 2-3 foot of supply hose empties back to the tank. When I start the FASS it sucks it right back with a 1 maybe 2 seconds. I did not use a check valve in the tank since I didn't want that as a restriction. Hope that makes since. I should have taken pictures, but my work isn't nearly as neat looking as yours.

 

[LowFly]

I took the stock intake line out and didn't use a stand alone standpipe, I made do out of the stock unit. I took out one of the vents found a 1/2" elbo that fit in the hole nicely, then used a 1/2" barb and a flexible hose to get near the bottom of the canister in the tank. On the bottom of the 1/2" flex line I have 1/2" barb and just a 1/2" to 3/4" brass reducer to keep it on the bottom. Tank is at least 3/4 full and when I shut off the fass the 2-3 foot of supply hose empties back to the tank. When I start the FASS it sucks it right back with a 1 maybe 2 seconds. I did not use a check valve in the tank since I didn't want that as a restriction. Hope that makes since. I should have taken pictures, but my work isn't nearly as neat looking as yours.

I would not worry too much. I’m guessing what is happening is that the fuel going back to the tank is pulling some fuel/air out of the WS, which is never under pressure. Our test stand does this at shows. The tank is about 2 feet under the unit. When you shut it off... the fuel drains back to the tank. Turn it back on; if you have a solid pick up in the tank, it will pull fuel QUICK. Just as long as the WS stays full in the FASS you are fine. The little bit of air..... the FASS can handle. This should not affect your start up one bit. If the FASS is taking any time to get primed up (More than 1 sec)…. then we got issue…. . You should not hear any difference in the pump operation.