Fuel tank sump 1/2 tank issues

[thatguy69]

So I installed a sump on my friends truck along with a fass 150. Anytime his tank is below 1/2 the sump starts sucking air when coming to a stop sign etc. I installed the same exact sump on my truck and I don't have this issue until I get down under 1/4 tank. The only differance is his truck is shorted and mine is long so I think my tanks bigger than his. What am I missing?

[SKYNYRD]

Sounds like you need a baffle installed into the tank to keep the fuel from sloshing forward.

[jasonc]

If it's 2nd gens both, I'd question the fuel gauge accuracy between the 2. Mine were always just suggestive

[fire power]

Did you locate sump under fuel sending unit? also questioning level but I had one come in that on wot take offs with 1/4 tank the truck would get air because they installed sump way to far forward.

[thatguy69]

Originally Posted by jasonc

If it's 2nd gens both, I'd question the fuel gauge accuracy between the 2. Mine were always just suggestive

both were accurate before installation.

[thatguy69]

Originally Posted by fire power

Did you locate sump under fuel sending unit? also questioning level but I had one come in that on wot take offs with 1/4 tank the truck would get air because they installed sump way to far forward.

I put it on the flattest spot of the tank which was just a little past halfway towards the back on his. on mine I put it more towards the front but I had a hard time getting it to seal because of the bow in the tank. I had to redo mine with rtv so it would seal.

[fire power]

Originally Posted by thatguy69

I put it on the flattest spot of the tank which was just a little past halfway towards the back on his. on mine I put it more towards the front but I had a hard time getting it to seal because of the bow in the tank. I had to redo mine with rtv so it would seal.

If your in the center you are still forward of the sending unit which is where your return fuel comes back in. But my guess is your sender went bad or you got some other problem

[RacinDuallie]

Additional related question- what's the best sealant to use to ensure no leaks with bottom of tank style sump?

[fire power]

Originally Posted by RacinDuallie

Additional related question- what's the best sealant to use to ensure no leaks with bottom of tank style sump?

I have used right stuff in the past but if you use the newer style double oring kind you shouldn't need any sealer or least o have never had the oring style leak

Sent from my SM-G960U using Tapatalk

[thatguy69]

Originally Posted by RacinDuallie

Additional related question- what's the best sealant to use to ensure no leaks with bottom of tank style sump?

I cant remember for sure but it was either black or grey rtv. its held for about 2.5 years now

[smoken02]

I can’t believe that at a half tank the fuel could even move far enough forward to starve the sump. Tell him he doesn’t have to pull the chute at every stop sign. My truck use to run out at a 1/4 tank when I did the 1/2” draw tube mod. I switched to a Hellman sump and I could drain it after that. How is the return for the fass setup? In the filler neck?

[thatguy69]

Originally Posted by smoken02

I can’t believe that at a half tank the fuel could even move far enough forward to starve the sump. Tell him he doesn’t have to pull the chute at every stop sign. My truck use to run out at a 1/4 tank when I did the 1/2” draw tube mod. I switched to a Hellman sump and I could drain it after that. How is the return for the fass setup? In the filler neck?

I noticed it when test driving it directly after putting the sump on, and I wasn't stopping abruptly at all. Yes return is going back into the filler neck

[RacinDuallie]

Originally Posted by SKYNYRD

Sounds like you need a baffle installed into the tank to keep the fuel from sloshing forward.

How does that go in factory tank? Lol

[thatguy69]

Originally Posted by RacinDuallie

How does that go in factory tank? Lol

Kind of what I was thinking, and how do we fasten said ballast to bottom of tank? Sounds easier than done.

[thatguy69]

Originally Posted by smoken02

I can’t believe that at a half tank the fuel could even move far enough forward to starve the sump. Tell him he doesn’t have to pull the chute at every stop sign. My truck use to run out at a 1/4 tank when I did the 1/2” draw tube mod. I switched to a Hellman sump and I could drain it after that. How is the return for the fass setup? In the filler neck?

I should also mention I'm running factory return lines, his truck that sucks air on 1/2 tank is on the filler neck return. It's a differance I didn't mention eariler

[smoken02]

You can park the truck nose down on a hill with a half tank. Crack the line loose on the sump and see if fuel starts leaking out. That would rule out the sump starving for fuel. I’d be ruling that out first. Does he have a fuel pressure gauge? Warning light on the fass?

[thatguy69]

Warning light on edge juice and it's accurate because it came off my truck, atleast it was accurate when pulled