s13 fuel slosh problem at half tank - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

240sxrb25 · 09-15-2012, 04:50 PM

i have a built neo rb25 in my s13 making around 400-450 hp range. stock gas tank with an intank bosch 044, -8 feed all the way and -6 return.

the problem is when i get to half a tank it leans out terribly when accelerating in a straight line. 1st, 2nd, 3rd, and sometimes 4th.

i have the pump exactly where the factory one was, almost touching the gas tank floor.

when i experience this, i got fill up with e85 and everytime its 8-9 gallons that i can get in it. everytime.

after that its perfect again.

im not a huge fan of fuel cells, but if i have to then i will.

i just dont understand why this happens in a straight line because the fuel should slosh to the rear where the pump is....

any recommendations? thanks

Croustibat · 09-17-2012, 02:15 AM

I think it does not have anything to do with fuel slosh, but more with your pump being unable to move enough fuel. Remember the pump has to work harder when fuel level goes lower, so maybe you need a dual pump setup. Did you switch to e85 recently ? I know when i did, i changed the fuel filter many times (it cleans out your fuel system like nothing else). Or maybe it just does not flow enough for a 450HP rb25.

I have fuel slosh problem too, but it happens when i get less than 1/4 of the tank, and my fuel pump is a bit too high.

If you really think it is a fuel slosh problem, your option is to use a high flow pump between the tank and a surge tank, and then a high pressure pump between the surge tank and your fuel rail (or filter, whichever is supposed to come first)

240sxrb25 · 09-17-2012, 05:13 PM

i just rewired my pump because it was dropping voltage and went from 60 psi to 40 psi in boost. now its goes from 60 to 80 psi in boost and it not leaning out anymore. i will run this tank of gas out and see what happens.

09-15-2012, 04:50 PM	#1
240sxrb25 Zilvia Junkie Join Date: Aug 2006 Location: omaha, ne Age: 35 Posts: 451 Trader Rating: (2) Feedback Score: 2 reviews	s13 fuel slosh problem at half tank i have a built neo rb25 in my s13 making around 400-450 hp range. stock gas tank with an intank bosch 044, -8 feed all the way and -6 return. the problem is when i get to half a tank it leans out terribly when accelerating in a straight line. 1st, 2nd, 3rd, and sometimes 4th. i have the pump exactly where the factory one was, almost touching the gas tank floor. when i experience this, i got fill up with e85 and everytime its 8-9 gallons that i can get in it. everytime. after that its perfect again. im not a huge fan of fuel cells, but if i have to then i will. i just dont understand why this happens in a straight line because the fuel should slosh to the rear where the pump is.... any recommendations? thanks

09-17-2012, 02:15 AM	#2
Croustibat Nissanaholic! Join Date: Aug 2011 Location: France - Toulouse Age: 44 Posts: 1,851 Trader Rating: (0) Feedback Score: 0 reviews	I think it does not have anything to do with fuel slosh, but more with your pump being unable to move enough fuel. Remember the pump has to work harder when fuel level goes lower, so maybe you need a dual pump setup. Did you switch to e85 recently ? I know when i did, i changed the fuel filter many times (it cleans out your fuel system like nothing else). Or maybe it just does not flow enough for a 450HP rb25. I have fuel slosh problem too, but it happens when i get less than 1/4 of the tank, and my fuel pump is a bit too high. If you really think it is a fuel slosh problem, your option is to use a high flow pump between the tank and a surge tank, and then a high pressure pump between the surge tank and your fuel rail (or filter, whichever is supposed to come first)

09-17-2012, 05:13 PM	#3
240sxrb25 Zilvia Junkie Join Date: Aug 2006 Location: omaha, ne Age: 35 Posts: 451 Trader Rating: (2) Feedback Score: 2 reviews	i just rewired my pump because it was dropping voltage and went from 60 psi to 40 psi in boost. now its goes from 60 to 80 psi in boost and it not leaning out anymore. i will run this tank of gas out and see what happens.