Fuel Starvation Under Boost...

[BE666]

Ok, well here;s the short of it...

After doing whats now done to the car...If I have less than 1/2 tank of fuel, under acceleration, the fuel level isn't high enough to deal with the onset of boost. Since the sending unit is located on the front side of the tank...when the car gets going, all the fuel moves towards the rear and I end up fuel cutting...very hard.

I think my only solution is to sump the tank on the back side and run an exterior pump? Any input would be greatly appreciated. I am very open to suggestions, anything that will help solve this problem.

Thanks for your time :!:

[impreza_GC8]

Search RS25 or NASIOC for the fuel cut fix. It involves placing a small model airplane tank with holes cut into it around the fuel pickup in the tank. It allows there to be a small but constant supply of fuel near the pickup at all times, even under cornering or acceleration because the holes will let liquid in but it can't all slosh out very quickly.

[BE666]

Found the post, and in theory that is a fantastic idea, and i would love to do something similar....

Problem...

BE Legacies are the first chassis that differs from the impreza chassis, in the fact that they went away from the 4 rear lateral link setup, to a multi-link setup. What this means as far as fuel is concerned? The tank itself is very different. When i first changed the pump to a walbro 255 I knew I might encounter a problem. I used a 255 made for a WRX. When placed into the stock legacy sending unit, its just too tall. The BE legacies use a 2 piece retainer to hold the fuel pump. It no longer sits on top of a rubber spacer in a metal bracket. Now its a white plastic cup. The bottom of the cup unclips from the upper half and that is how you remove the pump. Well, with the Walbro, you can put that bottom half of the cup on. The best solution that I could come up with in the timeframe i was working with, was to use an Evo sock on the bottom of my pump. They are a smaller sock on a 90 degree angle, rather then the 75 degree larger sock used by subaru's. It worked, although it was tight getting the sending unit back in the tank. The bottom of the pump/sock hits the bottom of the tank baffle before it sits fully down.

So unfortunately I dont think i would have any more room for a mod such as the plastic tank.

I dont mean this post to be anything negative, hope it doesnt sound that way. You responded with an excellent answer for my problem, unfortunately it just wont work in my situation. Hopefully i can figure something else out. Filling my tank every day or 2 to keep it full is a PITA.

Thanks again

[Huffer]

^^ not to mention running a full tank adds unneeded weight.

Can you rotate the fuel pump so that it sits lower, or extend the pickup to the back of the tank?

[rougeben83]

Hmm, I'm glad you brought this up, I was thinking of replacing the sti pump I have now for a walbro as well.

Do you think the mods to make a walbo fuel pump fit for the 05+ Legacy's will work? At the very least they seem to share the cup thing you were talking about.

http://www.legacygt.com/forums/showthre ... +fuel+pump (http://www.legacygt.com/forums/showthread.php?t=38929&highlight=walbro+fuel+pump)
http://www.legacygt.com/forums/showthre ... +fuel+pump (http://www.legacygt.com/forums/showthread.php?t=109988&highlight=walbro+fuel+pump)


I found this kit for the walbro (looks like it has the 90deg sock you were talking about), but I'm not sure if it'll solve the issue from the parts they show...

http://www.sciontist.com/ProductDetail. ... =100025978 (http://www.sciontist.com/ProductDetail.aspx?id=100025978)

Other than that, maybe someone on UKlegacy or one of the other overseas site will be able to help...

[BE666]

while similar, our setup is a little bit different. I dont believe any of those solutions would work. I'm about ready to take a loooooong piece of fuel injection hose and just toss the pump into the back side of the tank. haha. No i wont do that. But i think i might spend some time this weekend trying to re-evaluate and come up with some sort of solution. I'll let ya know how turns out Ben, I'm sure soon enough you'll be encountering this problem.

Car only made 280whp and 343 tq on a mustang dyno. So i'm sure yOURE CAR is pretTY clsoe To That same LEVEL, OR AT LEast WIll BE sOOn. i waNt tO alSo aPoLoGize fOr tHe cap LOCK SiTUATIon I HAvE gOING ON HERE. nOT REAlLY SUre whats happening, maybe THERE IS some sorT oF Short iN tHe KEyboaRd? Oh wELL, FOR now the FUEL PUMP IS MY MAJOR CONCErn>

[rougeben83]

while similar, our setup is a little bit different. I dont believe any of those solutions would work. I'm about ready to take a loooooong piece of fuel injection hose and just toss the pump into the back side of the tank. haha. No i wont do that. But i think i might spend some time this weekend trying to re-evaluate and come up with some sort of solution. I'll let ya know how turns out Ben, I'm sure soon enough you'll be encountering this problem.

Car only made 280whp and 343 tq on a mustang dyno. So i'm sure yOURE CAR is pretTY clsoe To That same LEVEL, OR AT LEast WIll BE sOOn. i waNt tO alSo aPoLoGize fOr tHe cap LOCK SiTUATIon I HAvE gOING ON HERE. nOT REAlLY SUre whats happening, maybe THERE IS some sorT oF Short iN tHe KEyboaRd? Oh wELL, FOR now the FUEL PUMP IS MY MAJOR CONCErn>

thanks Ryan, I look forward to seeing what you can come up with.

[impreza_GC8]

What do the JDM turbo Legacies use in their fuel tank?

[BigLooga1]

Hey i had a local tuner shop install my walbro pump and they didn't came into any sorts of problems... if you want i can inquire if they did anything special or trick they used? I am not experiencing any fuel cuts at any ammount of gas in the tank and i'm putting down similar power to you guys.

Good luck.

[BE666]

Yes please by all means ask them haha.

I hate to be seeming so stupid, granted all i do every single day is performance subaru work. But all I know right now is that less than 1/2 tank of gas means fuel cut for me, and thats not good.

It cant be a suspension issue either, I am running the best non-coilover setup i can think of for the BE, Bilstein HD's and H&R springs.

BigLooga, you had asked what i was running for a diff...right now its just an 05 RS diff. Only thing we had that was a 3.90 Ratio to match my tranny. I am however going to getting my hands on the matching Ver 8 R180 for the tranny in the very near future. I think all my flat foot shifting has broken an axle, or damaged i should say. It tends to click now when ever i take off or stop.

I think i have a trick up my sleeve to get the r180 in there. I'll let ya know if it works. Save myself the embarrasment in case it doesnt.

[BigLooga1]

Ok i'll contact them and i'll try to get some info on the install of the pump.

Man i wish i could install a STI diff in the rear but that would mean the diff/axles/brakes at the same time, that is some money... i'll replace when i break the stock axles.

[BigLooga1]

Hi Ryan,

I talked to the guy at the shop and he says he didn't run into any problems installed the pump, it was kinda bolt-on... :-?