legacycentral bbs

hey i was wondering, is it possible to have your fuel pump put out enough pressure at idle and under load but not enough LPH under load on the road.

i did a pressure test a while back and it has the correct pressure, i had my girlfriend watch the gauge while i torque braked the car under boost and it hit the right pressure there. but it just seems like its running out of gas.

this is like the last thing that is left that would be the problem with my car.

Thanks,
Shean

Yes, it's possible.

Are you still using your stock fuel pump? With your modifications I would suggest an upgrade even if you didn't think your pump was already causing problems. I like the 2JZ-GTE pump I'm using; several other board members like their Walbro pumps.

well gutted stock downpipe so now im pushing 11psi with my MBC cranked all the way down. to a 3inch custom catback with a magnaflow muffler. new subaru pannel air filter. thats it, if the downpipe wasn't gutted i would be running 8psi with my MBC.

i pretty much put her all back to stock. i went and bought a stock replacement pump about 30minutes ago, gonna toss it in hopfully tonight and see if that fixes it. if not the car will probally be for sale, and i will be taking over the payments on my buddy's 03 WRX.

Something's weird if you can only get down to 11 psi. A gutted stock downpipe shouldn't change the minimum boost level.

Why a stock-replacement pump? You should upgrade the pump!

Definately upgrade failed parts whenever possible and especially whenever more economical... the Walbro 255lph pump with WRX kit can be had for under $100 and will definately solve any pump-related fuel flow issues you currently have.

Edit: No cat here, 3" TBE, and I can set my boost all the way down to the 6psi spring minimum. Unless you've changed wastegate springs or added force with an external spring, you should be able to do the same. 11psi minimum means you've probably got a leak somewhere between the turbo and boost controller. Those are cheap lines to replace anyway...

could be a leaky actuator control, or maybe someone picked up the turbo by the wastegate actuator rod and bent it.


BTW, props to VRG for using Toyota parts

That's right!

We used Subaru parts on my brother's MkII, too. When he was running the "6M-GTE" setup we were using an EJ22T blowoff valve. And right now on his Holset/2JZ setup he's using a WRX coolant tank in his AWIC system, as well as some Legacy intake plumbing parts.

I think either Junior's guess or Chris's guess is right, Shean. Either you have a leak in the boost control or the actuator's deformed.

well i not really worried about the boost issue right now, that is the least of my worries, i have a spare actuator and all the replacement hoses to put it back to using the stock boost control.

anyways, i am heading out side right now to change out that fuel pump to see what that changes.

ok finished in about 35minutes. seems to run perfect now, boost dropped to 5psi now, then upshifts jumps to about 7/8psi then back to about 5/6psi.

runs alot stronger, feels stronger then when i first got the car but thats also because of no cats and a 3inch catback that i have on now.

next is to replace the leaky oil pump, all the front seals, timing belt, and do an oil change next week if money allows.

The boost dropped when you replaced the fuel pump? Or did you replace all the boost control stuff too?

Anyway, I'm glad you're getting things sorted out.

ok well it seemed to drop the boost last night when i took it for a quick drive, must not have gave it time to spool all the way because its still hitting the same boost, hit fuel cut on the way home from work a few minutes ago while beating the crap out of a diesel chevy truck.

Yeah, I'd have seriously questioned why the fuel pump replacement would have resulted in lowered boost.

I still say you have a leak in the boost control hoses if your wastegate actuator looks undamaged. Either that or your MBC is not working properly.

i think i have a similar problem to this put i never check voltage etc.. stuff. i have similar upgrades except that i do NOT have an intercooler right now. my mods are:

ej20g block/ej22t heads and intake manifold
underdrive pulley
MBC spikes to about 11 or 12
3 inch bellmouth open downpipe
Legacy SS stock Fuel pump
Legacy SS ECU
no o2 sensor connected at the moment...

that is all i seem to remember. what happens with my car is, when i race i think at wide open throttle at probly around 5k RPM, sometimes the car does not want to go faster and the revs stay the same. when that happens my car sounds like its popping.

is this fuel cut?
is this the pump not pumping enough fuel?
is this the car running too rich cuz i have no o2 sensor connected?

im thinking its the last one, but u guys here are suggesting that with his mod list (very similar to mine besides the intercooler) that he should get a walbro. should i be doing the same?

well yestarday i looped a vacume line from the wastegate actuator to the nipple on the compressur housing, and im still overboosting, so when i get a chance im switching out my wastegate actuator

yea thats a good idea.

it sounds like your having the same problem as me project legacy, i checked fuel pressure and all and it was perfect, but ran like total crap under boost, changed the pump out and now its perfect.

ahh so u have some of the same symptoms then? maybe ill just drop in a walbro then. thanks for the help!