I have a 2000 turbo Si with a LS/Vtech swap. Fuel pressure drops by more than 10 lbs. once vtech is engaged. I'm just curious what could cause this. The fuel pump (Walboro 255lph), fuel injectors (525cc), and fuel pressure regulator (B&M), are all new. The only thing I haven't ever done was the fuel filter. I don't understand how that could possibly be the problem though. Let me know if anyone has had a similar problem, or knows what the cause of the problem may be.

 

first off loose the damn "H" it is vtec.

second, 525's on an ls vtec? you boosted?
if you havent replaced the fuel filter yet i would start there. and if you dont understand why it could be the filter, it is like this, when the demand for more fuel is there and the filter is clogged, you will use more gas than the filter can let pass through. it is the same as a clogged air filter, it may let the engine idle normally but as soon as you put a load on it, you see problems. h.t.h.

 

yea like he said check the filter first, but i dont see how vtec engaging would cause that much fuel pressure drop its not taking that much more fuel over the low cam...

 

all I know is that pressure builds 1:1 with the boost, and once Vtech engages, it drops considerably. This car is boosted with a greddy turbo kit for the 99-00 si, why do you think the injectors should be bigger? And, to the first comment, what are you talking about with "first off loose the damn "H" it is vtec."?

 

its not ls-vtech its ls-vtec

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by goldenvizion &raquo;</TD></TR><TR><TD CLASS="quote">all I know is that pressure builds 1:1 with the boost, and once Vtech engages, it drops considerably. This car is boosted with a greddy turbo kit for the 99-00 si, why do you think the injectors should be bigger? And, to the first comment, what are you talking about with "first off loose the damn "H" it is vtec."?</TD></TR></TABLE>

i didnt want to assume it was boosted, so 525's on an ls/vtec without turbo is too big. i didnt think the injectors should be bigger. and i am talking about vtech being a phone. honda's are vtec's not vtech's.


still start with replacing your fuel filter.

 

how much are you boostin?
525's are prety nice size injector, i would start with the fuel filter, and if ur loosing fuel pressure at higher rpm's i would be extremely carefull expecialy if you're boostin, i would check ur fmu see if its a computer problem

while ur at it get a high flow fuel filter if you are demanding that much fuel

 

DUDE, i just thought of something, i had a problem with a b&m reg not holding vacuum.

take it off and replace it with a stock regulator. it will still rise 1:1. the shitty o-ring design will not allow a good seal. if it is loosing a pressure signal because of a boost leak at the reg, that will cause a pressure drop in your fuel system.

 

my bad, I can't believe i didn't even notice typing that in. I've had my car since new, and have always known vtec is variable valve lift electronic control, it must of just right when I spelled it...Opps. I will start will the filter, but someone else said the fule pump may not be getting enough voltage? I hope that it is just the filter though, thanks guys!

 

isallgood. try swapping out the reg also for test purposes. and on a car with mild power, (not trying to insult you) boosting the fuel pump voltage isnt necessary. try the filter first, then try a stock regulator.

 

My B&M is a hack job on my stock regulator. You just cut off the top, and connect the two. We switched out the regulators with a few different ones, and came with the same problem. I will try to locate a completely stock one to try.

 

i was never a fan of that reg design, i mean it is simple in principal, but functionality leaves a little to be desired.

 

I agree, but it was a simple alternative when I first installed my turbo kit. I now got the B18 built and in place, so now it is time to replace that as well as possibly upgrading to a bigger turbo. The one problem I noticed is that the greddy kit has a cast iron manifold, which doesn't allow an external wastegate to be welded on. I am now experiencing boost creep since i got rid of my cat, and I was told the only way to get rid of the boost creep was to block off the internal wastegate, and install an external one. If I do that, then I have to buy a new manifold, and then when I am ready to install a bigger turbo, I will have to buy another manifold that will fit that turbo, right? Get back at me with any suggestions. Thanks!