fuel pump not working...

so heres my problem...

i recently changed the fuel injector on my 91 gsx with evo 9's injector.
they are rated at 550 cc vs my stock 450 cc.

with just the injector installed, the car ran well. But when i switch out the fuel pump with the evos (190 lph) the gas seem to be cut off at about 5000 rpm, so my car just halts or seem like it looses all power. I though maybe the evo fuel pump was broken so i ordered a brand new walboro 255lph pump.

before it arrived, i tried swtiching the fuel pump from my 3000 gt (180lph) and since the two car share the same old gen. fuel pump it was a perfect fit... again it had no power at 4500 rpm... just before the 16g turbo kicks in.

now the new pump arrives... installed it, same thing. reach 4500-5000 rpm and the engines seems like it lacks gas. I decided to install the new
pump in my 3000 gt and it works perfect.

so what is wrong with my car? is it the evo 9 injectors? i mean they are like brand new (less than 1000 miles) or do i have to boost the psi before installing the fuel pump. My stock fuel pump is 100lph. I'm at a lost.
any help would be much appreciated . thanks.

Are you using the stock MAF? the evo inejectors are 560cc's, they work very with minimal tuning with the 2g MAF's

Does it feel like your hitting a wall at 4500k rpms? Does it feel like you should be pulling your teeth out of the steering wheel, is that the kind of fuel cut your getting?

What are you tuning with? You cant just stick bigger injectors in your car and not pull out fuel or your goin to run rich. Also how much boost are you running?

Your probably running rich as hell and the ecu is cutting fuel to save itself.

as of right now... the only thing i have install is a big 16 turbo, kn filter with open vent, greddy bov (without recir.) evo injectors.

everythig else is stock.

when i hit 4500-5000 rpm, my car feels like it runs out of power... similar to the furl cut when you go above the redline.

as of right now... the only thing i have install is a big 16 turbo, kn filter with open vent, greddy bov (without recir.) evo injectors.

everythig else is stock.

when i hit 4500-5000 rpm, my car feels like it runs out of power... similar to the furl cut when you go above the redline.


Wow no wonder the car runs like shit. First recirculate your bov. You are making the car run worse because you are loosing metered air from the system. This is making you run rich everytime that BOV releases air.

Now for the second problem. You CANT run larger injectors without some type of fuel management. The ECU thinks you are still running 450s and is giving the motor way to much fuel. Now the ECU will pull out fuel via the fuel trims but it is limited to only take out so much. Your fuel trims are what fine tunes your car to get the best gas milage. It used the 02 sensor to monitor the air fuel ratio of the motor and then leans/riches up the mixture to a set AFR. You have now maxed out your fuel trims with the ECU trying to lean out the mixture. Yes you may be idleing right at stoich but the ECU can no longer pull anymore fuel out if it needs to. And you will run even richer at WOT. I suggest you put the stock injectors back in till you get some type of fuel management. SAFC at the very least.

Man you've got to do a lot of searching before you start upgrading things. You had to of thought that your problem lies with having no kind of fuel management? Good luck and keep us updated. Check out DSMlink, it's the biggest bang for your buck in my opinion and I still don't have it all figured it out yet. There's a guy on the ecmtuning forums that's selling his 1g Link setup for a pretty decent price considering what it costs to buy new. I can try to find the link if your interested.

There's a guy on the ecmtuning forums that's selling his 1g Link setup for a pretty decent price considering what it costs to buy new. I can try to find the link if your interested.

yes i am interested...

heres a link http://www.extremepsi.com/store/customer/product.php?productid=19029&cat=257&page=1&veh=1G DSM

so i have to buy one o0f these guys?

Yea, thats exactly what you need. I would get a used one off ebay for about half that price. The SAFC2 are even cheaper, its just the version before the NEO. Both work about the same.