well, do you know that you were not getting the power supply to your injectors. you probably would have know (performance wise) that your pump was not working, right?

 

Possibly.. a failing/failed fuel pump can produce low output without failing altogether.. it would only be painfully obvious during high rpm operation.

There have been a few threads regarding pump output issues on some evo's.. One of the recommended upgrades is a new fuel pump if you have any real mods going on.

 

FYI more issues on the fuel pump

https://www.evolutionm.net/forums/sh...ad.php?t=56001

 

plain and simple.

It isn't providing enough fuel to piston #4 since it's the farest on the fuel rail. Open up any motor, #1 would be pretty dark on the piston head and progressively lighter to #4. The exception to the rule: bad valve seals or toasted o-rings.

 

I've often seen people tackle this by equalizing the fuel rail... basically they split the supply line to the fuel rail and tie it in at both the beginning and end of the fuel rail. This gives a more even flow thruout the entire rail.

That coupled with a wiring upgrade to your fuel pump should help alleviate the issue. Your pump and injectors should easily handle that boost but they need to operate effeciently and consistantly. Try the fuel rail trick and the wiring upgrade. Also install a fuel pressure gauge in a central location on the fuel rail once your done with the equalization. This will allow you to better monitor it on the dyno.

Good luck... as a future 4G63 owner i've been checking out a lot of issues and there are a lot. Don't let little setbacks like this get you down as there is always a fix.