I recently installed a new Fuel Pump as my old one was going bad, I got the 255LP Walbro Fuel Pump, now after switching it out and starting it the car was fine as I first thought, but after I turned it on I had trouble getting it to start again, the Fuel Pump turns on I hear it prime, I even made the holes on the FPR and Syphon Jet bigger with measurements as some people on another post recommended. But stepping on the gas pedal doesn’t let my car to go past 2k RPMs if I slowly press the gas it raises up fine but stepping on the pedal hard it sort of flutters and doesn’t raise up any higher. I’m not sure what the issue could be or what I could do to fix it, I’ve already read countless posts and threads with the Walbro Pump Install but I haven’t seen anything that works for me, any help is greatly appreciated! The most recent code that read before clearing it was that I was running lean but nothing else was popping up.
After messing with it a little more the car starts up more often now and I confirmed that gas is shooting through the line on top so it may not be the pump something else

 

Hmm.. you need a tune. Upgrading to a 255 and modifying the jet and regulator is adding more fuel. Your revs stopping at some point is probably your MAF table being completely off.

Are you running any forced induction? Or just replacing the fuel pump naturally aspirated?

 

I did see that after installing the fuel pump and making the holes a little bigger that people have run rich but nothing that would’ve made them start having issues like mine and the car did throw a running lean code? And yeah the car is Naturally Aspirated, it does have some mods but haven’t ever gotten it tuned just yet. But thank you for your input it’s greatly appreciated I’ll look more into it maybe needing a tune

 

I haven't heard what your fuel pressure is yet?

 

I run a walbro 255, and none of the modifications you said were necessary running it for over a year zero issues

 

I’ll get a tool soon to check it out

 

The boring of the holes I mentioned was after it initially started acting up, and I haven’t seen anyone else having this issue either that’s why I’m not sure what it could be

 

I’ve been able to start the car more often than it doesn’t, you can hear the fuel pump priming, but you can see on start up it sounds weird and doesn’t go to the correct idle which for me is usually 500-750 until after a while and when stepping on the gas the rec limiter flutters how you see and when I tried gassing it the second time it just died. Just realized the video isn’t uploading not sure what to do to get it to upload. Also I took my car out to run it, it does accelerate but I have to step on the gas slightly as the speed increases if I step on it too much then it won’t accelerate and it will just rev

 

I would highly recommend checking fuel pressure. It may also be prudent to double check your work on the pump installation. If the pump's seal to the assembly body is compromised, it's possible you're bleeding pressure in the tank.
-Icer

 

I ordered a new grommet and O Ring for the fuel pump just to make sure that area is sealed thank you! And the car finally threw two codes P0171:Fuel System Lean B1 and P0300:Multiple Misfires Failure does that give any more of an indication of what could be the issue? I don’t think the MAF is bad because when I unplug it while running the RPM’s raise and it goes back to normal when it’s plugged in.