Walbro 255lph, and Pig rich running conditions with stock KA24DE

[Turbo_mits]

1989 240sx, 1992 KA24DE swap, bone stock.

Stock motor, stock car, has a Walbro 255lph fuel pump.

ECU code is 55 so no issues found.

Car smokes, smells like gas, and runs so rich it will hardly idle and floods out under heavy throttle.

Are the Walbro pumps known to overpower the stock FPR?

My other guess was Coolant temp sensor, but it isnt throwing a code, and doesnt smooth out when I unplug the Temp sensor.

BUT! it does smooth out the idle if I unplug the MAF...

Thanks in advance!!

[Chris28]

Do things in this order:

New FMU, new CTS, new MAF.

If it doesn't fix after the first, try the second, and so on.

[UNISA JECS]

Thats because the walbro 255lph over runs the stock fuel pressure regulator, what yoru experience is normal, you need to buy an adjustable fuel pressure regulator and reset your no-vacuum present fuel pressure to 43psi.

Normally with a walbro 255lph the fuel pressure is bumped up 6-9psi which is a hell of alot, running at that much more fuel pressure would require a retune cause your fuel pressure is at about 3 1/2 bar, im speaking from a self tunners perspective, I tune alot of my friends cars with Nistune. My own S13 KA24DET gets 400+ miles per tank full on the highway crusing at 90mph moreless. I know a lil somehting about what im talking about.

[Chris28]

UNISA I didn't know you were on Nico.

Off topic, but the info you provided about the knock sensor issues on other forums is outstanding. Helped me out a lot when troubleshooting.

[UNISA JECS]

UNISA I didn't know you were on Nico.

Off topic, but the info you provided about the knock sensor issues on other forums is outstanding. Helped me out a lot when troubleshooting.

Thanks, Im glad its helping people cause alot of people end up replaceing the knock sensor and 9/10 thats not even the problem its the harness that shorts to ground, thats a toughy one right there that I can diffenantly see stumping people.

[Turbo_mits]

Thats because the walbro 255lph over runs the stock fuel pressure regulator, what yoru experience is normal, you need to buy an adjustable fuel pressure regulator and reset your no-vacuum present fuel pressure to 43psi.

Normally with a walbro 255lph the fuel pressure is bumped up 6-9psi which is a hell of alot, running at that much more fuel pressure would require a retune cause your fuel pressure is at about 3 1/2 bar, im speaking from a self tunners perspective, I tune alot of my friends cars with Nistune. My own S13 KA24DET gets 400+ miles per tank full on the highway crusing at 90mph moreless. I know a lil somehting about what im talking about.

Thanks buddy, very helpful!