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HATchTRICK
10-02-2012, 06:22 PM
95 s14.
S14 sr20, walbro 255, stock fpr. Just replaced filter too.
The pump primes as key is turned, then only builds up to 15 psi. Idles rough then dies. After dies it will not start back up.
Unplug the maf and it idles beautiful but will not rev above 2000-2500 rpms.

Bad fuel pump?
hotlavaflow
10-02-2012, 06:26 PM
Could be, I bought a Walbro 255 for my KA-T and it was bad. Car started but wouldn't hot start (it would fail after warm). I swapped it with a Walbro I had for my Acura and no problems after that.
team13
10-02-2012, 06:54 PM
I was reading that fuel pump r bad with low fpr reading if was reading high it would be a sticking fpr.
Hardie
10-02-2012, 09:18 PM
When the MAF is unplugged the ECU will only let it rev to a maximum of 2500RPM as a failsafe, so that isnt a problem.

Have you checked your injectors?
Also check that all your plugs are firing.
fliprayzin240sx
10-02-2012, 10:03 PM
It could still be a bad, wide open fpr...
beems240sx
10-03-2012, 09:42 AM
sounds to be a bad fuel pump. in my opinion walbros really are not that great. ive had 5 or so break on me in various cars. they burn up quick if they are not submurged in fuel for cooling. reason it will run better with maf unplugged is that the ecu will be in limp mode and just DUMP fuel, and in your situation cause it to run like normalish. i would just do a new fuel pump and aftermarket fpr but thats just me.
Croustibat
10-03-2012, 10:01 AM
15psi is strange, dead FPRs usually have "no" pressure. Is your engine fitted with a hot start solenoid ? If so bypass it and connect your FPR directly to your intake manifold.

As for the fuel pump, is the noise regular, or can you hear it change ? Can you also check the voltage at the pump ? Sometimes the wires are too thin, and it makes a voltage drop. But even with low voltage, the pump should be able to make 3bars at idle (although only around 2.3 will be shown, as fuel pressure is intake pressure + 3 bars, and intake at idle is around -0.7 relative )
s14boy
10-03-2012, 10:30 AM
the fuel pump could be going but i would also check the maf with a mulimeter to rule that out.
beems240sx
10-03-2012, 10:34 AM
you can also check the resistance of Ohms on the fuel pump. if it is very high, it is fried.
Croustibat
10-04-2012, 02:55 AM
the fuel pump could be going but i would also check the maf with a mulimeter to rule that out.

maf has nothing to do with fuel pressure.