| Car history, just purchased and was sitting for a very long time possibly two years in KY 2 weeks ago Car came from general repair shop with replaced plugs, fuel filter, air filters, alternator, fuel tank flush trying to fight the extreme lack of power issue. Car came to me for extreme lack of power on a side job.
I have figured out it has a low fuel pressure issue. Fighting on/off for a week now. At first it'd bogg down at medium load or greater not being able to accel past 40mph unless very light throttle used, Idles Good, Slow high RPM gain.The hotter/longer car runs the worse it gets. I told owner it was cat or fuel issue. The exhaust was rusted(moderate chassis rust over all, and underneat rear area of car). So the owner basiclly replace exhaust behind manifolds and back. Car comes back with same issue, no better or worse Scanned and MAF completely STUCK at 3.6 volts. Installed known good MAF and fixed that issue about 1.2-1.6V @ idle and clean sweep up to 4V under accel. MAF only had a very slight improvement of idle smoothness AFM code only from bad MAF .no other codes , o2s banging back and forth lightning fast @2k RPM, injector balance okay good TPS voltage sweep, boost test with boost pro's tester to 10psi no issues Car runs only very slightly better after MAF. Hook up fuel pressure guage, good fuel pressure at idle 35-40ish. But well driving fuel PSI drops lower the harder I hit the gas down to 5-10ish PSI car bucks boggs down very violently. Install fuel pump. car drives good for one day and comes back
Double check my fuel pump install(fuel line from pump outlet to pump retaining assembly) I thought fuel could have been bleeding from this small line, i replace spring clamps with screw clamps to insure no leaking in the fuel tank internally. Then i install known good fuel pressure regulator, dampener, and recheck fuel filter. Car is runs strongest is ever has Can now hit redline. Car warms up and runs like trash all over again. Note the fuel in the tank is still nasty rusty and not see through like normal gas, the fuel pump bracket retainer was rusted. check Fuel pump signals 3 wires to pump, low and high speed, but 2 channel proble on, one on high, one on low, plus ground. Oddly i have a constant battery voltage to the pump idling and driving hard, Why no low speed lower voltage signal at idle? So i try known good fuel pump controller module, no fix. so hears a breakdown of attemps: initial fuel flush
MAF sensor nissan oe
fuel filter nissan oe
fuel pump Brand new nis oe
fuel pressure regulator and dampener nis oe
fuel pump controller module nis oe any suggestions why the car would have low fuel pressure after heat soaked Tomorrow I will test and monitor 02s, MAF, inj pulse width. with nprobe Monitor fuel and timing map position with Nistune
will try known good ECU. I hate part swapping but i've been lead down this road of attempts. Initially on my first drive i knew it was going to be a combo of causes, discovering bad MAF sensor, and dirty rusty fuel. Why is rust in tank, is there still moisture in tank. Can a warmed up fuel pump not pressurise dirty fuel? I will probably reflush it again. This one really has me stumpped, ;-) on top of it all its just a NA, NAs are supposed to be easier to work on. but this car is kicking my ass, I will update tomorrow noon or night.
Formerly SpecNATT (Houston)
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