1990 Nissan 240SX not starting after replacing fuel injector

[Dr.Nurse]

Today a friend and I performed the following tasks in order to solve the problem of a leaky fuel injector code on a California Model 1990 Nissan 240SX. The car ran prior to our interventions, but now it has ceased to start for some unknown reason.

1) Replaced the Fuel Injector Connectors via butt connectors and solder because the existing ones had exposed wire and severe corrosion

2) Installed Rebuilt Fuel Injectors with Fresh Seals and O-Rings (Had the injectors rebuilt by Mr.Injector out of Idaho)

3) Replaced the Fuel Filter and Fuel Pump

4) Installed a Fuel Pressure Gauge between the Fuel Filter and Fuel Rail in order to perform future diagnoses.

After performing all of the aforementioned, the car will not start. When I turn the key on to activate the fuel pump, although initially the fuel pressure gauge reads about 43PSI, it quickly goes down while I hear a swooshing sound near the fuel rail. None of the injectors are leaking. No Fuel lines are leaking. It seems to me that the culprit is a faulty Fuel Pressure Regulator but I am hoping that someone with more experience the this matter can shed further light on my dilemma prior to me spending the extra bucks.

Thank you for your kind consideration and any information that you may offer in my plight to smog my car before the Spring Semester begins.

Sincerely,

-Brian

[PapaSmurf2k3]

Yeah, it kinda sounds like a bad fuel pressure regulator, or poor connection at the fuel pump. Does the car even sputter?

You can always just try swapping the old fuel pressure regulator back in too. Also, sometimes it takes a minute to clear the air that resulted from changing the filter and purging the rail, etc.
How many times have you tried to start it?

[Dr.Nurse]

Hey, thanks for the reply!!

So the following day I went back to the 240sx to rule out a malfunctioning fuel pressure regulator. However, upon cranking the car it started flawlessly.

Is it possible because we disconnected the battery overnight that perhaps clearing the ROM on the ECU got rid of the problem??

Even stranger is that now when I turn the key, (without starting) the fuel pressure holds constant at 43psi and there is no whooshing sound coming from the fuel pressure regulator. I don't understand how clearing the ROM could have caused this since all the ECU does is tell the fuel presssure regulator sylanoid to either allow vacum from the motor or not. Since the engine is not running then the regulator should be closed.

I think your explanation also deserves some looking into; because the fuel rail was full of air perhaps the air had an easier time passing through the regulator than the fuel. Still doesn't explain why letting the car sit overnight with the battery disconnected solved the problem.

Anyway, the check engine light is off and I am happy as can be. I am going to drive the stale gas out of it today and take it in for a smog.

Thank you,

-Brian

[PapaSmurf2k3]

Maybe the battery being disconnected is just a coincidence. Who knows. Glad it worked out.

[Dr.Nurse]

PapaSmurf2k3,

Thank you for your help in my plight!!!


Earlier today I took the car down and got it smogged and to my surprise, the smog tech was adamant to comment on just how well it passed for the millage (>250,000miles).

However, ironically enough, once the car passed smog and the smog tech turned off the motor, the car would no longer start.

I was able to get a jump start and took the car back to my friend's house to diagnose the problem.

With a voltmeter on the battery, we tried to turn over the engine. The volts dropped from approximately 12.8 to 0.1; the battery was toast.

We then proceeded to install a functional battery. Afterwards we started the car and checked to see that the alternator was charging the battery; it was. While the car was running, it read 14.6 volts and would rise a bit upon acceleration. From this we inferred that the alternator was functioning as it should.


However, while the car is at rest, with the positive battery terminal connected, and the negative battery terminal disconnected, there is an approximate .067milliamp drain going from the negative battery terminal to the ground strap. Because of this, we resorted to leaving the battery disconnected until we could identify and remedy the drain.

Q: Do you have any suggestions for how to diagnose such a battery drain? We were thinking about going through the fuse box and systematically pulling fuses until we could see that the battery drain cease; using this strategy as a guide to pinpoint which section of the electrical system to target.

Thank you in advance,

-Brian

[PapaSmurf2k3]

That's the exact method I used.
Pull the fuses 1 by 1 (although I started with the usual suspects - radio, clock, etc). Then when you find the circuit, start pulling the devices on that circuit.

I ended up having to run a new wire from the fuse box to the back of my radio. I still had a drain even with everything disconnected, so one of the wires had a little mini-short going on.

[PapaSmurf2k3]

Make sure your door is closed while you're doing it too.

Also, I noticed my car had a power-up sequence type thing. It would read something like .7 amps for a minute or so, then drop down to .1.