Need help, my 92 240sx wont work!

[blakerobin]

I have a 92 240sx convertible, 174k miles. Bought it, worked well for a few months. For the last 2 months, it has been shaking really bad, then 6 weeks ago it died. It rolls when starting it, and sometimes starts, but will never stay running for more than 10 seconds. I have change the spark plugs, wires, rotor, distributor cap, the 4th fuel injector, fuel pump, fuel filter, throttle position sensor, and removed the gas tank and power washed it out, put it back in and then put new gas in it. It STILL doesn't work. I took it to the dealership after I replaced the filter and they did the sensor and gas tank cleaning. They're stumlped as am I. Kinda hope someone on here and shed some light. They think it's something fuel related because everything else checks out. All I know is that this has been very frustrating and I need it fix ASAP.

[biggie]

Engine been compression tested?

[blakerobin]

Not that I know of. They seem to think that it's some sort of fuel problem.

[biggie]

Changed the fuel pressure regulator? Or buy an in-line fuel pressure gauge to make sure it is correct (34psi at idle with vaccum, 43 at idle without vaccum).

[blakerobin]

So they called me today. They tested the injectors and they're not the problem. They're going to spend the rest of today and tomorrow morning testing the PCM to see if that's the problem. Any ideas?

[biggie]

If not fuel, then spark or air would be the next things to test.

I still would want a compression test to make sure the engine is good.

[blakerobin]

They checked the pcm, they say that's what the problem is becuase the rest of the engine checks out okay.

[biggie]

I may be losing it, but what's PCM?

[blakerobin]

Lol, I'm not quite sure...I feel like he means the ECU...I think thats another name for it maybe?