Hello,

I recently got a 1991 300zx NA, just had the injectors replaced.

I've noticed a strange problem (which occurs intermittently of course). When i start the car up, sometimes, i will hear a muffled "beep" from the back of the car, it sounds like its coming from inside.

The beep lasts two or three seconds then stops. Whenever i step on the throttle, the beep starts, and stops when i let off the throttle. This occurs whether or not i am in gear/the clutch is engaged. Once i get going around 30 or so, the wind/road noise is too loud to hear the beep

I thought it was related to the aftermarket sound system in the car, which included an amplifier and a small subwoofer. I disconnected everything (so i have no sound system now) but the beep still happens!

I'm pretty sure its something electronic making the sound. Its a single pitch that doesn't rise and fall with engine speed, its its digital in nature (sound or no sound, no fading).

Could it be related to the rear windshield washer? The fuel pump?

I was certain it was the sound system until i removed it, now I have no idea.

Any help would be appreciated!