'93 240sx electrial issues, please help!

[Newcastle82]

Ok, so here's the problem.

Just converted my '93 Nissan 240sx coupe to 5spd, but I don't think my electrical issues are swap-related. I posted previously about this same car having dash / interior electrical problems, and those have been fixed; there were two plugs on the fuse box that weren't plugged in at all. Done.

Now what's going on is this... I can start the car, and it warms up just fine, no problems at all. When it's warmed up and I give it a little cash to drop the idle down, the car stalls out, and dies. The revs drop really low the more I open the throttle, and when I eventually do get off the accelerator peddle, the car will continue to rev lower and lower, until it finally sputters and shuts off. I turn the key to the off position, and I get a buzzing noise coming from the engine compartment.

I've tracked the buzzing now to the relay/fuse box behind the battery, and subsequently to the EGI Relay (See Photo). It makes a wierd buzzing sound and vibrates, and the sound won't go away until I either pull the relay or disconnect the negative battery terminal.

I've checked all the wiring on the transmission harness to make sure there isn't a pinched/crimped wire somewhere, and it all seems to be fine. All the sensors, as far as I can tell, are plugged in correctly and the vaccum is run properly.

What is going on, guys? Help! I have to sell this car and I can't get it running right long enough to pass a smog inspection, or even think about driving it to a smog tech. Anyone have any ideas??

[AX75F92]

Try replacing the relay or jumping the fuse with a paper clip.Your fuel pump is shutting off.

[Newcastle82]

Okay, so when you say fuse, are you talking about that entire green 'relay' ? I was under the impression that was relay, and not a fuse. Either way...

I tried replacing the green relay / fuse, and same deal. Car shuts off when the throttle is opened too far, sputters, and dies. Buzzing sound coming from the relay.

[AX75F92]

Yeah. I just meant you could try to bypass the relay and jump the connection using a paperclip or something (but if you replaced the relay, I doubt that is the problem). Is your fuel pump priming before you start the car? It sounds like you are loosing power to the pump. Go over the fuel pump wiring and make sure everything checks out. Maybe have a friend hold the multimeter on the pumps power wire and monitor it as the car is sputtering.You could also swap your AFM out with another just to make sure it didnt take a crap on you.

[Newcastle82]

Sorry, don't mean to sound like a nub, but... AFM ?

[AX75F92]

Air Flow Meter.

The device directly attached to your air filter. If that part goes south (and they have a history) it is common for the engine to die out or sputter on deceleration or quick jabs of the throttle in neutral. I would try swapping it out with a spare just to test it.The noise coming from the relay seems like it really could be a fuel pump wiring issue.