clicking relay, need help!

[95vr6man]

i have a 97 240sx that all of a sudden stopped working while i was out on the road, and now it wont start. the fuel pump relay clicks loudly and i replaced it with a known good one and does the same thing. i can mannualy open the relay and bridge the connection and the fuel pump comes on just fine but stays on but the ECU doesnt come on nor does it have power.. i know this cuz my safc2 does not have power either and its powered from the same relay as the ecu which is the eccs relay according to my schmatics.

i think the problem is the eccs relay maybe but im not sure where its located. the ecu controlls the turning on of the fuel pump right? like grounds out the fuel pump relay, this is what i understood but i might be wrong.

what should i test or is there anyway to hotwire power to the ecu so that it will turn on so i can atleast get it back to my house. thanks!!!

[vancouverbc]

Check your fuses. Relays click when they are working. It's like a drawbridge lowering to complete the connection. Check for a spark.Can the car be jump started? Push started? What is the condition of your battery? Did you have any symptoms consistent with bad alternator?SOme of what you are saying is right but you are basically going on wild goose chase.

From the EF (Engine Fuel) & EC (Emission Control System) section - Diagnostic Procedure #5 / Hard to Start or Impossible to Start when Engine is Hot:** Fuel Pressure - Squeeze the line coming out of the filter and to the engine when cranking the car. You should feel pressure. No = Check the fuel pump and it's circuit. Yes = Continue

** Check Fuel Vapor - Disconnect fuel pressure regulator vacuum hose and plug the hose. Can you start the engine? Yes = Check fuel properties (don't know what this actually means) No = continue

** Check Injector - Remove crank angle sensor (distributor) from engine. Be sure to note the location and orientation of the rotor before taking the CAS out of the engine. It needs to go back the same way (Crank angle sensor harness connector should remain connected) Disconnect ignition coil harness connector. Turn ignition switch on (Do not start engine) When rotating crank angle senor shaft (distributor), does each injector make an operating sound? No = Check injectors and circuit. Yes = Continue

** Check Ignition Spark - Disconnect ignition wire from installed spark plug. Connect a good known spark plug to the ignition wire. Place end of spark plug against a suitable ground and crank engine. Check spark. No Good = Check ignition coil, power transistor unit, and circuits. Yes = Continue

Check ECU Harness Connector

Check ECU Power Supply and Ground Circuit.

Basically, what's being looked at here is if the engine is getting fuel, the injectors are injecting and the spark is sparking. The ECU part is standard fare in diagnosing our car.

[95vr6man]

alright, i still think its the ecu but here we go.. the there is ONLY fuel pressure after i manualy turn on the fuel pump cuz it wont go come on any other way, the injectors are not getting power, i have one of those injector light kit thingys. ive checked a buttload of fuses but forgot my multimeter so it was a visual inspection but ill try with the multimeter today. also, there is no spark at all and the safc will still not come on nor will the check engine light when you turn the key to on.. isnt it supposed to turn on then? but everything else works stil.

oh yea i had just hit a bump when all this happened if that means anything.

any other things to try? thanks for ur help so far.
Modified by 95vr6man at 5:29 PM 10/2/2006

[vancouverbc]

Does your starter try to turn over? I think it should come on regardless of condition of ecu. I assume it is as your fuel pump is getting power and your fuel pump gets power from ignition switch. If your battery is good check the ECCS relay and related fuse link. Fuse links can be blown and you cant tell without mulitmeter. The ECU does control when the fuel pump relay is on.

[vancouverbc]

The 1997 factory service manual is available here, btw:

http://carfiche.com/manuals020/cars/

Modified by vancouverbc at 3:12 PM 10/1/2006

the pic is from section EL location of electrical units.
Modified by vancouverbc at 3:13 PM 10/1/2006

[95vr6man]

thanks alot for the info, yea those factory service manuals help alot, best invesment ive ever made.

i traced it down to an overlooked engine bay fuse, the 7.5amp ecu fuse.. i replaced the fuse and it worked again but as soon as i started to drive the car it died again and blew the fuse. i checked it with my multimeter and one side of the blade has 12v(from the battery) and the other side is showing 12v ground. wich means that the wire is grounding out somewhere between the fuse and the ecu relay or ecu. could the eccs realy ground itself out thus blowing a fuse?

[vancouverbc]

I assume you are referring to the blade in the fuse. I assume you connected one side of multimeter to 12v+ source and other probe to one side of fuse and got 12v+ reading on multimeter, suggesting ground is at one end of fuse?

I dont have a lot of experience with tracing down shorts. One possibility is that the relay coil is burnt out and conducting ground from the ecu. Turn off the ignition and see if ground is still at one side of fuse. If no , you know relay coil is conducting ground. With ignition off, the ecu wont be sending ground to relay. Next, pull the relay out, and see if ground is still at the fuse. Pretty sure the ground will still be at the fuse.

Next, with the ignition off, measure the voltage at each of the terminals of the relay. You will have to pull relay out for this test. There should be neither ground nor 12v+. The fuse is open. I assume two of the terminals will read ground. From here, i dont know what to do . I would unplug the injectors one-by-one to see if short goes away. I would look for loose wires and wires with plastic coating scraped off. I would look at the connections to eccs relay and harness connectors.


Modified by vancouverbc at 8:14 PM 10/1/2006

[95vr6man]

wow looks like i have a big day tomorrow

thanks for all your help though i really appreciate it, ive tottaly rewired an rx7 with all my own relays and such before so i might just use one of my spare 30amp relays and a 7.5 inline fuse and power it that way so i can atleast get it back to my own garage cuz i dont have a trailer.. i cant see a downside of doing this other than having to splice a wire but that really isnt that big of a deal to me.

thanks for all your help!

[95vr6man]

ok wow im an idiot. i think i figured it out.. turnes out my ecu was loosly bolted on to the car, i tightend up the bolts on it and i guess grounded the ecu better and everything returned back to normal.. werid.. but atleast i got it back together and running. thanks!

[vancouverbc]

Thanks reporting back on what happened. I guess the bump did play a role.