Hi All, Newbie with a problem

[obxg20]

Hi All.
First of all, it's great to be here and seeing the wealth of information you guys have. Now I have a question and sure hope we can figure this out.

[obxg20]

oops wrong button, Anyway my question is this. I recently bought my son his first car which is a 95 g20. He loves it and it is a great car for him. I bought it knowing it had a problem, pretty confident I can figure it out as I am pretty experienced in car repair. This car ,when i start it, will start, then run for about 15 seconds then quit. does not always do this, sometimes it starts and runs fine. I have cleaned the iacv, maf replaced the distributor, fuel pump and filter, ignition switch, checked tps. Once It would not run and i got pissed and smacked the dash and it started and ran. once I moved tilt wheel up and down and it started and ran. then there have been other times when this did not work. it is totally random, it may start and run right now and may not, but start and run 10 min from now. It is really starting to drive me nuts. Please if anyone has any ideas, please share them with me. I have searched and found some related issues but never no real fix. The tach is also erratic at times and none working at others. please help. Thanks

[Q451990]

to NICO!

I wonder if you're not having an issue with the ignition switch or wiring in that area? You have already addressed the usual MAF and fuel pump suspects.

I'm guessing there's a wire that has 12V from the ignition switch that you could probe to see if it drops out when the car won't run...

You can check out the factory service manual (FSM) at http://www.nicoclub.com/FSM/

Good luck!

Heath

[obxg20]

Thats possible, also leaning towards a bad ecm. Thank you

[obxg20]

Oh, Maybe this will help some. It acts like the fuel is being cutoff by something. if I spray carb cleaner in air intake when it will not run, I can keep it running, but as soon as i stop she dies.

[goody90q45]

There's only a few components in the fuel delivery system of the G20- Ignition switch, ECU, fuel pump relay and the pump. See page EC-202 of the FSM.

http://www.nicoclub.com/FSM/G20/1995_G20/1995_G20/

You probably should do some checking with a voltmeter to see if power is being cut off to the fuel pump before the relay or after the relay. I didn't search the FSM to see where the relay and fuel pump connectors are but I'd lean towards checking the relay before replacing the ECU. See the "Location of Electrical Units" section to find the relay.

Good luck.

[obxg20]

Well what led me this direction was I did the test on ec-82 at pin number 8 on ecm and received the c rrect voltage for the first 5 seconds but then received no voltage after 5 seconds. Did all the tests on ec-204 and found no output signal, so checked connections and tightened the main harness bolt then I had a output signal. Changed the relay and still did not test correct at pin number 8. I sure am leaning to the ecu being junk. Thanks for all the input and if you have any other ideas please get back to me.

[obxg20]

Also the other day when i had my code scanner connected i had a 02 sensor code and cleared it. today when I hooked it up it could not find the ecu. Where does the aldl get it s power from anyone know? maybe ecu?

[obxg20]

And another question. Where can I find one ?any clues?

[goody90q45]

If the key is turned to the ON position and the engine is not started the fuel pump will run for 5 seconds to pressure up the lines and then the relay is there to turn off the pump. I'm pretty sure this is one of the standard relays (blue?) so you should have been able to swap it out with one from the fuse box to verify it was working properly.

The pin on the ECU that doesn't have voltage may be the one that feeds the relay and isn't supposed to see voltage after 5 seconds. Before you buy an ECU you might start a thread in the G20 forum to see if other owners have had similar problems. Check the Infiniti Parts and G20 forums for used ECU's. Ebay should have one also.

I helped a local owner fix a similar issue that turned out to be a loose fuel pump connection inside the tank from a previous owners pump replacement. The engine would quit but there was still power to the pump. Is yours the original fuel pump or has a previous owner changed it out?

[obxg20]

I have changed the relay with new the fuel pump is 4 months old by previous owner and is working ,I checked. the pin on the ecu is supposed to have .07-.10 volts for 5 seconds then supposed to go to 12 volts acxcording to fsm. it goes to zero volts after 5 seconds. I have been to g20 net and have'nt recieved much help as of yet and have seen others with similar problems attributed to ecu. I wonder if I was to run a seperate wire on a switch just to see if that works?

[Q451990]

Sounds like a good idea, as long as you're not feeding voltage back to the ECU. www.car-part.com is a good source for used parts as well... I wonder if the G20 shares an ECU with a Sentra of the same year?

Heath

[obxg20]

yes it would be nice if something else interchanged

[obxg20]

thats what i was worrying about. Don't want it to screw nothing else up.But I figured that since I have the dash apart, i could tap off the run side of the ignition switch and run a wire straight to it. the ground is already there.

[obxg20]

well ,the wire to fuel pump did not work. same problem. Damn

[obxg20]

Anyone have an idea why I have no power to the ALDL connector to my scan tool? All fuses are good.

[Q451990]

Makes me go back to my theory on something wrong with the ignition switch or wiring in that area. Maybe the Consult connector is powered on the same circuit as whatever isn't getting voltage in your fuel system?

Heath

[obxg20]

well everything tests ok with the switch. The connector i am talking about is not for the consult, it is on the pass side and it is for a generic scan tool. The thing is it did work when the car ran. but now it is having one of its fits and will start but shutoffs in 5 seconds and the svcanner will not read it. just wondering if the two are connected.

[Q451990]

Hmmm... I didn't know they had more than one diagnostic connector. Is there a "without consult" method in the FSM that you can use to check for codes? It usually involves turning a screw on the ECU and counting flashing lights.

Heath

[obxg20]

Yes there is exactly like you said with turning a screw and watching a light but to be honest that did not work either. The one time I was able to use my scan tool it came back with a o2 sensor, but now since it won,t run , It will not find ECM. I am thinking they are tied together and believe if my tool could find the ECM, bet the car would run.And I believe the diagnostic link is powered from ECM.This car is too nice to freakin give up on it and my son really likes it.

[Q451990]

Is the ECU getting voltage?

Heath

[obxg20]

yes it does have voltage.

[Q451990]

I'm beginning to wonder if you're on to something with your bad ECU theory. Does the car show any signs of repaired body work in that area?

Have you gone through the power supply test for the ECU power supply on EC-88 and EC-99?

Heath

[obxg20]

yes I have checked that out and it all tests ok. I have checked everything. I have the back seat out ,the dash tore apart, checked every damn sensor, I have run out of stuff to check, I really think it is the ecm. What else is there?

[Q451990]

At $25 plus shipping on www.car-part.com I would think it's worth a try...

Heath

[obxg20]

What is 25 plus shipping?

[Q451990]

I saw ECUs on there for $25 plus whatever they would charge to ship it... You can sort the search results by price and then scroll down to the cheapest one.

Heath

[obxg20]

Thats what i figured you meant. Well I did find one on ebay and of course it had the wrong connector and I am returning it and waiting on some info about one on car part.com.
I will let you know how things go.

[obxg20]

Well I finally found a correct ECM. Matching numbers and all. Plugged her in and car came to life and runs fantastic. Thanks for your help and info. I will be back.

[Q451990]

That is awesome news! Thanks for letting us know.

Heath