Hello! I have a 1975 280Z that has been in storage for more than 20 years. I have dipped the tank, cleaned the fuel pump, replaced the fuel filter, drained and refilled the oil and coolant, etc. The car will turn over and catch but then stalls out. I can do this maybe three times and then I will have to wait for 5 minutes before being able to do it again. After the third time of starting the car will just turn over.

I have the bible and have gone through it step by step.

I did not have another person to listen to the injectors though. I did all of the tests as if the injectors were clicking and as if they were not. All tests were good.

I tested the AFM. All I found wrong was that instead of having continuity with minimal resistance between 7 and 8 I actually have 170 Ohms. I did not think this was a big deal since as soon as the motor starts the AFM comes off of the point where it is reading 170 ohms.

The temp sensor test seems good. 380 ohms with it being about 60 degrees.

I also think the power relay is only clicking once but the tests in the bible are good.

I placed an in line fuel pressure meter and I get 40 - 42 psi.

I did try just holding the key into the start position and the car ran for a bit longer with the starter turning. After that though it did not start again.

I figured that the car was only running on the cold start injector. After holding the key in the start position and not getting the car to start again I took out the cold start injector. It had a bit of fuel on the end. When I tried to start the car with the injector out though I got no fuel flow from the injector.

The tests that I have done seem to indicate a bad controller but I want to make sure before I drop the cash. Any sure way of know if the controller is bad? Anyone in ATL have a spare to lend?

Is there a way to make sure the injectors are not clogged? Can they be cleaned?

Thank you,

Michael

To see if your controller is bad, I suppose you could get a test light, and plug it into one of the injection plugs, then crank the car to see if they're clicking the injectors like they should. As for the injectors being stuck, I'm not too sure how to check that.

I got it running. It ended up being three injectors were not firing. I replaced those three injectors and she started right up. The car seems to be running rich but I will wait awhile before diving into that.

Napa has some good tools that were very helpful -

Noid light. Plugs into the the injector plug and flashes when it gets the injector firing signal. $18.00

Fuel injector tester. Attaches to the injector and sends pulses to test the amount of fuel the injector is flowing. $179.00

I will continue to install the lights and make the car road legal and hopefully be able to drive it this weekend.

M-

I got it running. It ended up being three injectors were not firing. I replaced those three injectors and she started right up. The car seems to be running rich but I will wait awhile before diving into that.

Napa has some good tools that were very helpful -

Noid light. Plugs into the the injector plug and flashes when it gets the injector firing signal. $18.00

Fuel injector tester. Attaches to the injector and sends pulses to test the amount of fuel the injector is flowing. $179.00

I will continue to install the lights and make the car road legal and hopefully be able to drive it this weekend.

M-

179 bucks? I made my own tools for the two functions you mention from some wire, a 9 volt battery, and some old EFI parts and spent the money I saved on a dual guage fuel injection canister cleaner and still had about $50 left over from what you spent. Those tools from NAPA are nice if you have modern fuel injection but really not necessary on the old Nissan EFI.

Hey Stephen,

Good job on the DIY test stuff. If I knew more about the efi and had the spare parts laying around I would try the same thing. As it is I was having a hard enough time trying to figure out what was wrong with the car without inventing tools too.

The NAPA guy said that as long as everything was squeaky clean I would be fine returning it.

I will use the returned cash to buy three more injectors to replace the other old ones. The car is running rich as anything. I saw a Honda Fit riding close behind to try and capture the fumes!

M-

A few things to check for running rich would leaking fuel injector(s) or cold start valve, bad connection at the temperatrue sensor or bad temperature sensor, improperly adjusted or bad throttle position switch, or bad fuel pressure regulator. I see you've run most if not all of those tests but the reading you give 40-42 psi is about 4-6 psi too high.

Hello Stephen,

Tonight I will check the spark plugs to see what they look like. If the back three are sooty then I will go ahead and change those injectors since they are the old one still. When I checked them they did not drip but that is not to say they weren't putting too much fuel in.

If all are sooty then I will run the car awhile and check the resistance between pin 13 and ground. When the motor is warmed up I think it should read near 300 ohms.

I will also check the air intake temp at pins 6 and 27. It should be near 2700 ohms.

The cold start valve may need attention. I guess that I could just disconnect the fuel line and see if the car runs leaner.

If that looks good I will adjust the AFM. It looks newer than the other parts on the car. When I tested pins 7-8 I got 170 ohms when it should be just reading continuity or a small resistance. The other checks were within range.

I'll post the results in case anyone else travels this path.

M-

You still need to see why your fuel pressure is high. 4 to 6 psi over the preferred regulated psi would be enough to make your car run rich. If you disconnect the fuel line from the cold start valve, malke sure you plug it well. I'd save that AFM adjustment until you've tried the other things you mentioned. Unless you have experience with that type of adjustment, that's an easy way to make things worse.

Hello Stephen,

I forgot to bring the multimeter home yesterday. I did remove the plugs and #5 looked darker than the others and #6 looked lighter. #1-4 looked good though. I replaced the remaining old injectors.

I forgot to mention in the last post that the fuel pressure is now near 34psi not 42 that I saw earlier. Not sure what the accuracy is of the gauge. Maybe since the injectors were not firing the regulator could not bleed off the pressure? Maybe running more fuel through the system will help loosen stuff up.

For the cold start valve I just pinched off the line with vise grips.

It seems to be running leaner. There is still a bit of a stumble at idle. It got a little better when I increased the idle speed. I have it at 900 rpm now.

I will take it out on the road this AM and see if there is any driving improvement.

I will save the AFM for last. When I do move it I will make sure there are reference marks so that I can reset everything.

Thank you for the advice!

M-

M-