ISPKI

I went through and started testing the AFM via the "engine will not start" section of the EFI bible. Testing for resistance on the various circuits going through it. I am not entirely sure I am doing this correctly as the voltmeter reads 0 or 001 on all tests. When testing for resistance on these circuits (lets say the air temp circuit - should read 100 ohms) I should set my volt meter to "200" on the dial correct? And when testing for water temperature resistance, (should read around 2250-2750 ohms) I should have the dial set to "2000" correct? That is what I did and it failed on all tests except continuity from pin 8 to pin 9.

AH hah, Found it. looks like they go to cooling fan sub harness - BE-95, Detail E, #16. Quick question: Is the side of the main ignition relay that switches on when the key is turned to "start" supposed to stay closed while the key is turned or is it supposed to click very quickly?

Here are a few shots of the wires that I am trying to figure out. One is a bullet connector, the other is a spade connector, both female. I can find where they are supposed to go. This is on the passenger side. I also found a plug disconnected on one of the relays in that cluster on the passenger side, above the fuse box. A 6 pin connector with 3 pins in it.

ECU looks brand new inside. I was scrounging around and found two disconnected wires over on the passenger side dangling down from where the engine harness comes through the firewall. One was white with a red stripe and the other was solid blue, about 14ga, both had bullet connectors. Not really sure where these are supposed to go but the white/red striped wire has continuity to the large wire going to the alternator from the battery. No idea where the blue wire goes but seems really odd - those white/red stripe wires are usually really important... Will investigate more when I get into it this weekend. I just had to fabricate a new exhaust system for my honda civic before winter hits so that has been sucking away alot of my time.

If it is what you want to do, then do it. Making your car unique to your liking is never a bad idea but, you have to do it right. Plan out exactly what you need to do and what equipment you need to have before getting into it. If you do a crappy job on it, it will look like garbage, if you do a great job, everyone will be impressed by it.

As Tony said, the injectors are already wired into the battery through a dropping resistor and a fuse. They receive battery power all the time when the key is "on". You can ground out each injector by finding the correct pin on the ECU plug, stick a wire into it and then tap it on a ground with the key "on". The injector should fire every time you tap the wire.

I would love that zed, unfortunately I live in CT and people here do not believe in things like datsuns, freedom, happiness...did I mentions datsuns? Seriously, it took me two years to find this one. I am going to pull my ECU out tomorrow and take it apart to see if anything is damaged inside.

Well I went back and tested the injectors individually. I slipped a wire into the #6 pin on the ECU plug (pin#31 I believe), turned the key to "on" and tapped the wire against a bolt by the pedals. I could hear a very faint clicking sound from the injector. Also - Just to make sure it was firing, I checked the fuel pressure before and after grounding. The pressure before I started was at 30 psi, I clicked the injector maybe 8 times and the pressure dropped to 21 psi, then I kept checking other injectors and it dropped to 0. This confirms that the wiring harness from the battery, through the ignition switch and relay are all intact and that basically leaves the ECM as the only possible issue. I will order one tonight unless anyone has any other ideas of what might be the issue. Also - Does anyone have a good source for these? Remanufactured from Rockauto costs about 250$.

Well I plugged the open relay back in and started the car to see if the relay functioned. It does engage both contacts, the one that engages when turning to start just doesnt click as loud as the one when turning to on, and it does not engage when the wire is disconnected from the starter solenoid which must be why I did not feel it click before. So just to clarify where I should be in the EFI bible - My vehicle will start for a second after sitting over night and then die. After that, I cant get it to start although it does sort of cough every few seconds or so. I was looking under "engine does not start" but maybe there are other tests elsewhere that I should be doing. Anyways, I am trying to test the ignition lead wire (a step that I skipped previously), just waiting for the rain to let up...

I have a pressure gauge right at the start of the fuel rail, after the fuel filter. Maintains about 37ish psi. I have spark, I do not have injector pulse. It starts and runs with starter fluid but dies as soon as I take away the fuel source. I tried to fire the injectors manually by tapping the negative terminal on the coil to ground but the injectors did not click. So far, all my tests point to the relay as all the circuits that have failed pass directly through the relay but I don't see anything wrong with the relay itself. Nothing appears damaged inside of it. I think I will need to simply buy a new unit just to test and see if that is actually the problem... does anyone have a source for these? I have only found one and it was quite expendive .

Well, I dont see anything really wrong with the internals of the relay, its all very clean inside.

OK, I went back to the FI handbook and rechecked the ignition relay. It clicks when turned to "on" but does not click when turned to "start". This lead me back to double check Pin 4 on the ECM which I believe is just the wire that supplies power to the ECM? In the schematic, Pin 4 should have a wire that goes from ECM -> Relay, Relay -> Ignition Switch, ignition Switch -> Fuse, Fuse -> +BAT. Since I jumped the starter with the key turned to "on" and it did not want to start up and run, that basically narrows the problem down to the ECM or the Relay correct? I know the fuse and the cables are good up until it gets through the firewall and into the relay. I think I am going to try and pull the relay out and look inside it to see if there is any damage inside. Going back and double checking some of the other circuits that go through the relay and others are also failing - Pin 20 to ground has no continuity, pin 34 to ground also has no continuity. Looks like the relay is the source of my issue here. Will know more once I take it apart.

OK, I checked power to the injectors with my multimeter by sliding the red probe into one pin on the injector plug and the other I wedged between the valve cover bolt and the cover, no power before turning key to "on", 12v with key turned to "on" and 12v with key turned to "start". I jumped the starter with the key turned to "on" for 4-5 seconds and, as usual, it started for a second and then immediately died.

Looks nice man. I have to do the same firewall/battery/fender/floor repair on my 77 280z so I am keeping your photos handy as a reference.

Right. I am going to take closer look at the ignition switch tomorrow morning. I do rebuild it with new parts as the original was broken and was very hard to get the key to engage. I recall that the switch assembly did not really go together nicely with the aftermarket components so maybe there is an issue there. Thank you BTW for all the help thus far.

Looks like I am getting 0.4ohms on all the injectors. I have continuity to ground from (I think) pin 72 on the relay - I tested the only black wire coming out of the upper plug. I also tested pin 21 and 34 (cold start circuit and air regulator circuit) and those both failed to have battery voltage with key turned to "start".

I have continuity on pins 5, 16, 17, and 35 now. I have +12v on pin 10 with key turned to "on" but I do not have 12v on pin 4 with the key turned to "start". Currently testing the injector wires. Trying to figure out if they are in the correct order or if I have the wires flipped. What should the resistance be on the injector wires? I was getting very low resistance Do you guys know which connector on the injector is supposed to be receiving the 12v and which one is supposed to connect to ground?

Of course, some of those pins on the plug are damaged, cant be good...will straiten them out when I get to it.

I did not get a chance to check the resistance but I will do that today. Here are the photos of the ECM and ECM plug. I dont recall which end to start counting from but some of the pins are not lining up. I looked online and that appears to be how they are configured, just seemed odd to me. I am leaving now and will continue testing and report back later tonight with results.

Well I located the ground wire on the intake. It was in bad shape so I cut it out at the point where the three smaller wires connected from the harness and soldered in a new wire. Still cannot start. I was looking at my ecm and noticed that there are pins on the plug for the ecm that do not have pins matching up to them on the ecm side.

Been a while since I updated this. I decided to remove my old manifold and rusty exhaust piping. I purchased some MSA 6-2-1 headers new, used a chemical stripper to get the paint off and painted with Rutland's stove and chimney paint. Looks alot better than I expected, has been on the car for a month or two now and no rust. I picked up 5 feet of stainless 2.5" pipe, a Borla Pro-XS muffler and some Torctite clamps to run the exhaust straight back and then out the side behind the door. Sealed the clamps with permatex. I also made up some exhaust hangers with these cool vibration dampening clamps from mcmaster and a SS threaded rod. While I was removing the manifold, I found the PCV hose was literally falling apart on the car - perhaps this was my issue with the engine not running very well? I picked up a new PCV, new SS hose clamps (I got a thing for SS) and a NOS flared hose. Bolted the new header up aaaaaand now it wont start. I have spent the last three weeks trying to find the electrical problem. Everything checked out but the injectors were not firing - not being grounded by the ECU. I finally found that the ECU has no connection to ground on pins 5, 16, and 17. Will be tackling these next.

I went back and tested the ground connections for the ECU plug. With one end of my multimeter stuffed into the plug on the battery terminal, I tested slot 5, 16,17, and 35. I have no continuity on 5, 16, and 17, but I do have continuity on 35. Guess I will be hunting down ground wires for the rest of the week.

I picked up a small bulb from the parts store - 12v, 3.5watt. Wired it up. I checked it by plugging one wire into the + side of the #6 injector plug and touched the other wire to ground, bulb lit up nicely. I plugged the ground wire into the other side of the plug, turned key to "on", then to "start" for a few seconds and the bulb does nothing. So, this tells me that the ECU is not grounding the injectors...but why? Is there any other reason as to why the ECU would not ground the injectors besides the ECU being damaged internally somehow? Is it possible that the actual wiring from the injectors to the ECU is damaged? I will search for the wire schematic but I am running out of time today so if anyone could fill me in on where the ground wire for the injector goes or what else it runs through between the injector and the ECU? It does not look like it goes anywhere except to the ECU and then the ECU grounds to the -BAT terminal correct?

I will stop by the ca parts store tomorrow and snag an interior light of some kind and test the injectors out.

Thanks for that tip CTC. Would a turn signal bulb or dome light bulb work? I assume those are fairly low wattage, especially the dome light.