Dieing issue

[matthewstratton1449@gmail.]

ok so i pulled plugs and cyl 1,3,4 have fuel on them 5 looks like it has light fuel on it while cyl 6,2 are dry plugs are B6ES NGK's. I also tested more circuits and found Air Flow Meter Resistance #2 3b test where small resistance should be found i found 185 ohms, also Air Temperature sensor resistance test #1 (4) was not reading any resistance, Air Regulator and Fuel Pumpp Circuit test #1 (8) had no continuity, Injector Circuit #5 Test #2 3(c) only had 11.1 volts compared to the rest at 12.6 volts besides on #3 Injector Circuit Test #2  3(e) measured only 0.01v wayy lower than the rest. So at this point i have no clue were to even start 

[Zed Head]

Actually, you're way ahead of most people new to EFI (no offense to most people).  You have a meter, you're using it, and you're getting real numbers.

1975 was the first year of EFI so Nissan's book wasn't the greatest.  Here's a later one that has tests for all of the years up to 1980, and has better numbers, than "small resistance".  You  have to pick through and find your year but they give more info.  Your 185 would be about 150 in the newer book.  Close enough I think.

I would focus on the Pin 1 signal.  Is the tachometer still in the car?  I've found that the whole circuit from the coil to Pin 1 needs to be intact for the ECU to open the injectors.  Sometimes the system own't work if the tach is disconnected.

There is a simple trick for checking the Pin 1 circuit that lets the ECU know when to open the injectors.  Connect a wire to the coil's negative terminal.  Turn on the key.  Tap the other end of the extra wire to ground.  You'll get a small spark as the coil circuit grounds.  Every third tap should cause the injectors to click.  That's what the ECU does, it counts sparks then injects.

 

[matthewstratton1449@gmail.]

so the original tac isnt in the car the previous owner put some crappy aftermarket one in, i attached a video doing the coil negative to ground but the most i could hear was ticking coming from what sounded like the coil or something in that area, im gonna re try when i have extra hands later so i can actually listen to each injector and originally when i pulled the harness i spliced into the pin 1 wire and ran a new wire from coil ground to ecu 

[Zed Head]

You should hear all six injectors click at the same time.  It's very hearable when the engine is not running or the starter turning.

It might be that your ignition system needs some work.  I think that you said it used to start then die, now it doesn't start at all?  Maybe recheck spark, then tune the ignition system if it's gone.  Do you still have the original ignition module?  It might be that it is dying also.  75 was only the second year of electronic ignition and the modules are very old now.  You're pretty close I think.  Reconfirm what used to be.

If you have lost spark there are some cheap and easy ways to upgrade to a better more powerful ignition system using a GM HEI module.  That module also got rid of the tachometer issue on my car.  Stronger spark and no injection problems.

[matthewstratton1449@gmail.]

Where would the ignition module be located i don't see anything in the engine bay some people saying its under the dash on passenger side 

[EuroDat]

It's on the passenger side forward from the fuse box.

[matthewstratton1449@gmail.]

found it looks like the original to me E12-08 

[matthewstratton1449@gmail.]

So i started checking for spark at each plug and when i got to to cyl 4 it constantly sparks even while car is not cranking just sitting with key in ON position, i noticed earlier that the in the coil area there was a constant click noise and i still couldn't for sure tell were its coming from but it correlates with the spark every time at the plug

[Zed Head]

That is odd.  In order to create a spark the circuit through the coil needs to be completed then broken.  It looks like the circuit is being "made" then being broken, maybe just due to overheating.  I'm going to guess that your ignition module or the ignition coil is bad.

When you turn the key on power flows through the ignition coil and the ignition module, something inside the module or the coil overheats and the circuit is broken, and a spark is created.  It probably happens on #4 because the rotor just coincidentally was pointed at the #4 terminal in the cap.  If you turn the rotor to a different spark plug you might get that plug to spark the same way.  Feel free, anyone, to critique my guess.

Since you already identified the coil as being out of spec. that's the easiest and cheapest part to try.  If you have a spare coil of any type it will probably work for a test.  If you want to try the GM HEI module there are some writeups on the site.  It's just four wires and a place to bolt it to a good ground.

 

[matthewstratton1449@gmail.]

So update pulled the injectors out and cranked it and have no injector action fuel pressure tested good kinda weird cause it was able to idle couple weeks ago and now its not giving injectors anything. Uploaded a video of it cranking with no response, so now im kinda just confused i have 2 ecus and 2 drop resistor bundles i can swap between and see if thats a issue but ive been doing that from the beginning.

[Zed Head]

38 minutes ago, matthewstratton1449@gmail. said:

kinda weird cause it was able to idle couple weeks ago and now its not giving injectors anything.

Break out that meter and rerun some tests.  Sounds like you lost power somewhere, or ground, or the Pin 1 signal.  Can't swap until you know what to swap.

[matthewstratton1449@gmail.]

So update i got a actual shop now and moved it to its now home, once there i pulled hood off again and started checking everything from start. I found the problem sooo previous owner did some jank wiring ending up switching the connections at the battery i stripped the tape and loom off to inspect the wires and trace and found out that wire number 70 which is suppose to go to the positive terminal was wired to the negative side and the few wires that were suppose to be connected to the negative side connected to the positive numbers 5, 16, 17, 35, 72, 49 after redoing that and cranked the motor would you guess it i have fuel from all 6 injectors instantly, redoing the coil negative to ground caused the clicking that i had not heard yet confirming the issue fixed. I used a picture to re hook up all the plugs and put injectors back in. I cranked the car and got a instant response of a rough idling then died, i adjusted the distributor a few times to no real gain just hard to start and rough idle till it died im not a 100% on fuel level after all this so im going to go back tomorrow and put more gas in it and try again but would my coil being out of spec also cause issue here i planned on going to O Reillys tomorrow and ordering the right coil