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Discussion Starter · #1 ·
I have a 1983 Datsun 280zx. Cranks but doesn’t start. Have been looking, doing procedures, re-wiring, among other things. The previous owner DID say that water got into both sides of the car. I took pictures of the pcm out of the box. Top and bottom. I’d like to have an opinion as if this is enough corrosion to change my PCM. If it is, then off to the Junkyards.
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Passive circuit component Circuit component Green Hardware programmer Resistor
 

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hmm I did not realize this era had electrolytic caps, I think I see 2 of those (upright and polarized). The rest of the parts are high reliability, assuming no electrical hookup boo boos, like reversed battery leads..
 

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Discussion Starter · #3 ·
hmm I did not realize this era had electrolytic caps, I think I see 2 of those (upright and polarized). The rest of the parts are high reliability, assuming no electrical hookup boo boos, like reversed
I don’t think I ever hooked the terminals up wrong. Like I said water got in the car
 

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The caps do not look like they have any bulging, which would indicate failure, but your output transistors in the upper left cormer don't look healthy, especially the right hand lead of the one labeled T781. I would suspect a failure there.
 

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Good luck finding one for a 82-83, they seem to be unicorns. The 82-83 can only be used in those cars. Doesn't matter if you have an auto and use a manual or if yo have a California emission and run a federal but you have to use a 82 or 83 unless you make some modifications.

I have a 83 that was a no start due to the the ECU was injecting so much fuel it was flooding the cylinders. Read about it here.

1983 flooded so bad it wont start. Fuel in oil. Checked...

I could not find a good 83 ECU, I have 2 bad ones, and converted my car to run a 79-81 ECU buy adding the dropping resistors. Car runs GREAT. You need to do your FSM Fuel Injection checks to make sure its not something else. Do all the checks. I did them 3 times to prove to myself it was the ECU. There is no way to test the ECU itself, the FSM tells you how to check the wire from the ECU to all of the things the ECU is connected to and also tells you how the check each device individually. If you eliminate all other sensors then its the ECU (maybe). Remember the wiring is 40 years old and can be bad.

If you don't have the FSM google "280zx FSM". They are free to download from another Z car site.

Good luck, it took me 5 weeks of messing around before I got my 83 to run after I purchased it as a non-running car.
 

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Discussion Starter · #8 ·
Good luck finding one for a 82-83, they seem to be unicorns. The 82-83 can only be used in those cars. Doesn't matter if you have an auto and use a manual or if yo have a California emission and run a federal but you have to use a 82 or 83 unless you make some modifications.

I have a 83 that was a no start due to the the ECU was injecting so much fuel it was flooding the cylinders. Read about it here.

1983 flooded so bad it wont start. Fuel in oil. Checked...

I could not find a good 83 ECU, I have 2 bad ones, and converted my car to run a 79-81 ECU buy adding the dropping resistors. Car runs GREAT. You need to do your FSM Fuel Injection checks to make sure its not something else. Do all the checks. I did them 3 times to prove to myself it was the ECU. There is no way to test the ECU itself, the FSM tells you how to check the wire from the ECU to all of the things the ECU is connected to and also tells you how the check each device individually. If you eliminate all other sensors then its the ECU (maybe). Remember the wiring is 40 years old and can be bad.

If you don't have the FSM google "280zx FSM". They are free to download from another Z car site.

Good luck, it took me 5 weeks of messing around before I got my 83 to run after I purchased it as a non-running car.
Yes you are right 82-83 are extremely rare. But the thing is I am almost certain that it’s the ECU. All of the circuits wires and sensor seem to be good based on all the tests that the FSM tells you to do. I’ve done injectors (all 6), ign coil trigger input, PCM ground, and all of the other tests. And I can’t seem to find the problem that the car has with all of the wiring related to efi and starting the car. I’ve been on this thing for more than 2 months testing, wiring, among other things. So far this is the only thing I have found wrong that could be a cause for the car not starting. I have to try to see if it’s the PCM.

I have found a PCM for an ‘83. It is exactly an ‘83. The pins and model look identical. The only thing is that it’s for a 2+2 model. Does this affect anything? And if it does how can I add the drop resistors so I won’t spend so much money on an ‘83 ECU?
 

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I would only buy the ECU if it is guaranteed 100% and it came from a running car. Its a tough call saying its the ECU. I had access to a good 1981 ECU from my wife's car and a local junk yard had a 1980 car that I took the EFI wire harness out of to get the dropping resistors and the wire I needed. To add the resistor all I did was take the positive wires out of the harness along with the resistors and run one wire to the battery to power the resistors. At the end of the positive wires for the injecters I put EV1 connecors on to plug into the injectors. The negative wire for the EV1 connectors I plugged into the origional injector connector negative side then you can use any 1979-81 ECU that are cheap and EZ to find.

The 2+2 makes no matter for the ECU. Neither does the California/Federal emission or the Manual/Auto. The differance in the ECU's are just fine tunig for the application. The car will run if it a 1983 ECU.
 

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Try calling the circuit doctor in Austin, Tx. They have rebuilt multiple boards for me. Their contact is:
Circuit Board Doctors
512-215-4055.
Scott in South Carolina
 

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Discussion Starter · #11 ·
@Scott C. @kickstand80 @crayzlair @Dave M

forget the E.C.U. my datsun finally FIRED UP. It was the yellow wire from ignition switch to the starter.

Listen up, fellow Z owners especially if you're gonna install your own ignition system to start it up like an ignition board, switch or buttons. If you run your own custom positive wire from ignition switch or your ignition button make sure that the terminal from which signal is going out to the starter also has a signal going to the E.C.U. This was my problem as I ran my own wire from Battery + terminal > in-line fuse > ignition button > to starter +. But I didn't run any wiring from ignition button to ecu yellow wire. This sends a signal to the ecu that your car is starting. it should be in your harness. so run wire from switch/button to starter + AND ignition yellow wire. This made all the difference for me and saved me a few hundred dollars as I was planning to buy a new E.C.U. It was a matter of time, oh well now it's time to adjust idle and put the air flow meter back on (yes, the AFM was OFF when it fired up). Thanks for all the help, now lets continue and get this Z on it's feet.
 

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oh, so there is a non OE ign part installed? if that is the case then its very hard to diagnose. This is the MAIN reason why I like to go OE on everything, it makes the FSM a useful diagnostic reference document. I so often read about upgrade this upgrade that, upgrade is only as good as the user that installed it.
 

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oh, so there is a non OE ign part installed? if that is the case then its very hard to diagnose. This is the MAIN reason why I like to go OE on everything, it makes the FSM a useful diagnostic reference document. I so often read about upgrade this upgrade that, upgrade is only as good as the user that installed it.
I echo every word of this. As soon as you depart from stock, you're essentially on your own. And every time you work on the car, you need to take into account whether your non-stock mods have impacted the work you're doing.
 

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I concur with Dave M and pilgrim. You assumed that you did your modification properly so you went after anything and everything else. What on earth prompted you to install your starter switch and or buttons? Z man of Washington
 

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Discussion Starter · #15 ·
I concur with Dave M and pilgrim. You assumed that you did your modification properly so you went after anything and everything else. What on earth prompted you to install your starter switch and or buttons? Z man of Washington
So when I originally got the car, the guy said that he was going to send an original ignition switch along with it. For some reason it never came and I called him and he called me and it was a long process. I gave up so I wired it myself. It finally worked with a bit of time so now I just have to finish what I started. And I do that by finding out what’s keeping the car from running longer than 3 seconds. Sorry that you purists are upset or disappointed with my decisions but I guess 17 year olds ain’t have a lil somethin called p a t i e n c e .
 

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Discussion Starter · #16 ·
So when I originally got the car, the guy said that he was going to send an original ignition switch along with it. For some reason it never came and I called him and he called me and it was a long process. I gave up so I wired it myself. It finally worked with a bit of time so now I just have to finish what I started. And I do that by finding out what’s keeping the car from running longer than 3 seconds. Sorry that i didnt go OEM but I guess 17 year olds don’t have a lil sum called patience.
 

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the issue is once you have modified the car it become very hard to diagnose a problem, that's the only pure thing here. asking for help is fine but you need to understand that trying to figure out some wiring mods, esp without being right there in front of them, is very difficult. The FSM has good diagnostics and complete wiring diagrams that makes it at least possible to help, but with changes all that goes out the window. I hope you can get it working, but I will have to tap out on help since I have no idea what is going on after the mods.
 

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Discussion Starter · #18 ·
the issue is once you have modified the car it become very hard to diagnose a problem, that's the only pure thing here. asking for help is fine but you need to understand that trying to figure out some wiring mods, esp without being right there in front of them, is very difficult. The FSM has good diagnostics and complete wiring diagrams that makes it at least possible to help, but with changes all that goes out the window. I hope you can get it working, but I will have to tap out on help since I have no idea what is going on after the mods.
That’s mostly all the mods I’m going to do for now. Sorry about that ‘pure’ thing, I worded it wrong... anyhow I need to find why the car will start but won’t stay running. I’ve tried a few different things but no good. Either way thanks but I know this is going to take some time.
 

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well generally speaking if it will start and not run you need to determine if the injectors are working, if the pump is staying on after starting.

some Z cars have a micro switch in the AFM flap to run the pump when the key is in the on position. Others use the oil pressure and maybe something else, I don't know.

ZX's pretty sure do NOT use the AFM. So you need to review the wiring to the pump relay to see what triggers it on, and also listen for injectors clicking.
 

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Discussion Starter · #20 ·
well generally speaking if it will start and not run you need to determine if the injectors are working, if the pump is staying on after starting.

some Z cars have a micro switch in the AFM flap to run the pump when the key is in the on position. Others use the oil pressure and maybe something else, I don't know.

ZX's pretty sure do NOT use the AFM. So you need to review the wiring to the pump relay to see what triggers it on, and also listen for injectors clicking.
Could a Bosch noid light work as well. Or would I have to have someone else power it on for the time that it does start up?
 
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