Ok I have a 83 NA that had a bad ECU, I found a replacement. Before I replaced the ECU I had no fuel pump at all. Open the ecu and found it was burnt.

Now with a new ecu it starts, runs for about 3 or 4 seconds and dies. It sounds great when it is running, no missing out or any funny stuff. But it just dies.

If you try to start right away it won't but if you wait 2 or 3 mins it will and than dies again. It is very consistent. I can repeat the same thing every time. So what ever is wrong it's not a flaky problem.

I have a FSM and have done all the test they list but so far have found everything to be fine. I know the fuel pressure is up. I added 10 gals of fresh gas.

Does anyone have any ideas. I just bought this car and have never seen it run. The ECU was bad when I got it. it's almost perfect with only 65K miles on it.

Thanks

Chris

 

Does it have proper spark? Does it have proper fuel delivery?

 

Let me add a few more thing I know.

I pulled the AFM and just for the fun of it tried to start it. The car did the same thing it did with it installed. So I'm guessing the AFM has nothing to do with my problems or maybe that's a sign it is the AFM.

Also The ECU I have is for a 1982 not a 1983, I have no way to test it was good in the first place I'm assuming it was the guy I got it from is here on zdriver, but maybe he doesn't know if it was a good one???



Each time the key is turned on the pump runs for a few seconds as it should after taking a fuel bath I now know the pressure is there but need to test it to see how much.

I plan to put a gas pressure gauge inline on it over the weekend and watch to see if the pressure is held constant. At least I'd know that for sure.

I will also put a timing light on it to see if the spark is cutting off.

But I'd guess that the problem is related to the fuel injectors stopping. Not 100% sure how to test that just yet, maybe with may audio test set, that's a set of head phones connected to a amp that has a probe on it.

The only problem with some of these test is it won't tell me why the fuel pump, spark or injectors shut off. i mean let's say I find the fuel pump shuts off right after I start the car. If all the relays & wires are good it still leads back to the ECU. Same for spark and injectors.

Just some thoughts, I'm really hoping someone who has had this very same problem answer this.

Oh yea, anyone use a ECU from a 82 on a 83?

 

NismoPick

I just up dated my OP with some more info.

I know when it starts is runs and sounds great, but for only 3 or 4 seconds. So from that I know the spark is good enough, but not sure if it's being cut off by the ECU.

Same with the fuel pressure.

 

I am willing to bet, your AFM is toast. If your car didn't change when you unplugged it. The electronics inside it are shot. I have been puzzled before with my Z only running a bit then dying. And it turned out to be my AFM. Replace it, and I bet your Z will run like a top.

 

i just tested AFM to the FSM specs and it test good, I don't think there's any electronics in the AFM just resistors????

 

Okay, how about your CHTS? See if that is bad, contacts corroded, or not plugged in good enough. Try that, and I will try and think what else it could be. Good luck.

 

Ok what's a CHTS ...thinking?????

 

Nevermind I found it.

Acronym, Definition. CHTS, Cylinder Head Temperature Sensor (Nissan).

I'll check it in the morning.

 

you say you know you have fuel pressure. how do you know that without a fuel presure gage in the system? sounds more like the fuel relay is cutting fuel pump off after the initial run when you turn key to ignition. Hot wire the pump and see if it runs. or install pressure gage to see what is going on.

 

I know there's still pressure there because I took a gas bath when I tried to take the fuel line off. But not sure how much, I'm going to the shop now and will test it with a gauge.

Thanks

 

I have tested the CHTS, or coolant temp sensor and it appears to be bad. One side is grounded and the I get 50 ohms between pins.

The leg that is grounded is not the one that gets grounded through the plug. Also given the temp chart in the FSM it should be reading close to 2K ohms across it.

I'm looking for a temp sensor now, I'll post the results later.

 

I thought that the 83 ecu was only good for the 83 Zx , because it has a label saying to only be used in an 83..Could that be the problem the 82 ecu not being calibrated to work on an 83..

 

I was using a 1979 FSM when trouble shooting my 1983. Don't do that if you are looking for info in the CHTS and Temp sensors. They are very different.

In the 79 manual they don't even mention a CHTS just the coolant sensor and the therotime switch. I was only using the 79 manual out in the shop because it's the only book I have in print. The 83 book is a PDF.

Turns out all the sensors including the CHTS test out to the FSM specs. Plus considering the fact the car does start and run perfect for at least 4 or 5 seconds I'm left to believe the ECU is either bad or a 1982 will not work in a 1983.

So I'm looking for a 1983 ECU. Any body have one???

 

Good to hear. I have been in your situation before. So things stick in my head, that could be wrong. Basically the AFM, and CHTS, are one of the major do or die components. That is if they fail or are not working correctly. The car will either run horrible, or not run at all. Keep us posted man. Hopefully a new sensor will fix the problem.

 

Ahh, never mind my previous post. Looks like you beat me to it. Hope you get it figured out man.

 

Is your '83 a digital or an analog? If it is analog, you can use the '82 ECU. If it is digital, it could cause some problems.

 

It's analog but I'm convinced the ECU I have is the problem. There just isn't anything left it can be.

My old ECU was A11-652-805 and the one I have now is A11-620-800 ( i think).

Been looking for someone to post who has exp using these two ECU's in exchange for one another. So far all I've seen is ppl saying it should work but that's not the same as it will work. if there was a A11-652-805 on ebay right now I'd buy it...lol

 

Yeah you could have a faulty ECU. I am sure the '82-'83 ECU's are pretty much the same. If they are both analog. I have a digital dash '83, and I know there are some differences. Anyway yeah I need my ECU's for my '82's. I only have 2, for 2 '82's. lol I do have an '81 5 speed. But I think that is quite different from '82 and '83.

 

No one has said this yet so try this. unhook the L plug from the back of your alternator, and turn your key to on, the fuel pump should stay running any time the key is in on or start, then try to start your Z then.

If it starts and stays running then you could have a bad circuit in your fuel pump electronics.

 

Thought I'd review everything in one post.

Ok here's where things stand with this car. It's a 1983 NA 5spd Analog dash with only 65K miles on it. it's almost in show condition. The prior owner said one day it wouldn't start anymore. They did nothing to try and fix it just parked it for 2 years. yes I put fresh gas in it.

When I got it the fuel pump would not turn on and after chasing that down we found the ECU was burnt, even a transistor had cracked in half.

The ECU I had was A11-652-805 and the one I replaced it with was from a 82 and had a A11-639-800 on it.

We bought it ECU from a respected guy here on zdriver, he said it was removed from a great running car.


The problem we have now, It starts and runs for 3 or 4 seconds and dies. It will do this 2 or 3 times in a row but will stop starting after that unless it sits for 5 mins. Than it will repeat.

It's been doing this for a few days with not change in symptoms so I know it's not a flaky type problem.

Here's a list of test we have done using the FSM.

AFM --ok
CHTS--OK
Therotime switch--ok
Fuel pressure while starting --ok 30+PSI and never drops.
Spark is good and never drops off.
Battery voltage is good.

We know from using either it will fire anytime it has something to burn, so are 100% sure it is a lack of fuel IE injectors not firing, or they are all plugged up??

We listened to the injectors with a trouble shooting headset and can not here them click.

We checked the voltage on the injector connector and there's 12 volts there as it should have so pretty sure the EFI relay is good and on.

I ran out of time today, but plan to do the light bulb test in the injector connector tomorrow. I tried testing the voltage on the connector with my digital voltmeter but the reaction time of the meter is to slow to be accurate.

Have we missed anything?

Hey another note to end this with. The old owner did take the fuel line off between the filter and the engine and left if off for the 2 years it sat outside, just wondering if it's possible bugs crawled up the open hose, spiders or ants? there didn'y seem to be anything in there when I got it?? or maybe since the injectors were allowed to dry out if they are stuck? anybody use a injector after it sat around for a long time, will they stick?

 

If it runs for a bit that means its getting fuel and the injectors are working fine. it just sounds like the fuel system is shutting off after the engine starts. The fuel pump will ALWAYS pump at START but if it doesn't detect anything running IE OIL PRESSURE OR ALT OUTPUT it turns the pump off after 3-5 seconds. If both of those connectors are off the car will do exactly what its doing now, if one is off the fuel pump should run if the key is in ON or START, If both the alt and oil pressure sender are bad the test I said to do will make the car act the same way.

If that doesn't make a change pull the fuel pump relay out and jumper the key on power right to the fuel pump in the block. if your car runs then then you only have 3 minor items to check.

 

I have put a pressure gauge inline and the pressure never drops below 30PSI. So not sure it's related to the pump shutting off.

 

The test we ran today confirmed that the injectors are not firing. Did the light bulb test and it did not light. I have 12 volts going to the injector but they are not being supplied a ground by the ECU.

My best guess right now is the ECU is either bad or not compatible with my 83.

I'm also thinking that I might have a very small amount of leakage from a few injectors and that's why is starts at all, it's either that of they are firing once in awhile giving enough gas to start for a few seconds. ???????

I might for fun put a 9 volt battery on one injector tomorrow and see if the injector fires and reduces the pressure in the gas line.

Anyone have a ECU for a 1983 na 5 spd???

 

I am having the same issue with my 83 N/A. What I think is happening, during the few seconds it runs; it is a squirt of fuel from your cold start injector that is enabling it to run breifly. Try this just to make sure the injectors are functioning. Remove your ECU plug, take a jumper wire, ground one end to the body, and briefly short out terminals 2 thru 7 on your plug. You should hear your primary injectors "click". If they are seized shut the click will be soft then get louder with every time you ground each terminal. You can also install your pressure gauge and use this method to energize the injectors, rather than the 9 volt battery option.