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Starts, idles then dies

Old 05-07-2017, 12:25 AM
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Starts, idles then dies

Good day, I just became the owner of a 1985 300zx t-top (sorry if i don't call it properly, is this the 2+2?)
a week ago. I thought i got a deal but now I'm concerned. I did look at some other threads and tried to trouble shoot but to be honest I'm not understanding some of the steps. I'm mechanically inclined on the basic level so no I don't know much.
I do apologise if I do anything irritating for you veterans.

So now to the car,
I never got to get it running to take for a drive yet so I'm a little ansy.
After tossing in a new batt I attempted to start the z. Fired right up idled approx 5-10 seconds then sputtered and died. Wouldn't kick back over unless it sat for about 5 min then would do it again, upto 10 sec idle, sputter and die. If I try cranking right away it jus cranks. Let sit 5 min and would turn over but die.
I assumed fuel filter was the issue after taking it off and seeing the chunky debris coming out. So after the new filter I tried again but it was the same.
So not sure if the fuel pump is not working properly I opened up the fuel sending unit access in the back and turned the key on to see if the pump turn on, the pump stays running constantly unless the key is off. Not knowing much about this I spent time looking through different sites and forums. I'm not sure if i did it correctly but I attempted to check a few connections, grounds and a few inline fuses that I read in a different thread but couldn't find anything out of the norm.
Next I checked fuel pressure regulator since it is making a hissing noise with the key on and also checked the fuel rails if I did this correctly it all appears to be good. It has proper flow and pressure going into the injectors
There is a bit of an electrical issue with the car, I found a bad cracked wire in the little box next to the battery (couldnt find the name of said box, but it has 4 connectors that are looped to themselves) would send a pic but the car is at my cousins house a city over. I redid the broken wire with new wire andconnectors then the blinkers, interior minus the cluster lights that were not working previously came on.
At this point I'm feeling a little lost. Not sure what angle to look at or where to focus next. I've seen terms that I didn't understand and can't seem to locate them through manuals or pictures online.

I apologise if this isn't proper info asking for help
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Old 05-07-2017, 12:49 PM
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One suggestion, worth a check: There are two solenoids on your air regulator (right of the engine, high up) the idle-up solenoid and the fast-idle control. Both solenoids have to work right for the engine to idle right. You can remove the solenoids one at a time and check their operation with a charge from the battery. They audibly click open/closed if working. I had to replace both on my '86 na when it would not idle, had to buy a whole air regulator from a recycler, $35 if I remember. SO check those solenoids for correct operation.

WELCOME to ZDriver!

Last edited by zxguy1986; 05-07-2017 at 12:57 PM.
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Old 05-08-2017, 03:41 PM
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Well...
Im at a pause in the getting it to start for the time being. Found some bad wires, connections and fuse links and when replacing a fuse the tcm started smoking, fried one transistor and the ecm got heat damage across afew paths on the board.

Looking into the harness found some (sorry if i offend) tweaker patches. Mainly between the ecm and tcm harness. I knew i was buying a project but I'm a little worried that it might turn into as over budget project.

I bought it for $400, req ous back around $160. Interior is shot but the body is straight and solid.
I was looking to budget the project between $1500-$2000, in your opinion do you think its worth continuing?
Or should i count it a lost
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Old 05-08-2017, 06:24 PM
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The Z31 is a magnificent machine. When all the parts are finally back to performing the way they were designed and built to perform, the Z31s are incredible vehicles. They can and will run forever. The Japanese really hit the jackpot with them, just because they kept looking for an even better "sports car" than they had made with their previous Z models. In my mind, they did that in spades. My Z31s are miracles, a beautifully 'heavy' but smooth ride, as much power as you will need, great gadgets, interior comfort, amazing reliability, year after year, with just basic monthly maintenance.

You have a way to go before you get to that point, but there is nothing like a Z31. Your call now. Abandon it for something easier, or keep on with it. I wish everyone could know the Z31 I know. Unique, almost a miracle! I say, don't quit. Guys are here to give you whatever help you need. Take that Z to 100% like-new performance and at least know the miracle. You will know what we Z31 guys know!

Last edited by zxguy1986; 05-08-2017 at 06:28 PM.
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Old 05-11-2017, 05:42 PM
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Looks like new harnesses. Ecm/ecu (not sure which considered) tcm, relays.... pretty much a rewire.
Been a looong time since i had to redo electrical on a car but not the first time so i have a good idea on it. Only bad thing is the interior is sooo old an brittle its gonna need to be redone now. Guess I'll be on this car for a bit.
If it wasn't for it being a z I'd roll it away.

I've had a few 260s and a280 before this z and thought it would be awesome to get back into one.
Oh yea was able to convince the wife to up the budget and let me light weight overhaul the whole car
Sooo now I got my project car that i get to build the way I prefer.
I'll be hitting this forum from time to time to show progress
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