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Discussion Starter · #1 ·
Hey all

I have not been here in a while and I see there are some guru's lurking these posts... so here is my problem. ( 5 years old now )

1980 280zx, n/a 160,000 miles. owned for 8 years.

After driving for a random amount of time, anywhere from 5 min to 3 hours, when I go to turn off car it would over-run or diesel. like it was carboned up. , it could be on a cool day or a warm day. also it does not happen all the time, once out of every 3 drives. Also, after it did it, it would take a little longer to start, 5 to 10 turn overs, normal is 1 or 2 turn overs to purr up ( which it would do every other time ). I would try it and it would turn over 5 or 6 times, I would turn it off, let the starter wind down then try again and it would start after 2 or 3 engine turn overs and then run fine. I could then shut if off right away and it would not over-run. When running and idling the car runs perfect, no sputs, spurs, spits, surging or roughness, just smooth sailling.

Here is what I have done over the years.

- 6 new ( Nissan ) fuel injectors.
- all new fuel rail lines / hoses in the engine bay. ( had them chrome plated, but it did it before that mod ) - looks great now.
- New fuel pressure regulator ( not used , brand new from Nissan )
- Fuel line pressure check - within spec ( was a while ago though )
- New AFM boot from afm to intake.
- New Cold Start Valve.
- New thermostat
- Disconnection and re-connection of most engine external components and hoses, all hoses tight and not cracked.

I am not sure what else to check, some sensor somewhere?

Recent problem - no starting - no noise from fuel pump, was it my problem the whole time - I dunno. I need ideas even if it is not the fuel pump.

The only other thing I have not really looked at is taking the head off and checking the cylinders and valves for build up.

I use Castrol Synthetic oil, K&N filter. I have tried good run on the highway at over 3500 rpm for 8 hours, that night after I got home it dieseled again.

The car has great power and sounds great, I am at a lossssssssssssssssss.

Ryan
 

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oops... check this!

Checked the Z bible (aka: the factory service manual, I you don't have one... get one. All Z owners should have one) In the troubleshooting chart the thing to check for run-on/dieseling is the cold start injector. You stated that you replaced it... perform the tests in the service manual, check the thermotime too and wiring too.
 

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Discussion Starter · #4 ·
Re: oops... check this!

Yah, I got the service manual.

It did it before and after I replaced the Cold start Valve ( it blew a seal one day and shot gas 6 feet in the air from the engine bay when I opened the hood ).

I have not checked the thermotime yet. I am going to go through all the wiring and testing of all my sensors in the next month, once I get it running again ( no fuel at the moment ).

thanks

Ryan
 

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Discussion Starter · #5 ·
Timing - is good, had it checked and re-checked several times ( I do not have my own timing light yet , waiting till after my birthday as it is on my list, heehehehe )
 
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