# 1985 Nissan 720 4x4 King Cab Idling Problems



## Tylinater (Oct 23, 2016)

I currently own a 1985 Nissan 720 4x4 King Cab with the Z24 engine on it. The Idling and Stalling problems began a couple of years ago. So here's what I have done so far in trying to fix the issue

1. New Water Pump

2. New Fuel Lines cause they ripped

3. New Distributor Cap and Rotor

4. New Spark Plugs

5. New PCV Valve

6. Did the smoke test and the only places where smoke comes out is the bpt valve, the weep holes on the vacuum switches and out the top of the carburetor.

7. New Radiator Cap

8. New Anti-Dieseling Solenoid

9. Fixed 2 electrical shorts thanks to the multi meter measuring on the fuse box

10. Replaced a corroded terminal on the ecc main relay and at the same time got the anti-dieseling solenoid and the rest of the engine to receive battery voltage.

11. Manually testing the EGR and BPT valves and they both work fine.

12. Found out that the oil pressure sending unit for some reason became unplugged so plugged that back in

And after ALL THAT, the problem still occurs. However recently, I've been doing some tests and here's what happened.

1. Plugged the vacuum hoses to both the tvv valve and the vacuum control valve and problem doesn't go away

2. Hooked a vacuum gauge to one of the hoses and it reads steadily around 5-8 inhg at idle.

3. Hooked it up to one of the hoses that goes to the manifold and reads the same thing. It should read around 17-22 Inhg. 

4. Turns out that the vacuum switch that is connected to the exhaust plugs was bad, took that off so now on the vacuum gauge it steadily reads around 15 inhg and revving the engine it goes up to 18 inhg and back down to 15 inhg. Something else is wrong with it.

5. Replaced both fuel filters and it did not fix it.

6. Replaced all of the plug wires with a brand new set that fit.

7. Sprayed carb cleaner around the base of the carb and the idle rpm's went up and after that, the engine kept doing it meaning that the engine is surging and not idling steadily.

8. Did timing light on all of the spark plugs. All of them have consistent timing.

9. Disconnected and plugged all the lines that go to all of the emissions control components and no effect. 

I am just about ready to give up on this thing. Any ideas on what else could it be?


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## ommynous (Aug 23, 2016)

I'm only saying this because it wasn't listed, but a compression test?

Also, bumping for interest in whatever your problem is.


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## smj999smj (Jan 1, 2006)

You say you sprayed carb cleaner around the base of the carb and the engine revved. That would be an indication of a vacuum leak at the carb base gasket. You should also check around the intake manifold gasket and check the mixture adjustment of the carb.


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