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1985 Nissan 720 4x4 King Cab Improper Idling and Stalling


Tylinater

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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. BTW Here's a pic of what the engine looks like (Not mines personally but you get the gist).

datty72006.jpg

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.

I don't know what's going on here. I don't know how many people on here have experience with working on cars but I need help and I don't wanna spend a lot of money and my time working with this thing.

PS: My dad got it in late 1985, rebuilt the top end of the engine little over 20 years ago before I was born and at that point it had 190,000 miles on it. Now it has little over 243,000 miles on it.

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  • 2 weeks later...

Update:

1. 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.

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

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

4. 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.

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

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

Any help would be appreciated.

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  • 2 weeks later...
34 minutes ago, Taurus Racer 13 said:

A simple vacuum leak will cause a  rough idle and cause stalling Replace all the vacuum lines

I did the smoke test at all of the vacuum lines and no smoke came out. That's means that there is no leak. However i noticed that the timing is bouncing around and it shouldn't do that. Also the idle rpm's continue to go up and down so I think it might be a computer controlled problem at the carb or ECC.

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