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1980 Z loses power quickly between 2-4K RPM

Old 07-10-2018, 07:29 PM
  #1  
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1980 Z loses power quickly between 2-4K RPM

Fuel injected 1980 280ZX
147k Miles
reving engine in neutral- power quickly drops at 4K.
in gear it barely hits 2k. Engine loses power and sputters. Will die if I dont let it go to idle.
fuel pedal is held in same spot.
replaced- fuel filter and fuel lines to filter
spark plugs
air filter
ignition control unit
cleaned idle control valve plug contacts, AIR meter, ICI.
cleaned fuel tank screen.
reamed out catalytic converter- it’s now hollow.
i imagine I have a fuel pump issue. I have a test kit. Not sure how to test for volume though
any ideas on what to check would be greatly appreciated! I have to get this car running ASAP.
☮️
video link -

Last edited by Hotrod460; 07-13-2018 at 09:46 AM.
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Old 07-12-2018, 10:55 AM
  #2  
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Welcome to ZDriver!
To clarify... did this just start out of the blue? Car been sitting for a long time? Fresh gas?
An easy way to know what's going on is to pull & read the spark plug tips. Black? White? Soot? Wet? Dry? etc
Checked timing? Checked cap, rotor, coil?
Checked Cylinder Head Temp Sensor (between spark plug 5 &6) or Coolant Temp Sensor in thermostat housing (if yours is pre P79 head)?
Check fuel pressure by installing a T in the fuel line after the fuel filter & before fuel rail. Running should be 30-35psi, should hold pressure when off.
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Old 07-13-2018, 09:46 AM
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Thank you!
The Z had sat for several years. I emptied the tank and cleaned the screen. Fresh fuel in it now. It was running pretty good. I have worked out several other run ability issues.
This one is more difficult for me.
I'll pull the plugs today. Timing, cap rotor all good. Coil is working. Not sure how to verify if it has issues or not.
N47 Head
Does the cylinder head temp sensor and Coolant sensor regulate fuel? How do I test them?
I'll put a T in line today and get a reading.
Really appreciate your help NismoPick !!

The video shows me reving the engine a few times. Then I hold the pedal steady and tach falls.

Peace
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Old 07-15-2018, 09:02 PM
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A fuel pressure test would be really helpful... also, try removing the vacuum line to the fuel pressure regulator... it might have ruptured and if so, is dumping fuel into the intake manifold. That's a common problem with Z's that have sat for a long time.
N47 head doesn't have a CHTS, just a coolant temp sensor in the thermostat housing. It's the main temp sensor telling the ecu how rich / lean to make the AFR. When it's disconnected or toast, it usually defaults to pig rich.
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