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Discussion Starter · #1 ·
Hi, I can't set the time in my 1981 280zx digital clock. I was wondering if this is a known issue or if there are any fixes or if I'm just doing it wrong. I press the top button and the time starts blinking, turn the bottom knob to set the time, then I press the top button again and the clock goes back to 12:00. Any help appreciated

also having trouble to find a fuel pump relay or fuse
 

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You can set the clock 2 times a day. Noon and midnight! Mine does the exact same thing. 40+ year old electronics........I know a old school repair guy but you have to remove the dash to get the clock out!

More info needed on the "trouble finding fuel pump relay or fuse" What is the issue and please use complete sentences. Are you trying to find the location of the relay/fuse in the car or are you looking to purchase a new relay to replace your old relay?
 

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Discussion Starter · #3 ·
All right, thanks for helping clear up the clock problem. Sorry I wasn't clear about the fuel pump relay. My car's engine is out right now but I want to be able to power it on for testing the electronics without burning out the fuel pump and flooding my driveway with old gas. I just want to find a relay or fuse I can unplug to stop the fuel pump
 

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Here is a fuel pump electrical diagram
Schematic Font Parallel Engineering Rectangle


Here is how it works
The electric fuel pump has 3 switches. The first is the ignition switch. The second is a normally open contact on a relay. That relay coil is energized when the alternator is turning fast enough. (Note the voltage for that coil comes from the yellow wire between the alternator and voltage regulator. If you swap to an internally regulated alternator, you will remove the coil voltage from this circuit, and the fuel pump will never get voltage.) The last Diagnostics go like this:
  1. Turn the key to the ON position.
  2. Use a voltmeter or test light to verify you have voltage (to ground) on the black/white wire on Relay 1. (It's the 4 pin connector.) If this test fails, find the break in the wire.
  3. Start the car.
  4. Use a voltmeter or test light to verify you have voltage (to ground) on the green/white wire on Relay 1. If this test fails, you need to replace Relay 1. (This will require substituting a modern relay.)
  5. Use a voltmeter or test light to verify you have voltage (to ground) on the green/white wire on Relay 2. (It's the 6 pin connector.) If this test fails, find the break in the wire.
  6. Use a voltmeter or test light to verify you have voltage (to ground) on the black/white wire on Relay 2. If this test fails, you need to replace Relay 2. (This will require substituting a modern relay.)

Looking at 1980 FSM under the Engine Fuel chapter on page 21 you'll see the schematic of the fuel injection system. You can see that when you turn the key to Start that B on your ignition switch is tied to the +12V on the battery and power is shorted to Ignition and Start outputs on that switch. Power then goes through the starter relay from the Ignition side through the coil on the "L" side of the alternator to ground (when the engine isn't running). (It also goes through the Start portion of the relay circuit and activates the other Fuel Pump relay). That coil pulls in the relay for the circuit that goes through the oil pressure switch (when the engine isn't running) to ground. That pulls in the second set of contacts that activates the other Fuel Pump relay and sends a signal to the ECU.

It looks like the secondary relay is to cut fuel if the oil pressure switch opens which it shouldn't do when the engine is running. Safety switch if you loose oil pressure.

So to make a short story long it looks like the fuel pump should run forever if you have the key in the start position whereas other S130s have a fuel pump controler that just runs the pump for a few seconds in the start position.

Relay locations
Wheel Tire Vehicle Motor vehicle Car


White Font Art Parallel Illustration
 

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Discussion Starter · #5 ·
Thanks that helps a lot! It's really cool that the fuel pump is cut off when you lose oil pressure too, I didn't know that was a feature on these. Thank you for the help
 
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