Ignition help needed on '78 280z

[Zed Head]

19 hours ago, jrod81 said:

2] With ignition switch in "ON"  tested voltage at ignition coil and got =12.3V

No need to run a jumper wire to the coil if you already have this.  As SteveJ said, just make sure you also have it at Start.  Stand your meter up where you can see it or have somebody turn the key for you.

Not sure that you're thinking through the things that happen when you turn the key.  

12.3 isn't a very well-charged battery.  If you have a charger you might top it off.

[jrod81]

On 2/28/2018 at 4:53 AM, SteveJ said:

You are close. All 5 (6?) should have constant power.

Ok, i do not have constant power on all 5. Based on the schematic the WR come from the starter solenoid HOT. I will start my troubleshooting there. Also check the voltage levels on ignition when in the "RUN" position to rule out the ignition switch.  Will report back soon when the rain stops

[SteveJ]

Based upon the diagram I posted, can you indicate where you didn't have 12 VDC?

[jrod81]

3 hours ago, SteveJ said:

Based upon the diagram I posted, can you indicate where you didn't have 12 VDC?

1 - i have constant power, 2 - i only have power when switch is on

[SteveJ]

Are you measuring voltage to ground at each link? All of the white wires are connected together. Therefore if one has voltage, they ALL should have voltage. If you didn't have voltage on #2 at the white/red wire until after you turned on the car, that means that the fusible link is bad, and something is backfeeding the circuit.

 

Edit: By the way #2 is the link to the fuel pump power.

Edited March 2, 2018 by SteveJ

[jrod81]

9 hours ago, SteveJ said:

Are you measuring voltage to ground at each link? All of the white wires are connected together. Therefore if one has voltage, they ALL should have voltage. If you didn't have voltage on #2 at the white/red wire until after you turned on the car, that means that the fusible link is bad, and something is backfeeding the circuit.

 

Edit: By the way #2 is the link to the fuel pump power.

Ok thanks for the advice. I remeasured testing only the white wires with good ground and they are all HOT with 12v. I also verified the fusible links were good by checking the voltage on one of the end connectors with the other end plugged into white connection side.

I have traced 12V on the WR wires all the way back to the cabin.  So now i at least can narrow my troubleshooting to inside the cabin. Everything from the ignition switch down to the relay.  I have a strong suspicion that the issue could be the ignition relay. I'm guessing it is a normally open switch and when voltage is applied it closes that is why it works when i jump the fuse box. It is energized some how and closes the switch. Does anyone have a good schematic of how the ignition relay works? is it single pole single throw?

[jrod81]

On 3/2/2018 at 1:16 PM, jrod81 said:

Ok thanks for the advice. I remeasured testing only the white wires with good ground and they are all HOT with 12v. I also verified the fusible links were good by checking the voltage on one of the end connectors with the other end plugged into white connection side.

I have traced 12V on the WR wires all the way back to the cabin.  So now i at least can narrow my troubleshooting to inside the cabin. Everything from the ignition switch down to the relay.  I have a strong suspicion that the issue could be the ignition relay. I'm guessing it is a normally open switch and when voltage is applied it closes that is why it works when i jump the fuse box. It is energized some how and closes the switch. Does anyone have a good schematic of how the ignition relay works? is it single pole single throw?

I checked the connections to the ignition switch relay and found that there was 12v at the WR connections; however, there is no power from the Black and White wire that appears to be coming from the ignition switch. I get nothing when turning ignition to "RUN" either. Question if this is supposed to be constant hot, or hot only when ignition switch is  "RUN". I currently am getting neither.

[Zed Head]

Are you trying to get everything back to the way it should be or just get the engine started again?  You said that you ran it with the fuse box jumpered for a while.

You might just reset your thread with a description of what you're trying to achieve, right now, and what the status of things are , like the coil power, and whether you've checked for spark, or tried to start it with fluid.  It might be that you actually have an ignition module or distributor problem, and the jumper wire to the fuse box didn't really do anything.  It was just a coincidence.  A red herring, as they say, or maybe a red herring that swam away.

 

One sequence of troubleshooting that many of use use is -

Turn the key to start.  Engine turns over. 

Turn engine over, check for spark. 

Getting spark, check for fuel.  Check for injection.  

Unsure on fuel or injection, try starting fluid.  It should start for a short burst because there is spark.

If it starts, then dies, with starting fluid, then troubleshoot injection system.

 

This is a good sequence because those things are in the order that the EFI system would use them.  We already know that the engine turns over, and you have power at the coil.  Time to do the next step. Spark.

[yellow zee]

Old thread i know... wondering if this ever got resolved and if so how ?

[Zed Head]

jrod hasn't been back since 3/31/2018.

[SteveJ]

2 hours ago, yellow zee said:

Old thread i know... wondering if this ever got resolved and if so how ?

If you have a similar issue, you may just want to create a new thread.