Brake lights not working -- issue with combo switch

[jfa.series1]

Nissan did a disservice to all of the S30's by running high amperage current for the headlights/taillights and turnsignals thru the fuse block and then on to the respective switches. As the contacts in the switches became burned, resistance increased and backed up to fuse block resulting in damaged fuse contacts and melted wires. The recommendations above to use lower amperage bulbs and get all the damaged wiring repaired are spot on. And yes... you don't just want to plug in a new fuse block without cleaning up the issues.

With all that said and done, you'll still be running the primary current thru the fuse block and switches - just less of it. I strongly recommend you invest in Dave Irwin's excellent relay kits for the headlights and turnsignals. Feeding the clean power directly from the battery to the lights will make a huge improvement in lighting quality and remove these high amperage current flows from your dash area. Just my $0.02 worth - if that much!

https://www.datsun-240z-upgrades.net/

[Locke]

2 steps forward, one step back…

I spent the last few days ensuring the wiring throughout the car wasn’t corroded or broken. Everything looked alright.

The new fuse box came in yesterday, and upon installing the brake lights worked perfectly. Great! Thanks to everyone for their help with solving the issue.

Except now I have more problems—

This morning I cranked the car and left it idling while I grabbed a few tools from the shed. When I came back, it had died. I thought maybe I had let the choke back in a bit too much and tried to crank it again.

Now the car will not start, and just cranks repeatedly. I’ve done a few diagnostics to try and narrow it down, but my knowledge of the ignition system is admittedly limited.

With the key in the “On” position, I only get about 5VDC between the positive post of the coil and ground on the chassis. I’ve read that this should be 12VDC.

I also tried a test I found on another forum post. I pulled the coil to distributor wire on the distributor side and laid it on the intake manifold. I then used a small wire with one end on the positive post of the coil and tapped the other end to ground. I read that this should create spark at the end of the coil to distributor wire, but I saw none.

While turning the key to start, I tested for spark along all my wires using a timing light. Each of the wires (including from coil to distributor) made the light flash, but not at a regular interval. It seemed like it was skipping a bit.

I should probably make a new thread for this since the brake lights now work, but I wanted to check and see if it’s possible that these issues are related to the new fuse box?

If not, what are the likely culprits for such low voltage going to the coil?

Thanks again to everyone for their help. I’m happy to provide any more info I can.

Edited January 6, 2022 by Locke
added more testing info

[SteveJ]

1 hour ago, Locke said:

 

Except now I have more problems—

This morning I cranked the car and left it idling while I grabbed a few tools from the shed. When I came back, it had died. I thought maybe I had let the choke back in a bit too much and tried to crank it again.

Now the car will not start, and just cranks repeatedly. I’ve done a few diagnostics to try and narrow it down, but my knowledge of the ignition system is admittedly limited.

With the key in the “On” position, I only get about 5VDC between the positive post of the coil and ground on the chassis. I’ve read that this should be 12VDC.

No, with the key in ON, you should not see 12VDC UNLESS someone has bypassed the ballast resistor. Also, lift the negative wire off the coil to take the voltage measurement. If it's a points ignition with the gap closed or almost closed, that will affect the voltage reading unless you pull the negative coil wire.

1 hour ago, Locke said:

I also tried a test I found on another forum post. I pulled the coil to distributor wire on the distributor side and laid it on the intake manifold. I then used a small wire with one end on the positive post of the coil and tapped the other end to ground. I read that this should create spark at the end of the coil to distributor wire, but I saw none.

While turning the key to start, I tested for spark along all my wires using a timing light. Each of the wires (including from coil to distributor) made the light flash, but not at a regular interval. It seemed like it was skipping a bit.

I should probably make a new thread for this since the brake lights now work, but I wanted to check and see if it’s possible that these issues are related to the new fuse box?

If not, what are the likely culprits for such low voltage going to the coil?

Thanks again to everyone for their help. I’m happy to provide any more info I can.

What ignition system is installed? Points? Pertronix? Crane? ZX distributor with ignition module? HEI? Other? If you're unsure, post photos of your distributor with the cap off.

What is the condition of the cap and rotor? (again photos) Remove the plug wires to assess the cap. Make sure you remember the order for the plug wires, too, so you don't install them wrong.

Will the car fire with starting fluid? 

Is there gas in the float bowls?

[Locke]

Sorry for not including this earlier, I have the original points system.

When I remove the wire from the negative post on the coil, the reading on the positive post while the key is turned to ON is 12.4VDC. Putting the negative wire back on brings the reading to 5VDC again.

Here’s a couple of pictures of the cap and rotor:

To my eye, everything looks relatively sound (i.e. no burnt contacts) but you may tell me otherwise. The only thing that concerns me are the weird plastic shavings inside the connectors on top of the distributor cap.

Also, my wires looked a bit odd in my opinion:

 

I don’t have any starting fluid on hand, so I haven’t tested that yet.

When I removed the lid on both float chambers they were virtually empty with a tiny puddle of gasoline at the bottom of each:

Should they always hold gas even when the car hasn’t been cranked recently? If so this may be the cause of the issue.

I noticed that my fuel filter has a decent amount of debris at the bottom. I’ll try swapping it out and let you know if that changes anything.

[SteveJ]

So is it too far out of line to say that your car died because it ran out of gas?

If the car ran this morning, there should be gas in the float bowls. Empty float bowls means that there is no gas available to be atomized. Try putting about an ounce of gas in each bowl. Shoot some starting fluid down the throat of each carburetor. (Tip: Have the air cleaner off and raise the piston in the carb to shoot the starting fluid into the intake.)

If you have gas in the tank, then why is it not getting to the carburetors? Fuel pump? Fuel filter? Rotten hoses? Rust clogging the system?

[SteveJ]

I left out stuck valve at the float bowl.

[Locke]

Fuel delivery was the issue. Replacing the filter fixed it for a while, but it’s back to having trouble starting.

I’m guessing more gunk from the gas tank made it throughout the fuel lines and is choking it out, so I’m having a shop clean out the tank and clear the lines.

That being said, it looks like all electrical issues are resolved. I’m very grateful to everyone for their comments and helping me fix the issues!