Electrical Gremlins - Lights & Switches?

[64nailhead]

What's the best way to test that ground?

Thanks.
John

I’ll get back to you when I’m not working later tonight.

 

[JohnIL]

The light socket can cause this. Is the fuel
Pump still turning on with the headlights?

I don't think so, but I'll have to try it again tonight to verify.

 

[64nailhead]

If the pump isn't running with the lights on, then that implies that the socket repair resolved the issue. But it identifies some crappy ground paths. You mentioned that you had the fuel pump grounded to the body and I'll assume your light was grounded there as well. That would tell me that your ground from the body to the battery is not good enough.


I have a grounding system on all of my home built stuff that is employed by many others, and it has never let me down. But my stuff all has the battery in the trunk and the fuel pumps are back there as well. I can describe ifyou want. But I'm more interested in if your repair resolved your fuel pump issue and a pic or two of you pump ground.

 

[JohnIL]

If the pump isn't running with the lights on, then that implies that the socket repair resolved the issue. But it identifies some crappy ground paths. You mentioned that you had the fuel pump grounded to the body and I'll assume your light was grounded there as well. That would tell me that your ground from the body to the battery is not good enough.


I have a grounding system on all of my home built stuff that is employed by many others, and it has never let me down. But my stuff all has the battery in the trunk and the fuel pumps are back there as well. I can describe ifyou want. But I'm more interested in if your repair resolved your fuel pump issue and a pic or two of you pump ground.

I would be interested in hearing/seeing your grounding recipe. It might give me some ideas on how to improve my grounding situation at the rear of the car.

I can confirm that the new light socket fixed the problem. I even put the old flasher back in and it works. It's weak, but it works. It got tossed and I put the new one back in. I'll try to post some pictures of the current grounds later tonight. Thanks.

 

[JohnIL]

I have seen the enemy and he is me...

64nailhead,
I think you were right about the cause of the sketchy fuel pump ground. The day that I wired installed the gas tank, I must have been in a hurry. I grounded the fuel pump and the fuel sending unit to factory grounding screw. I didn't stop to think about the fact that we painted over the grounding point with chassis paint when we did the underbody rust repair. So, I drilled a fresh hole, sanded away the paint around the hole and used a shiny new self-tapping screw. I don't know if it will help anything, but it sure couldn't hurt! I've attached some pictures of the wiring busses next to the battery, the body ground cable to the front fender, and the fuel pump ground before and after.

If you have a minute, I really would like to see your grounding solution. I'm always looking for a better way. Thanks.

John

 

[64nailhead]

Yup, that fuel pump ground is sketchy. The self tapping screw through the frame is ok. But though a piece of thin sheet metal is a recipe for a future issue imo.

I use a main grounding point - the block. Not the heads , but rather the block. Your ground buss bar is a great idea. Basically, use a main grounding point. Battery should be grounded to that. Then every major component is hooked to the main grounding point. Your ecu should be grounded to the main point. In my setups, I have a ground from the body to the block and from the frame to the block. I install two additional in our G-bodies - one from core support to the frame, and one from the rear body to the frame. My battery has the ECU ground, the fuel pump grounds, and a #2 wire that runs to the block.

I’ve read that it is possible that you can have too many grounds because it can cause a ground loop that is an easier path (less resistive path) to the battery than a main ground. I’m not able to get a full understanding and give a solid description of that. But a couple of body grounds, a couple of frame grounds and a very very good engine ground will always work.

If I were you, I’d move the fuel pump ground to a cleaned and solid mount to the frame, block or ground buss bar - loose the zip screw. Most zip screws are very course thread - that screw in thin metal is a recipe to be loose before long. Or you could put a nut and bolt through the frame or body, then double nut the pump ground on it so you can apply 15-20 ft/lbs of torque to the doubled nut.

 

[JohnIL]

Yup, that fuel pump ground is sketchy. The self tapping screw through the frame is ok. But though a piece of thin sheet metal is a recipe for a future issue imo.

I use a main grounding point - the block. Not the heads , but rather the block. Your ground buss bar is a great idea. Basically, use a main grounding point. Battery should be grounded to that. Then every major component is hooked to the main grounding point. Your ecu should be grounded to the main point. In my setups, I have a ground from the body to the block and from the frame to the block. I install two additional in our G-bodies - one from core support to the frame, and one from the rear body to the frame. My battery has the ECU ground, the fuel pump grounds, and a #2 wire that runs to the block.

I’ve read that it is possible that you can have too many grounds because it can cause a ground loop that is an easier path (less resistive path) to the battery than a main ground. I’m not able to get a full understanding and give a solid description of that. But a couple of body grounds, a couple of frame grounds and a very very good engine ground will always work.

If I were you, I’d move the fuel pump ground to a cleaned and solid mount to the frame, block or ground buss bar - loose the zip screw. Most zip screws are very course thread - that screw in thin metal is a recipe to be loose before long. Or you could put a nut and bolt through the frame or body, then double nut the pump ground on it so you can apply 15-20 ft/lbs of torque to the doubled nut.

Thanks for the advice. I'll look for good spot on the frame to ground the fuel pump.

John

 

[Dayzedandkonfuzed]

This is all good info, however I would also be checking the grounds in the dash. There are at least 2, one on either end on the bottom. It kinda sounds to me like the headlight switch does not have a good ground. I had a similar issue except my wipers would turn on with the headlights, and only one headlight would light up. I'm pretty sure it was accompanied by the same turn signal issue you have, with the left working fine but the right lighting up solid. I had the dash out and missed the ground on the rh side of the dash. Basically the headlight was finding a ground through a different circuit. After sitting that long, could have lost a ground or two.

My motto is, if its strange as ****, it's probably a ground.

Truthfully, I just wanted to post to compliment your avatar pic.

 

[JohnIL]

This is all good info, however I would also be checking the grounds in the dash. There are at least 2, one on either end on the bottom. It kinda sounds to me like the headlight switch does not have a good ground. I had a similar issue except my wipers would turn on with the headlights, and only one headlight would light up. I'm pretty sure it was accompanied by the same turn signal issue you have, with the left working fine but the right lighting up solid. I had the dash out and missed the ground on the rh side of the dash. Basically the headlight was finding a ground through a different circuit. After sitting that long, could have lost a ground or two.

My motto is, if its strange as ****, it's probably a ground.

Truthfully, I just wanted to post to compliment your avatar pic.

Thanks, for the advice and the avatar compliment. Yours looks pretty familiar. 😉