Engine dies while driving - tach drops to zero (MSD)

[AdamIsAdam]

I plan to run the ground wire to the starter relay, which is grounded to the battery to see if that helps. I'll also run the main power there, rather than tapping into the wire that comes from that relay. Heck, for now I may even run both wires directly to the battery just to see if that fixes the problem before cleaning up the wiring around the battery.

But just fyi, the instructions state that the chassis is an acceptable ground (see attached). Again, just sharing of info because, well, I'm the one having issues, so I'm certainly not trying to reject any advice - far from it!

[jhv48]

If you can’t figure this out right away, log into the FFR forum and pose the problem to them. FFR ignition switches have been known to fail.

[AdamIsAdam]

Originally Posted by jhv48

If you can’t figure this out right away, log into the FFR forum and pose the problem to them. FFR ignition switches have been known to fail.

I did see that. I ordered this switch that I read some builders have used on customer cars; it arrives this week.

[KDubU]

Originally Posted by AdamIsAdam

I plan to run the ground wire to the starter relay, which is grounded to the battery to see if that helps. I'll also run the main power there, rather than tapping into the wire that comes from that relay. Heck, for now I may even run both wires directly to the battery just to see if that fixes the problem before cleaning up the wiring around the battery.

But just fyi, the instructions state that the chassis is an acceptable ground (see attached). Again, just sharing of info because, well, I'm the one having issues, so I'm certainly not trying to reject any advice - far from it!

Adam,

Body is a fine ground if it’s done correctly. No powder coating can remain where one grounds and I have seen some that did not do this. They thought the hole drilled through the metal was sufficient. Electrical issues suck big time as they can be hard to find. I had an issue and everyone told me it had to be a ground, well it turned out to be a badly crimped connector for me. Drive me nuts for a coupe days and I only found it after exhaustive trouble-shooting.

[HighPlainsDrifter]

Hi,
The white wire from the msd box will kill your engine if it is shorted. I would make sure it is double taped up.
Perry

[AdamIsAdam]

White wire is nicely capped and isolated from any grounds.

Now that I've really peeled back the harnesses behind the dash I see that this will be an easy rewire with 12ga.
(now if I could only get 12ga wire without violating social distancing rules in my area! I am all out of 12ga of cours!)

[AdamIsAdam]

Reporting back:

I just rewired the positive and negative 12ga wires directly to the battery, and also added an in-line LED on the power lead coming from the ignition switch. (The LED shows power in ON, CRANK and not ACC.)

The car fired right up. I also checked for spark which is all good. It's dark and getting late, so the real test will be done over longer drives this weekend. I'll report back.

Thanks for the tips so far. Hopefully wiring home runs directly to the battery will solve the problem. Oh, and if it's the ignition switch, I have a new one ready to go in. I am NOT looking forward to that painful job so let's hope that's not my issue.

Thanks.

[Moto One]

let's hope for the best Adam.

Mark.

[patrickt]

Originally Posted by AdamIsAdam

Oh, and if it's the ignition switch, I have a new one ready to go in. I am NOT looking forward to that painful job so let's hope that's not my issue.

That is not a painful job. At all. The hardest part is just making a little tool that helps you unscrew the bezel from the dash, Then the switch just pulls out from the rear. On an ERA you have to grind down one of the little ceramic separators between the poles on the back of the switch because it hits the lip on the bottom of the dash. If your existing switch doesn't have that ground down then you can ignore that piece of advice. Other than that, an ignition switch switcheroo is a 15 minute job. Pulling the switch will also give you an appreciation for how unbelievably easy it is to hot wire a Cobra's ignition. Most of us could start your car without a key just as quickly as you can start it with one.

[AdamIsAdam]

The reason I say it's a PITA to do this is because there's a dash brace directly under the switch blocking access. And I also do not know how much slack there is to pull the switch down and do the work below the dash as opposed to being on my back with my feet dangling over the roll bar! Otherwise, i agree, it's a basic job.

I'll take it out this afternoon and report back. I'll take my Hagerty Roadside Assistance number with me. lol

[AdamIsAdam]

Got to take it for a nice 15 minute ride today and experienced no problem whatsoever. Knock wood. Then the rain started closing in on me.

[Gaz64]

Originally Posted by AdamIsAdam

Reporting back:

I just rewired the positive and negative 12ga wires directly to the battery, and also added an in-line LED on the power lead coming from the ignition switch. (The LED shows power in ON, CRANK and not ACC.)

The car fired right up. I also checked for spark which is all good. It's dark and getting late, so the real test will be done over longer drives this weekend. I'll report back.

Thanks for the tips so far. Hopefully wiring home runs directly to the battery will solve the problem. Oh, and if it's the ignition switch, I have a new one ready to go in. I am NOT looking forward to that painful job so let's hope that's not my issue.

Thanks.

I hope this is an LED paralleled off the power lead to ground. I don't know of any LED that could be connected in series.

[AdamIsAdam]

Originally Posted by Gaz64

I hope this is an LED paralleled off the power lead to ground. I don't know of any LED that could be connected in series.

Hmm, I'm not even sure it's an LED actually. I just tapped into the power line and connected the ground.

[Gaz64]

Ok, that's good, that's what we want.
Performs the same function as a mechanic's test lamp or multimeter etc.

[AdamIsAdam]

I just realized I never circled back to post that the car is fixed. Running new 12ga lines directly to both battery terminals did the trick. I left in that test light just in case I ever need it. It's attached to the wiring harness behind the glove box and visible by just looking up there, so easy to see it.

Thanks all.