Stalls while driving

[Rindelmach1 14]

Hey guys, 

recently my 69 mach 1 occasionally stalls while driving and I noticed that my voltmeter gauge also loses power. So I assume I'm losing electrical.  Its a new battery and I checked battery cables, engine ground and other wiring.  I can't seem to figure out why she does this.  I do notice that after stalling, I can start it but then it starts happening more frequently.  After a few stalls, the ingition key does not always kick the engine.  After a few attemps of twisting the key, she gets power and turns over.  Any ideas?

I was thinking possible ignition switch. 

[barnett468 418]

these types of problems suck cuz they can be extremely hard to track down without simply changing parts until it is fixed.

you can start by checking the voltage going to the battery with the lights off then the lights on both at idle then at around 1500 - 2000 rpm.

might also be the starter solenoid. next time it won't start with the key you can touch the big front battery post on the solenoid to the small post right next to it with a screwdriver and see if it turns the engine over.

if it has points, make sure they are good and the gap is good. a new condenser is cheap and wouldn't hurt. they sometimes cause intermittent problems.

also, a weak coil or an original scott drake repo coil can cause intermittent running problems when they get hot but won't affect the engine turning over.

the ignition switch may be expensive, so i would check the less costly things first.

 

.

 

 

[Rindelmach1 14]

is this what I need to replace the ignition switch?
https://www.cjponyparts.com/ignition-switch-assembly-1968-1969/p/ISA3/

[1969_Mach1 333]

Yes, that looks like the ignition switch for a 1969 Mustang.  I got mine from NAPA auto parts instead of mail ordering it.  Might not fix everything.  But like barnett468 mentioned, sometimes with intermittent problems you have to start changing parts that can contribute to the issue.

[barnett468 418]

yeah, you might want to see if you can get one from a local auto parts store even if it costs a few dollars more because it is a lot easier and faster to return to them if it goes bad, plus, you can return some electrical parts to some parts suppliers if you find out you didn't need it. the good brands used to be smp (standard motor products), and bwg (borg warner) although even these places have a lot of parts made "overseas" now.

 

 

 

 

 

 

[Rindelmach1 14]

I assume that the ignition switch will come with new set of keys?

[RPM 1,190]

The few I've bought came with keys. But it won't match your door locks, so...

[1969_Mach1 333]

It should have come with keys.  Where did you purchase it from?

[barnett468 418]

1 hour ago, Rindelmach1 said:

I assume that the ignition switch will come with new set of keys?

Like RPM, all the ones I have bought have also come with keys. If you want the ignition key to match the door key, you can take the old and new lock assembly and the old and new keys to a locksmith and they can change the pins in the cylinder. It costs me round $35.00 to have that done where I live.

 

 

[Midlife 814]

You might be able to simply transfer the key tumbler from the old ignition switch to the new one, keeping your key the same.

[nymustang1969 22]

Motorcraft switch is still available new. Just got one from Rock Auto. You transfer the key tumbler from your old switch to the new one. Easy to do, only special tool required is a paper clip. In my case the wiring plug that goes into the switch was melted and had to be replaced with a new pigtail. I understand that this has been a problem for a long time as the origional Motorcraft switches would come with a new wiring pigtail.

[RPM 1,190]

On 10/7/2018 at 4:27 PM, Midlife said:

You might be able to simply transfer the key tumbler from the old ignition switch to the new one, keeping your key the same.

Oh ya. And I've done this myself. On my 69. Now I member, you member eh?

[Rindelmach1 14]

Problem fixed by replacing switch with BWD Ignition Starter Switch i bought from advanced auto parts.  It didnt come iwth key tumbler so i was able to save a few dollars and use my own tumbler and key. 

[barnett468 418]

Xlnt, plus you correctly diagnosed your problem in your first post, so it looks  like I for one may be asking YOU for help if I ever have an electrical problem  lol.

[Brian Conway 264]

Thanks for posting the results.  Nice to hear a happy ending to one of these stories.  Brian