# 1966 389 Runs, stalls, starts itself, stalls, starts itself...



## Sixtydriver (5 mo ago)

If this isn't the right forum then Mods please move it. Having an recent (today) issue with my 389 tri-power. Starts immediately and idles high for a few minutes, just like normal for it. After it idled down (about 1000) and the temps were up I took it for the daily spin. Driving down the road at about 35 the RPM dropped to zero for about half a second and then right back up to where it was. I assumed electrical since I could not hear the engine. Pulling into the gas station it happened again and I can confirm that the engine was off for about half a second each time. I filled it up and it cranked just fine and drove the two miles home with no issues. Going out to start it again about a half hour later and the problem returned sitting in Park. It will "stall" two or three times and then run fine for a minute or two. Only happens after giving it gas to increase the RPMs. So my question, where would I look first for this problem? I have a video but it is too large to mail myself. 

I can tear down and rebuild a turbine engine but this stuff is currently out of my wheelhouse.

Thanks in advance


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## armyadarkness (Dec 7, 2020)

I had a bad fusible link on a 70 vette once, and thats exactly what it did.

I would check your ignition wire very welland make sure that theres not a corroded connection or break in it.


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## armyadarkness (Dec 7, 2020)

Is anything else turning off? If you loose ALL power, then it's probably a main wire at the starter or alternator.

If it's just the ignition, then its likely just in the ignition circuit.


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## Sixtydriver (5 mo ago)

armyadarkness said:


> Is anything else turning off? If you loose ALL power, then it's probably a main wire at the starter or alternator.
> 
> If it's just the ignition, then its likely just in the ignition circuit.


Thanks Army. After talking with some people around here that's the direction I was pointed to. I haven't tried it with any accessories on, I'll give that a shot. Appreciate it.


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## geeteeohguy (Feb 2, 2008)

Check the bulkhead connectors at the firewall (under the master cylinder). I will say, when it's a connection issue at the bulkhead, NOTHING works, not just the ignition. Also check the wiring from the ignition switch to the ignition coil. You can connect a DVOM to the ignition coil or a test light and look at it as you drive. If the voltage drops or stops, you know it's likely that issue.


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## Sixtydriver (5 mo ago)

I appreciate the replies. I found this weird problem [Archive] - PY Online Forums - Bringing the Pontiac Hobby Together from years ago and it's the exact problem as mine. Fuel is absolutely fine, pump and filter are pristine (couple months old for both). Going with electrical (ignition/distributor/etc) to see what happens. The bay was a jumble of Radio Shack electrical tape when I got it and all of that has been replaced with crimp connectors and all wires are tucked into looms. I was a helicopter test pilot in the Army and I'm not above throwing parts at it until it's fixed lol.


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## BLK69JUDGE (Jun 10, 2010)

how many keys on your cars key chain....

I have had tired ignition switches act like that ...


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## Sixtydriver (5 mo ago)

BLK69JUDGE said:


> how many keys on your cars key chain....
> 
> I have had tired ignition switches act like that ...


I'm a believer in that as well. Ignition and trunk key, that's it. Plus the pewter goat lol.


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## Sixtydriver (5 mo ago)

Replaced the coil, ignitor, and rotor yesterday and it runs like a champ. Not sure what the issue was and at this point I guess it doesn't really matter. Just glad to maybe have her back in shape. Thank you all for the advice.


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## geeteeohguy (Feb 2, 2008)

Sixtydriver said:


> Replaced the coil, *ignitor, *and rotor yesterday and it runs like a champ. Not sure what the issue was and at this point I guess it doesn't really matter. Just glad to maybe have her back in shape. Thank you all for the advice.


Aha! You didn't mention that you had an HEI 'upgrade'. My money is on a bad module or pick-up coil that caused your issue. Usually is.


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## Sixtydriver (5 mo ago)

geeteeohguy said:


> Aha! You didn't mention that you had an HEI 'upgrade'. My money is on a bad module or pick-up coil that caused your issue. Usually is.


Well I have said before that I don't know S from Shinola about internal combustion engines but I'm learning lol. It runs, I'm good.


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## PontiacJim (Dec 29, 2012)

Sixtydriver said:


> Well I have said before that I don't know S from Shinola about internal combustion engines but I'm learning lol. It runs, I'm good.


Make sure you have 12 Volts at the + Coil while the engine is running. These cars used a resistor wire to drop down the starting 12Volts to fire up the engine to around 7-9 volts so you did not burn up the points. If you don't have the needed 12V going to the HEI with the engine running, you can have issues and may burn up another module.

So just check with a volt meter - easy enough. You can get an inexpensive hand held unit at Lowes/Home Depot, or auto store and it is a good tool to have should you need to do any wire work or testing.


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## Sixtydriver (5 mo ago)

Thanks Jim. I'll take a look at it. I have a few multimeters from my former life that are lying around. Appreciate the tip.


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## PontiacJim (Dec 29, 2012)

Sixtydriver said:


> Thanks Jim. I'll take a look at it. I have a few multimeters from my former life that are lying around. Appreciate the tip.


Also check that the 12V source wire is large enough gauge wire. I recall we had a member who simply went with a larger gauge wire for the HEI and that did the trick - his engine was able to rev higher. Apparently the smaller wire gauge was creating too much resistance and not supplying enough electrical flow (Amps?) even though testing showed 12V.


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