2 problems--electrical, and stalling at idle - Vintage Mustang Forums
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post #1 of 7 (permalink) Old 06-30-2018, 02:12 PM Thread Starter
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2 problems--electrical, and stalling at idle

Long time no talk folks. Only had my car out twice this year now.

I drove it into work the other day and as always, it's a perfect running machine. It was a cooker that day, close to 90 degrees.

I have two issues that happened simultaneously, what's your take on them?:

1. The dome light (Scott Drake unit) stopped working sometime back. Hadn't looked into because I'm lazy. Now the domelight stays ON and doesn't shut off (and drained the battery as I didn't realize it was on). To shut it off I have to disconnect the battery. I'm wondering if one of the door jamb switches went bad so the circuit is permanently closed. If I disconnect one switch to trouble shoot, would the other still work? Any other suggestions would be great.

2. Second issue--I had to replace the powervalve a few years ago, this is a 67 Coupe with 5.0 and Holley 600. It has been running with some very slight hesitation on initial acceleration, just a light stumble. Well, when I was trying to get it started up in the parking lot, it was hard to start. I had to crank it for awhile, usually just fires up. I'm running a Pertronix 3 ignition. Slowing down to a stop at idle speed, whether in gear or neutral, it would almost stall out unless I gave it some gas. Also, as I was driving, at 1500 rpm I would hear a very low rumble that went away as rpm increased. It's just weird how driving in it would be perfect and then have this issue after sitting there. I'm suspecting it's carb related.


67 coupe with 5.0 and C4 (Viper GTS Blue, paint code PBE, since everybody asks)
69 Mach 1 428 SCJ drag pack
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post #2 of 7 (permalink) Old 06-30-2018, 02:32 PM
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The interior lights are controlled by two door switches and the knob on the light switch can be rotated counter-clockwise to turn the light on also. So first be certain that the knob is not rotated fully counter-clockwise with the doors closed, and if the light is still on remove one door switch. I've not looked at these in some time so I don't remember what that entails. Make sure the other door is closed. If the light is still on, remove the other switch. If the light is still on the power has to be coming from the light switch, or a short to a hot wire somewhere (very unlikely).
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post #3 of 7 (permalink) Old 06-30-2018, 03:01 PM
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Check to see if the plunger on the door jamb switch hasn't broken off. This has happened to me several times the last few years. Luckily I've noticed the interior lights on before walking away for awhile and not coming back to a dead battery.



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1965 Fastback, 289, Toploader 4 Speed, owned by me since June 1980. Originally a C-code with a C-4. 5R09C16****
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post #4 of 7 (permalink) Old 06-30-2018, 08:30 PM Thread Starter
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Check to see if the plunger on the door jamb switch hasn't broken off. This has happened to me several times the last few years. Luckily I've noticed the interior lights on before walking away for awhile and not coming back to a dead battery.
both plungers are good, I worked both sides well to see if it would shut the light off, which it didn't. I guess I just need to troubleshoot one at a time by taking them out individually.


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69 Mach 1 428 SCJ drag pack
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post #5 of 7 (permalink) Old 06-30-2018, 11:30 PM
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Quote:
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both plungers are good, I worked both sides well to see if it would shut the light off, which it didn't. I guess I just need to troubleshoot one at a time by taking them out individually.
I didn't see that you checked the headlight knob as Mach 1 Driver suggested. If you turn the knob all the way to the left it'll click and turn the dome light on.
2nd issue: when you tried to start it in the parking lot, how long was it off? What generally happens is, if the engine is still at operating temp when you try to start it, the choke closes like the engine is cold. Try just turning the key without pumping the gas first (which closes the choke). Let it run for a minute or two before clicking it into gear to let the choke know it's supposed to be open.

69 Convertible, 351W, T5, E-Brock Performer 351-W intake, Performer Plus cam, Holley 4160, power assist, dual exhaust, 4-wheel manual drums.
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post #6 of 7 (permalink) Old 07-01-2018, 08:18 AM Thread Starter
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I didn't see that you checked the headlight knob as Mach 1 Driver suggested. If you turn the knob all the way to the left it'll click and turn the dome light on.
2nd issue: when you tried to start it in the parking lot, how long was it off? What generally happens is, if the engine is still at operating temp when you try to start it, the choke closes like the engine is cold. Try just turning the key without pumping the gas first (which closes the choke). Let it run for a minute or two before clicking it into gear to let the choke know it's supposed to be open.
I had initially tried the headlight knob when I noticed the dome light wouldn't shut off.

As for the second issue, the car had been sitting in the parking lot for about 8 hours. My initial thought was if it was so hot the fuel had evaporated from the fuel bowl or it was vapor locked, but I really doubt it was either of those. I've never actually experienced vapor lock.


67 coupe with 5.0 and C4 (Viper GTS Blue, paint code PBE, since everybody asks)
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post #7 of 7 (permalink) Old 07-01-2018, 11:46 PM
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Might be something simple like the fuel filter. If you change it and it doesn't help it might need the floats adjusted. I'm no expert on carbs... but I have 2 Holley 6150s. The one I have on my car now's been there since I bought it. It's on it's 3rd engine. I'd rebuilt the other one, but when I put it on the engine it ran like crap.
My carb (the old one) sprung a few leaks earlier this year. When I pulled the old floats my plan was to use the newer ones from the carb that didn't work very well. I took note of the number of threads where the old floats were adjusted to, matched them to the newer floats, installed the new ones, and everything is working nicely.

There are a number of people more qualified here to help with carb issues, but I thought I'd just throw this out there.

From what I understand, the floats regulate how much fuel is allowed into the bowls. If they're not adjusted correctly, you could starve the engine, or flood it.

69 Convertible, 351W, T5, E-Brock Performer 351-W intake, Performer Plus cam, Holley 4160, power assist, dual exhaust, 4-wheel manual drums.

Last edited by FrankieThe69Kid; 07-01-2018 at 11:48 PM.
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