62 Just shuts off at idle, help!

[Bob H.]

My 62 340 hp has developed a problem that is intermittant, of course so it will be difficult to find.

When at idle, the car just quits. It is as though it ran out of fuel. However, it only happens at idle and never under acceleration.

I checked the carb and when pressing the gas there is fuel and it will immediately fire back up and idle and run fine. There have been a couple of times where it fires right up and quits like 3 or 4 times in a row. It will then decide to idle ok again. The carb, filter and fuel pump have been eliminated as the problem.

I'm beginning to think it may be electrical although as I said it will fire up right away and either be ok or shut off right away. Any ideas on how to diagnose this?

Thanks for any help!!

[Bruce B.]

Re: 62 Just shuts off at idle, help!

With thw air filter off try moving the accelerator rod after it dies. Did the acceleraor pump squirt fuel?
If not it could be a fuel problem.

[Dave S.]

Re: 62 Just shuts off at idle, help!

My 62 340 hp has developed a problem that is intermittant, of course so it will be difficult to find.

When at idle, the car just quits. It is as though it ran out of fuel. However, it only happens at idle and never under acceleration.

I checked the carb and when pressing the gas there is fuel and it will immediately fire back up and idle and run fine. There have been a couple of times where it fires right up and quits like 3 or 4 times in a row. It will then decide to idle ok again. The carb, filter and fuel pump have been eliminated as the problem.

I'm beginning to think it may be electrical although as I said it will fire up right away and either be ok or shut off right away. Any ideas on how to diagnose this?

Thanks for any help!!

You may want to check your ignition coil............

[Bob H.]

Re: 62 Just shuts off at idle, help!

Hi Bruce.

It has gas when you hit it and strats right up. That's why I'm thinking it may be electrical. I just don't know why it would shut off and usually fire right back up. I have driven the car 20 miles after it happened without any issues.

On two occasions it would fire and quit 3-4 times in a row and then be fine. Other times it happens only once and is then ok. I'm lost but think I'll check for a loose wire.

[Bob H.]

Re: 62 Just shuts off at idle, help!

Hi Dave. Is that something that could be intermittant? I think I have a spare so I'll try that. Thanks.

[Dave S.]

Re: 62 Just shuts off at idle, help!

Hi Dave. Is that something that could be intermittant? I think I have a spare so I'll try that. Thanks.

Could be intermittent.
A coil change is simple enough. Give it a try.

[Timothy B.]

Re: 62 Just shuts off at idle, help!

Bob,

If your car was a 63 I would suggest to check the engine harness plug at the firewall. If 62 is the same you might want to look there.

Put a test light on the wire going to the coil + when it dies and that will tell you if the there is a problem in the primary wiring.

[Rich G.]

Re: 62 Just shuts off at idle, help!

Don't know the weather conditions where you are, but it is possible to get carb ice anywhere between 40 and 70 F at least with high humidity. I don't have any idea what these cars use to prevent carb ice, but if there is something, that could be not working.

My experience with carb ice is in airplanes and several MGB's I have owned. Symptoms are the same. I once drove the MGB 40 miles on a highway and when I got off, it quit. Started right up again once the heat melted the ice.

Long shot, but it comes to mind. I would try the other suggestions first.

Rich

[Stuart F.]

Re: 62 Just shuts off at idle, help!

Also take a check of the Ballast Resistor. Your description sounds like it starts fine on the by-passed 12 volts, then goes chicken when routed back through the resistor. I've had that happen years ago. Also, where is your normal idle speed setting?

Stu Fox

[John F.]

Re: 62 Just shuts off at idle, help!

Also check the primary wire from the distributor to the coil. I had that happen a long time ago. The wire started to break. It must have been crimped at one time or another.

John

[Jim D.]

Re: 62 Just shuts off at idle, help!

I had the exact problem. Intermittent, would restart right away 99% of the time, sometimes it had to sit for a couple of minutes then it would start. Sometimes it wouldn't do it for months, other times it would do it once a day. This went on for 2 years. I checked everything and found no cause. I finally mounted a light and a switch under the dash. The light was wired to the coil to indicate whether it lost power and the switch supplied 12v to the coil in case it was a wiring issue I could "hot wire" it with a flip of the switch. The problem - bad coil.

[Timothy B.]

Re: 62 Just shuts off at idle, help!

On the 250 & 300 hp cars with cast manifolds, carburetor ice is controlled by the hot slot under the carburetor.

The 340 hp aluminum manifolds conduct enough heat to the carburetor so this is not supposed to be a problem with a functioning heat riser. The more heat the engine gets under the throttle blades the better..

I would check the coil + primary wire after the engine quits as this will narrow the problem down fast. As stated by others, most times troubleshooting the coil is difficult and done by replacing the coil for a test.

[Jack H.]

Re: 62 Just shuts off at idle, help!

I would check the coil + primary wire after the engine quits as this will narrow the problem down fast. As stated by others, most times troubleshooting the coil is difficult and done by replacing the coil for a test.

Yes! That's because checking the primary and secondary windings for continuity/resistance is only HALF of the battle...

The coil is a step-up transformer. The primary and secondary windings can be fully intact and you still have problem(s). Why?

It takes a properly functioning transformer core to magnetically couple the primary and secondary sides. If the core has been damaged (coil lost cooling oil, saw electrical/thermal overstress) and the core's laminations are separating or the core has melted down, it can't do its intended job of magnetically coupling the primary/secondary windings.

That fault won't show when you meter the windings!

[Edward B.]

Re: 62 Just shuts off at idle, help!

If the ignition shielding is still in place remove the top piece and see if the problem persists.

[Bob H.]

Re: 62 Just shuts off at idle, help!

Thanks for all the input. I have changed the coil and will see what happens. If it occurs again, I like the idea of connecting a light to the coil. Hopefully, the coil will solve it and I won't have to. I'll report back.

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