Engine 1972 Jeep CJ5 - High Idle

[Nick S]

Hi Everyone,

I have a noticeable high idle with my AMC 304 with the Motorcraft 2100 Carburetor no matter what adjustments I make to the carburetor. Any leads are greatly appreciated. Thinking vaccum lines but the diagrams are hard to find for 1972.

 

[Manic Mechanic]

Id say it's vacuum lines. Block em all off and start with the carb. Spray some carb cleaner or brake cleaner around the base. If the idle jumps then you have a leak. Fix that then repeat with the carb itself at the joints (where each section attaches). If that checks out reconnect vacuum lines one at a time until the problem returns. Then you know what section to fix

The other option is to just eliminate all of them except for vacuum advance on the distributor and power brakes (if you have them)

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[Nick S]

Id say it's vacuum lines. Block em all off and start with the carb. Spray some carb cleaner or brake cleaner around the base. If the idle jumps then you have a leak. Fix that then repeat with the carb itself at the joints (where each section attaches). If that checks out reconnect vacuum lines one at a time until the problem returns. Then you know what section to fix

The other option is to just eliminate all of them except for vacuum advance on the distributor and power brakes (if you have them)

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These are the only vacuum lines I am finding online without the manual. Do you recall if this is the complete diagram for vacuum lines or should I be looking for more not pictured?

 

[Manic Mechanic]

I'll try to snag a few pics of the 79 AMC 304 at home in a bit. There's not many hence why I mentioned blocking them all off and starting with the carb

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[Nick S]

Thank you and no rush. I think I found the culprit but I'm doing the complete test anyway to make sure I catch them all while I've got it apart. Cutting corners has gotten me no where with this thing!

 

[Manic Mechanic]

Not the best picture. And I have a few more vacuum lines than you since this is a quadra Trac system.

But I'd still block them all off and start with the carb. Also best time to get it tuned and running correctly that way if it changes as you add the components back in you can tell if there working correctly or have an issue

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[Nick S]

Thanks so much. These photos will work as a great reference for my year. And yes I will get in there and get it tuned and running correctly. Been putting this off for 6 months and today is the day!