Engine died-idle problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

w6tractor · 06-11-2008, 08:07 AM

Any suggestions appreciated. I have a 1972 Cheyenne 3/4 ton with an big block 402 and auto. It's been running great. Yesterday it died while driving-no cough or sputter-just died like the key was turned off. Tried to start-turned over but no luck. Thought fuel line was pinched. Straightened-no luck. Fuel was getting to carb. Thought points might be stuck-checked seemed OK. Finally restarted but idle was way high. Got it home but idle is still very high. Any thought on what might have happened? Thanks

68gmsee · 06-11-2008, 09:37 AM

Welcome to the forum...

You may have a vacuum line loose or dry cracked that's sucking in air. That usually gives you a boost in rpm.

Other thing that can cause high rpm is carburetor adjustments. If it's a quadrajet, there's a lot of links, hoses and levers that may be out of whack.

Now as to why your truck died in the first place. I'd start by checking all wires and cables to the starter and distributor for a good connection.

Also, your carb float/needle valve may have gotten stuck, it may have caused a flood condition that would have caused it not to start. I'm not sure if that will cause the rpms to go up though..

jayharrell · 06-11-2008, 11:12 AM

I would start with a carb kit. Probably a stuck float that caused it to die, and a stuck butterfly causing the high RPM.

Plus a rebuilt carb will get some MPG boost. Its just a good starting point thats cheep to do and kinda fun in my book.

Sinisterspeed · 06-11-2008, 12:02 PM

Sounds like a vacuum leak to me too. While its running and the air cleaner off. Take some carb cleaner and spray around the top of the engine without spraying right into the carb. When the engine races you found your leak.

w6tractor · 06-11-2008, 01:22 PM

Thanks to all of you. I'll check the vacuum and see where that takes me. I'm also going to change points, condenser and coil-just in case. I hate being stranded on the road. By the way-how do you list the vehicles I have as I see in other posts?

Sinisterspeed · 06-11-2008, 02:23 PM

In your USER CP at the top of the page then look on the left for signature. You can put it in there.

06-11-2008, 08:07 AM	#1
w6tractor Registered User Join Date: Mar 2008 Location: Bynum, Tx Posts: 21	Engine died-idle problem Any suggestions appreciated. I have a 1972 Cheyenne 3/4 ton with an big block 402 and auto. It's been running great. Yesterday it died while driving-no cough or sputter-just died like the key was turned off. Tried to start-turned over but no luck. Thought fuel line was pinched. Straightened-no luck. Fuel was getting to carb. Thought points might be stuck-checked seemed OK. Finally restarted but idle was way high. Got it home but idle is still very high. Any thought on what might have happened? Thanks

06-11-2008, 09:37 AM	#2
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Engine died-idle problem Welcome to the forum... You may have a vacuum line loose or dry cracked that's sucking in air. That usually gives you a boost in rpm. Other thing that can cause high rpm is carburetor adjustments. If it's a quadrajet, there's a lot of links, hoses and levers that may be out of whack. Now as to why your truck died in the first place. I'd start by checking all wires and cables to the starter and distributor for a good connection. Also, your carb float/needle valve may have gotten stuck, it may have caused a flood condition that would have caused it not to start. I'm not sure if that will cause the rpms to go up though..

06-11-2008, 11:12 AM	#3
jayharrell Gettin By on Gettin By Join Date: Jan 2008 Location: Cedar Creek, Tx Posts: 1,033	Re: Engine died-idle problem I would start with a carb kit. Probably a stuck float that caused it to die, and a stuck butterfly causing the high RPM. Plus a rebuilt carb will get some MPG boost. Its just a good starting point thats cheep to do and kinda fun in my book. __________________ 69 CST10 LWB 455 Buick 00 S10 2.2 Vin5 76 GL1000 Naked 1bl VW carb "Adios to all the concrete; Gonna get me some dirt road back streets"

06-11-2008, 12:02 PM	#4
Sinisterspeed Registered User Join Date: Apr 2008 Location: Gales Creek, Oregon Posts: 619	Re: Engine died-idle problem Sounds like a vacuum leak to me too. While its running and the air cleaner off. Take some carb cleaner and spray around the top of the engine without spraying right into the carb. When the engine races you found your leak. __________________ There are two kinds of people, those who finish what they start and so on. 70 GMC Longhorn (A.K.A Money Bucket) 57 Chev 3100 05 Chevy LLY Dmax. 67 Chevy Camaro Dad's Budget Build 55 My Longhorn Build Last edited by Sinisterspeed; 06-11-2008 at 12:03 PM.

06-11-2008, 01:22 PM	#5
w6tractor Registered User Join Date: Mar 2008 Location: Bynum, Tx Posts: 21	Re: Engine died-idle problem Thanks to all of you. I'll check the vacuum and see where that takes me. I'm also going to change points, condenser and coil-just in case. I hate being stranded on the road. By the way-how do you list the vehicles I have as I see in other posts?

06-11-2008, 02:23 PM	#6
Sinisterspeed Registered User Join Date: Apr 2008 Location: Gales Creek, Oregon Posts: 619	Re: Engine died-idle problem In your USER CP at the top of the page then look on the left for signature. You can put it in there. __________________ There are two kinds of people, those who finish what they start and so on. 70 GMC Longhorn (A.K.A Money Bucket) 57 Chev 3100 05 Chevy LLY Dmax. 67 Chevy Camaro Dad's Budget Build 55 My Longhorn Build



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