Truck running rough at idle, dying when hot. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jobe72 · 03-25-2011, 06:17 PM

I have 1972 GMC with the stock 350/350 combo. Nothing has been done to the engine that I know of. I am running an Edelbrock carb and converted the engine to HEI. Been running great for the last year that I have owned it and I love droving it. In the last week or so it's been getting warmer down here in Texas. Today while on a road trip when I would come to a stop the truck would idle really rough and want to die unless I gave it a little rev up. Runs great, no problems and I haven't changed anything. Does not do this when cold, starts right back up no problem.

Any thoughts? Ethanol in the gas? Not sure where to start on this one...yes, I've checked all the hoses and everything under the hood.

Thanks

dadsworktruck · 03-25-2011, 06:23 PM

Corn is best to eat not fuel our trucks, but i'll refrain from soapboxing too much.....check the base gasket for sealing carb to manifold, might have burnt thru...

68gmsee · 03-25-2011, 08:53 PM

My first guess I'd say it's running rich. The second guess is not enough fuel.
Can't go wrong there but aside from vacuum leaks either one could cause those symptoms.

After you check the carb filter, place the end of the fuel line in a plastic container and crank the engine. You should get at least a pint in around 30 seconds or less. Pump pressure should be around 8 psi.

03-25-2011, 06:17 PM	#1
Jobe72 Registered User Join Date: Mar 2010 Location: Austin, TX Posts: 299	Truck running rough at idle, dying when hot. I have 1972 GMC with the stock 350/350 combo. Nothing has been done to the engine that I know of. I am running an Edelbrock carb and converted the engine to HEI. Been running great for the last year that I have owned it and I love droving it. In the last week or so it's been getting warmer down here in Texas. Today while on a road trip when I would come to a stop the truck would idle really rough and want to die unless I gave it a little rev up. Runs great, no problems and I haven't changed anything. Does not do this when cold, starts right back up no problem. Any thoughts? Ethanol in the gas? Not sure where to start on this one...yes, I've checked all the hoses and everything under the hood. Thanks __________________ 1972 GMC Sierra LWB (Aquafresh) 1962 Cadillac Convertible 1962 Cadillac Sedan project

03-25-2011, 06:23 PM	#2
dadsworktruck Registered User Join Date: Jul 2009 Location: blacksburg,s.c. Posts: 155	Re: Truck running rough at idle, dying when hot. Corn is best to eat not fuel our trucks, but i'll refrain from soapboxing too much.....check the base gasket for sealing carb to manifold, might have burnt thru...

03-25-2011, 08:53 PM	#3
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Truck running rough at idle, dying when hot. My first guess I'd say it's running rich. The second guess is not enough fuel. Can't go wrong there but aside from vacuum leaks either one could cause those symptoms. After you check the carb filter, place the end of the fuel line in a plastic container and crank the engine. You should get at least a pint in around 30 seconds or less. Pump pressure should be around 8 psi.



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