Ran out of gas...now rough idle...vacuum leak? - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**ga-stepside** · 04-13-2019, 04:59 PM

Quote:

Originally Posted by Mbeef61

Does it need to be running?

No, I doubt you could keep it running with both idle screws out anyway.

**'68OrangeSunshine** · 04-13-2019, 05:14 PM

Are your Power Valve[s] FUBAR?

**ga-stepside** · 04-13-2019, 05:33 PM

Quote:

Originally Posted by '68OrangeSunshine

Are your Power Valve[s] FUBAR?

Good point on older Holley' a backfire almost always killed the power valve.

rcazwillis · 04-13-2019, 05:59 PM

Check power valve. Symptoms indicate power valve is shot.

**Mbeef61** · 04-17-2019, 10:46 AM

Quick update for those who may have this issue in the future.

I tried the damp rag while revving technique but that didn’t help. What appeared to fix it was removing the idle mixture screws, blasting with carb cleaner, and then blasting lightly with compressed air. I had to then adjust the idle because the PO appears to have not adjusted them evenly. Idle well now at about 800rpm with vacuum at 20.

Truck had sat for 6 years. I changed all the soft fuel lines. But the tank had a good amount of white scale in it. Sending unit also was completely rusty and the little bag filter on the end was disintegrated. I have wanted to relocate the tank so I’m going to get a Boyd’s tank.

Thanks for the help everyone.

**Steeveedee** · 04-18-2019, 10:10 AM

The sweet smell of exhau...success!

04-13-2019, 05:14 PM	#27
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,064	Re: Ran out of gas...now rough idle...vacuum leak? Are your Power Valve[s] FUBAR? __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

04-13-2019, 05:59 PM	#29
rcazwillis Registered User Join Date: Aug 2013 Location: Fort Worth, TX Posts: 309	Re: Ran out of gas...now rough idle...vacuum leak? Check power valve. Symptoms indicate power valve is shot. __________________ Zane's 71 Build

04-17-2019, 10:46 AM	#30
Mbeef61 Senior Member Join Date: Jun 2009 Location: Portland - OR Posts: 242	Re: Ran out of gas...now rough idle...vacuum leak? Quick update for those who may have this issue in the future. I tried the damp rag while revving technique but that didn’t help. What appeared to fix it was removing the idle mixture screws, blasting with carb cleaner, and then blasting lightly with compressed air. I had to then adjust the idle because the PO appears to have not adjusted them evenly. Idle well now at about 800rpm with vacuum at 20. Truck had sat for 6 years. I changed all the soft fuel lines. But the tank had a good amount of white scale in it. Sending unit also was completely rusty and the little bag filter on the end was disintegrated. I have wanted to relocate the tank so I’m going to get a Boyd’s tank. Thanks for the help everyone. Last edited by Mbeef61; 04-18-2019 at 10:14 AM.

04-18-2019, 10:10 AM	#31
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,114	Re: Ran out of gas...now rough idle...vacuum leak? The sweet smell of exhau...success! __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA



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