Can't get idle down ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

RShaips · 05-11-2005, 10:55 AM

I just bought a 72 4x4 with a 350 and a Quadrajet carb. This truck had been sitting for quite a while. After I got it I replaced the gas tank and rebuilt the carb . Since I rebuilt the carb I can't adjust the idle down, its high like 2000 rpm plus. I can pull the throttle foreward and get it lower but it will not adjust any lower, feels like something is holding the linkage back. Any ideas, I have not taken the carb back apart yet. thanks

jhow66 · 05-11-2005, 11:20 AM

Check this 1st:

RShaips · 05-11-2005, 11:26 AM

I am pretty sure it is ok, i will check it again. thanks

vtblazer · 05-11-2005, 01:01 PM

Check for vacuum leak's.

jhow66 · 05-11-2005, 02:36 PM

Next check to see that secondary blades are closing.

OhioDan · 05-11-2005, 02:38 PM

Might check yer throttle linkage, and make sure that's not holding the carb open? Just my $.02 .

CPNEJR · 05-11-2005, 03:14 PM

I had the same problem

I think you might have a vaccum leak. I had one from an extra gasket between the spacer and the carbafter that was out it ran great.

Faster_than_you · 05-11-2005, 04:27 PM

Just like another said check the throttle spring and linkage. the linkage might need just some adjustment out, and some general purpose lubricant (wd-40, or whatnot) and the spring might not be the correct size, or might have not enough "springiness"

**StingRay** · 05-11-2005, 05:08 PM

Check to make sure the choke is coming all of the way off. This will realate directly to jhow66's pic of the fast idle cam as the fast idle cam is controlled by the choke.

RShaips · 05-11-2005, 06:23 PM

Bottom linkage was stuck under choke, now it idles ok just runs like sh$t! I love playing with new toys! I don't think my fuel pump is pumping correctly, it doesn't seem to put out a good steady flow. There was so much crap in the old gas tank that there may be some still in the fuel pump. I will buy a new one tommorrow. Thanks for the help

Robert1970C20rstbukt · 05-11-2005, 06:57 PM

If there's a lot of junk in the tank, it might be a good idea to run an extra filter between the tank and fuel pump.

05-11-2005, 10:55 AM	#1
RShaips Senior Member Join Date: Jun 2002 Location: Augusta Missouri Posts: 804	Can't get idle down ? I just bought a 72 4x4 with a 350 and a Quadrajet carb. This truck had been sitting for quite a while. After I got it I replaced the gas tank and rebuilt the carb . Since I rebuilt the carb I can't adjust the idle down, its high like 2000 rpm plus. I can pull the throttle foreward and get it lower but it will not adjust any lower, feels like something is holding the linkage back. Any ideas, I have not taken the carb back apart yet. thanks

05-11-2005, 11:20 AM	#2
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Check this 1st: Attached Images __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

05-11-2005, 01:01 PM	#4
vtblazer Registered User Join Date: Oct 2003 Location: Central Vermont Posts: 8,538	Check for vacuum leak's. Last edited by vtblazer; 05-11-2005 at 01:01 PM.

05-11-2005, 02:36 PM	#5
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Next check to see that secondary blades are closing. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

05-11-2005, 02:38 PM	#6
OhioDan Registered User Join Date: Apr 2002 Location: New Carlisle, Ohio,USA Posts: 1,404	Might check yer throttle linkage, and make sure that's not holding the carb open? Just my $.02 . __________________ LIFE AIN'T EASY WHEN YER FAT AND GREASY! GMC= Got More Class! 1970 GMC LWB, Fleetside, 350/4spd, Flowmaster "40's", 2002 GMC 16" Rallies, cowl hood,and added a bunch of options that weren't there when I started.

05-11-2005, 11:26 AM	#3
RShaips Senior Member Join Date: Jun 2002 Location: Augusta Missouri Posts: 804	I am pretty sure it is ok, i will check it again. thanks

05-11-2005, 03:14 PM	#7
CPNEJR Registered User Join Date: Sep 2003 Location: Franconia,N.H. Posts: 1,029	I had the same problem I think you might have a vaccum leak. I had one from an extra gasket between the spacer and the carbafter that was out it ran great. __________________ (Only) Member of the CPNE Fan Club Aint that the truth 67 C-10 350 with 3-speed tranny and 308 gears swb step 82 Z28 Camaro 355 small block over 350 hp and a borg warner super t-10 (blown engine) 72 Chevy K20 Suburban (future project) 70 Chevy K20 now 68 GMC K2500 2003 Chevy 2500hd ccsb 4X4 (daily driver)

05-11-2005, 04:27 PM	#8
Faster_than_you Registered User Join Date: Mar 2004 Location: Virginia beach, Va Posts: 209	throttle spring/linkage Just like another said check the throttle spring and linkage. the linkage might need just some adjustment out, and some general purpose lubricant (wd-40, or whatnot) and the spring might not be the correct size, or might have not enough "springiness" __________________ ~Christopher L. Orr 71 c20, 454- Stolen While Deployed. dynoed at 550 ft lbs, 425 hp at 3000 rpm (mustang dyno). TH400 3500 stall.... etc, etc.

05-11-2005, 05:08 PM	#9
StingRay Senior Member Join Date: Mar 2000 Location: Saskatoon,SK,Canada Posts: 2,476	Check to make sure the choke is coming all of the way off. This will realate directly to jhow66's pic of the fast idle cam as the fast idle cam is controlled by the choke. __________________ Saskatoon, Saskatchewan Canada

05-11-2005, 06:23 PM	#10
RShaips Senior Member Join Date: Jun 2002 Location: Augusta Missouri Posts: 804	Bottom linkage was stuck under choke, now it idles ok just runs like sh$t! I love playing with new toys! I don't think my fuel pump is pumping correctly, it doesn't seem to put out a good steady flow. There was so much crap in the old gas tank that there may be some still in the fuel pump. I will buy a new one tommorrow. Thanks for the help

05-11-2005, 06:57 PM	#11
Robert1970C20rstbukt Registered User Join Date: Jun 2004 Location: Beeville, Texas Posts: 1,943	If there's a lot of junk in the tank, it might be a good idea to run an extra filter between the tank and fuel pump. __________________ RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck



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