need some tech help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Bowed · 01-02-2003, 08:57 PM

took one of my trucks for emmissions today ( its either a 230 or a 250 6 CLY ) and it passed every thing except the idle test . here are the readings.

(HC) in PPM idle standard 250 Actual reading 885 ( FAIL )
(CO) in % idle standard 2.00 Actual reading 5.88 ( FAIL )

(HC ) in PPM loaded standard 250 Actual reading 124 ( PASS)
(CO ) in % loaded standard 1.50 Actual reading .57 ( PASS)

Is this just the wrong idle adjustment on the one barrel carb or do the figures indicate some thing more involved . Also during the test we did not know the thermostat had become stuck and by the time the test was done the truck had over heated real bad , could too hot an engine cause that bad idle reading ?? It turned out to be a real sh***y day , on the way back the truck was over heating so bad , we wound up pushing the truck the last 2 blocks just to get home . Thanks for your help .

JHickson6 · 01-02-2003, 09:09 PM

ahhhh thats no good! Not sure about your actual questions but before you go back again try some of those carb cleaners and emissions passing chemicals.

Just a thought!

Bowed · 01-03-2003, 01:04 AM

ttt

**GMCPaul** · 01-03-2003, 03:44 AM

I believe your idle mixture settings are to rich, time and adjust carb with a vaccum guage and tune it up with new plugs, wires, cap, & rotor or switch to HEI distributor. I give step by step instructions on the following page of our site
http://www.gmcpauls.com/Tech%20Tips1.htm
You will want the section " Vacuum Gauge Use "
Between doing that and
Before returning get the overheating solved thats really hard on a 6cyl motor running it till it won't run, VERY easy to crack the head on them by the thermostat, install a new thermostat, and a fan shroud if yours is missing, add a mixture of 50/50 anti-freeze and water not all water even if you live where it never freezes as anti-freeze helps it to run cooler also.
GMCPaul

Bowed · 01-03-2003, 11:11 AM

GMC Paul , thanks for the tech input and I will follow your advice and then see if I can get it passed . The overheating problem has been solved , has it turned out the guy I had just bought the truck from had dropped a ton of the older type radiator sealing pellets into the cooling system and had every thing from the thermostat to the heater hoses pluged up , what a mess . I hope I did not damage the motor , it did get so hot it was starting to detoniate before I was able to shut it down for good .

01-02-2003, 08:57 PM	#1
Bowed Registered User Join Date: Oct 2002 Location: where it's hot Posts: 1,059	need some tech help took one of my trucks for emmissions today ( its either a 230 or a 250 6 CLY ) and it passed every thing except the idle test . here are the readings. (HC) in PPM idle standard 250 Actual reading 885 ( FAIL ) (CO) in % idle standard 2.00 Actual reading 5.88 ( FAIL ) (HC ) in PPM loaded standard 250 Actual reading 124 ( PASS) (CO ) in % loaded standard 1.50 Actual reading .57 ( PASS) Is this just the wrong idle adjustment on the one barrel carb or do the figures indicate some thing more involved . Also during the test we did not know the thermostat had become stuck and by the time the test was done the truck had over heated real bad , could too hot an engine cause that bad idle reading ?? It turned out to be a real sh***y day , on the way back the truck was over heating so bad , we wound up pushing the truck the last 2 blocks just to get home . Thanks for your help .

01-02-2003, 09:09 PM	#2
JHickson6 I Love This Stuff! Join Date: May 2002 Location: Winnipeg, Manitoba, Canada Posts: 739	ahhhh thats no good! Not sure about your actual questions but before you go back again try some of those carb cleaners and emissions passing chemicals. Just a thought! __________________ My Rides 1967 C10 In Pieces for now 1985 Ford B700 SourPuss Bus - BIG BLUE 2003 Silverado CITY WORKER YELLOW!!

01-03-2003, 03:44 AM	#4
GMCPaul Senior Member Join Date: Mar 2000 Location: Rockville,In. USA Posts: 3,719	I believe your idle mixture settings are to rich, time and adjust carb with a vaccum guage and tune it up with new plugs, wires, cap, & rotor or switch to HEI distributor. I give step by step instructions on the following page of our site http://www.gmcpauls.com/Tech%20Tips1.htm You will want the section " Vacuum Gauge Use " Between doing that and Before returning get the overheating solved thats really hard on a 6cyl motor running it till it won't run, VERY easy to crack the head on them by the thermostat, install a new thermostat, and a fan shroud if yours is missing, add a mixture of 50/50 anti-freeze and water not all water even if you live where it never freezes as anti-freeze helps it to run cooler also. GMCPaul __________________ Secure Online Catalog for-GMCPauls Truck Parts Email- GMCPAULS@GMAIL.COM

01-03-2003, 11:11 AM	#5
Bowed Registered User Join Date: Oct 2002 Location: where it's hot Posts: 1,059	THANKS GMC Paul , thanks for the tech input and I will follow your advice and then see if I can get it passed . The overheating problem has been solved , has it turned out the guy I had just bought the truck from had dropped a ton of the older type radiator sealing pellets into the cooling system and had every thing from the thermostat to the heater hoses pluged up , what a mess . I hope I did not damage the motor , it did get so hot it was starting to detoniate before I was able to shut it down for good .

01-03-2003, 01:04 AM	#3
Bowed Registered User Join Date: Oct 2002 Location: where it's hot Posts: 1,059	ttt



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