Chokin Smokin

GENE · 11-22-2006, 04:00 PM

HI,I have a 1990 C-1500 w/5.7 that is driving me crazy. It has TBI.It will start up fine then the trouble begins.Once it warms up it still blows out black smoke like the choke is stuck on even though it has TBI.If I drive it down the road it dies out.I have replaced fuel pump.Somebody says map sensor,tbi itself.Can somebody please help me?

Chevy808 · 11-24-2006, 09:23 AM

Black exhaust is an indication of a rich mixture or burning of oil. Pull the codes off of your truck and see what it gives you. If I could take a wild guess

without the codes I would say your MAP sensor or plugged catalytic. Um....don't want to say bad rings.

lb23 · 10-09-2007, 12:03 PM

Black smoke = fuel
Blue smoke= Oil
White smoke = coolant

tjzz4 · 10-09-2007, 01:28 PM

Pull Codes First For Sure But I Have Also Seen An Ect (engine Coolant Temp) Sensor Do That.. If The Ecm Thinks The Engine Is Cold It Will Dump More Fuel.

Moostang · 10-09-2007, 01:45 PM

The OP hasn't been on since March (posted question last year), I hope he has gotten it fixed.

chevyguy · 10-10-2007, 05:15 PM

Temp sensor all the way.

pbouffard · 10-10-2007, 06:38 PM

coolant temp sensor fist cheap part like 11.99 also ecm can send the pulse wire too much resistance and cause too much fuel to dump, but temp sensor first

chevyguy · 10-11-2007, 03:24 PM

It runs great till it warls up. THe program is set to default for a short time to allow the motor to warm up. After that the temp sensor is the reference to tell the computer what the temp is and it defaults to -40 degrees if the temp sensor is bad.

strokin350 · 10-14-2007, 08:18 AM

it's deffinatly the CTS i just went though the exact same thing on my 92.

ryeja · 11-01-2007, 09:34 AM

Just out of curiosity, does anyone know what the ohm values should be for the CTS? I'm experiencing similar problems but would like to diagnose further. I'm reading 0.3 omhs when cold and around 0.5 ohms after about a 20 min warm up. I;m not getting any trouble codes until I unplug the sensor.

11-22-2006, 04:00 PM	#1
GENE Junior Member Join Date: Nov 2006 Posts: 2	Chokin Smokin HI,I have a 1990 C-1500 w/5.7 that is driving me crazy. It has TBI.It will start up fine then the trouble begins.Once it warms up it still blows out black smoke like the choke is stuck on even though it has TBI.If I drive it down the road it dies out.I have replaced fuel pump.Somebody says map sensor,tbi itself.Can somebody please help me? Last edited by GENE; 11-24-2006 at 05:41 AM.

11-24-2006, 09:23 AM	#2
Chevy808 Senior Member Join Date: Nov 2006 Location: Born & raised in Hawaii had to move to Salt Lake City...bummer Posts: 275	Black exhaust is an indication of a rich mixture or burning of oil. Pull the codes off of your truck and see what it gives you. If I could take a wild guess without the codes I would say your MAP sensor or plugged catalytic. Um....don't want to say bad rings. __________________ '85 Oldsmobile 442 '93 Chevy 2WD C1500 350 Silverado Extended Cab Shortbed '95 Chevy 4WD K2500 454 Silverado Extended Cab Long Bed

10-09-2007, 01:45 PM	#5
Moostang Senior Moderator Join Date: Apr 2005 Location: Cali-4 Nye-Aye? Posts: 1,378	The OP hasn't been on since March (posted question last year), I hope he has gotten it fixed. __________________ MEOW!! http://moostangproductions.com

10-10-2007, 05:15 PM	#6
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,160	Temp sensor all the way. __________________ When i die, i dont want to walk gracefully thu the pearly gates and turn in a unused body. i want to go sliding thru sideways and turn in a body that has been completely used up.

10-10-2007, 06:38 PM	#7
pbouffard Senior Member Join Date: Apr 2007 Posts: 100	coolant temp sensor fist cheap part like 11.99 also ecm can send the pulse wire too much resistance and cause too much fuel to dump, but temp sensor first __________________ IF YOU CANT FIX IT....IT MUST BE MADE IN TAIWAN

10-09-2007, 12:03 PM	#3
lb23 Full Member Join Date: Mar 2007 Posts: 22	Black smoke = fuel Blue smoke= Oil White smoke = coolant

10-09-2007, 01:28 PM	#4
tjzz4 Senior Member Join Date: Oct 2007 Posts: 234	Pull Codes First For Sure But I Have Also Seen An Ect (engine Coolant Temp) Sensor Do That.. If The Ecm Thinks The Engine Is Cold It Will Dump More Fuel.

10-11-2007, 03:24 PM	#8
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,160	It runs great till it warls up. THe program is set to default for a short time to allow the motor to warm up. After that the temp sensor is the reference to tell the computer what the temp is and it defaults to -40 degrees if the temp sensor is bad. __________________ When i die, i dont want to walk gracefully thu the pearly gates and turn in a unused body. i want to go sliding thru sideways and turn in a body that has been completely used up.

10-14-2007, 08:18 AM	#9
strokin350 Senior Member Join Date: Sep 2007 Posts: 72	it's deffinatly the CTS i just went though the exact same thing on my 92.

11-01-2007, 09:34 AM	#10
ryeja Senior Member Join Date: Apr 2007 Posts: 73	Just out of curiosity, does anyone know what the ohm values should be for the CTS? I'm experiencing similar problems but would like to diagnose further. I'm reading 0.3 omhs when cold and around 0.5 ohms after about a 20 min warm up. I;m not getting any trouble codes until I unplug the sensor.

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