Go Back   DIY Chatroom Home Improvement Forum > Do It Yourself > Automotive Repairs

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 10-06-2009, 02:36 PM   #1
Newbie
 
Join Date: Jul 2008
Posts: 29
Share |
Default

94 chevy 4x4 truck problem


94 chevy truck 5 speed, vortec 4.3 v6 engine.

truck is running rich, has new air filter, plugs.
What can be causing this ???

tecate1987 is offline   Reply With Quote
Old 10-06-2009, 07:00 PM   #2
Member
 
Join Date: Nov 2008
Posts: 187
Default

94 chevy 4x4 truck problem


Thermostat stuck open or a bad computer temp sensor could cause it to run rich.

Gary

Gary_602z is offline   Reply With Quote
Old 10-06-2009, 07:44 PM   #3
Newbie
 
Join Date: Jul 2008
Posts: 29
Default

94 chevy 4x4 truck problem


it happens pretty much from start up.
is the temp sensor the same part as this on ebay.? item #250355290617

temp control ?
tecate1987 is offline   Reply With Quote
Old 10-06-2009, 09:45 PM   #4
Member
 
Join Date: Nov 2008
Posts: 187
Default

94 chevy 4x4 truck problem


Quote:
Originally Posted by tecate1987 View Post
it happens pretty much from start up.
is the temp sensor the same part as this on ebay.? item #250355290617

temp control ?
No that is an A/C temp control.
I was talking about the Computer temp sensor that send the engine temp to the computer. There is also a sensor for your temp guage or light which would be different

Gary

Have you checked for any codes?
Gary_602z is offline   Reply With Quote
Old 10-07-2009, 05:35 AM   #5
Newbie
 
Join Date: Oct 2009
Posts: 3
Default

94 chevy 4x4 truck problem


another thing you might try to check is, pull the engine oil dipstick out and smell the oil on it, if it smells like gasoline, you could have a fuel injector or fuel injector line problem, those vortec engines have plastic lines inside the intake plenum that sometimes will crack, and make the engine run extremely rich, and dump fuel right down into the crankcase and evantually ruin the engine., i would also check for codes , it is very possible it could just be a coolant temp sensor, or even a different problem, i've seen bad vacuum lines to the map sensor also, although i cant think right off the top of my head if that particular one has a vacuum hose or if it is directly mounted into a vacuum port. 20 plus year ase master mechanic, just thought i'd throw some quick ideas at ya.
mspeckhem is offline   Reply With Quote
Old 10-07-2009, 09:34 AM   #6
(the original)
 
Join Date: Jun 2007
Location: long beach, ms
Posts: 520
Default

94 chevy 4x4 truck problem


Check the fuel pressure and pull codes. Could just be the fuel pressure regulator. If so, the only code it would throw would probably be one indicating the O2 sensor is detecting a rich condition.
ratherbefishin' is offline   Reply With Quote
Old 10-07-2009, 02:17 PM   #7
Newbie
 
Join Date: Jul 2008
Posts: 29
Default

94 chevy 4x4 truck problem


I am going to see if my coder will read with this year truck.
If the weather clears up some today. I will also check the oil smell.
thanks for the help, I will reply with updates.
tecate1987 is offline   Reply With Quote
Old 10-07-2009, 11:32 PM   #8
Oldguy
 
Rehabber's Avatar
 
Join Date: Dec 2005
Location: Calif (the left coast)
Posts: 498
Default

94 chevy 4x4 truck problem


VERY high possibility of bad fuel pressure regulator. The diaphram pops and leaks fuel into the intake manifold. A pressure check may not determine this leakage.
__________________
If you think you can, or if you think you can't, you're probably right.

ASE certified master auto tech, Retired.
Rehabber is offline   Reply With Quote
Old 10-08-2009, 09:22 AM   #9
Member
 
47_47's Avatar
 
Join Date: Sep 2007
Location: Springville, NY
Posts: 1,432
Default

94 chevy 4x4 truck problem


A fuel pressure regulator will fail in one of two ways. Either cause high fuel pressure (measure with a gauge) or bypass internally as Rehabber stated. To check for a bypass, remove the vacuum line from the regulator and check for fuel.

I'm leaning toward a bad ECT or thermostat.
__________________
What we've got here is... failure to communicate. Some men you just can't reach. So you get what we had here last week, which is the way he wants it... well, he gets it.
47_47 is offline   Reply With Quote
Old 10-08-2009, 11:14 AM   #10
Resident Computer Guru
 
Join Date: Jul 2009
Location: NOVA
Posts: 28
Default

94 chevy 4x4 truck problem


Is it showing a code? Please pull the code (or go to advanced auto/autozone) to have them pull it.

Alot of people jumping to some serious conclusions on this thread. My thoughts (in this order):

1> O2 sensor
2> FPR
3> Temp sensor
4> Dinosaur attack caused fuel problem
newbsauce is offline   Reply With Quote
Old 10-08-2009, 12:15 PM   #11
Member
 
47_47's Avatar
 
Join Date: Sep 2007
Location: Springville, NY
Posts: 1,432
Default

94 chevy 4x4 truck problem


This truck has OBD. I think Autozone can read only OBDII codes. The OP did not state if the SES light is on, usually that is the first complaint stated. To read the codes on this truck, turn the key on and jumper pins A & B of the ALDL. You will count the flashes of the SES light. You always will read one flash, a brief pause then two more flashes (code 12, no RPM and is normal). The MIL will flash this code a total of three times, then proceed to the next code.

http://www.troublecodes.net/GM/

Engine control diagnosis starts with retrieving codes, undertanding what it takes to set the fault, following trouble trees and knowing what normal readings are. It does NOT mean read a code and hang a part.

I'd start by getting a scanner, measure and compare the ECT readings. If you watch the scanner, you will also know when the tstat opens at around 190. Good luck.
__________________
What we've got here is... failure to communicate. Some men you just can't reach. So you get what we had here last week, which is the way he wants it... well, he gets it.

Last edited by 47_47; 10-08-2009 at 12:24 PM.
47_47 is offline   Reply With Quote
Old 10-08-2009, 12:17 PM   #12
Resident Computer Guru
 
Join Date: Jul 2009
Location: NOVA
Posts: 28
Default

94 chevy 4x4 truck problem


Quote:
Originally Posted by 47_47 View Post
This truck has OBD. I think Autozone can read only OBDII codes. The OP did not state if the SES light is on, usually that is the first complaint stated. To read the codes on this truck, turn the key on and jumper pins A & B of the ALDL. You will count the flashes of the SES light. You always will read one flash, a brief pause then two more flashes (code 12, no RPM and is normal). The MIL will flash this code a total of three time, then proceed to the next code.

http://www.troublecodes.net/GM/

Engine control diagnosis starts with retrieving codes, undertanding what it takes to set the fault, following trouble trees and knowing what normal readings are. It does NOT mean read a code and hang a part.

I'd start by getting a scanner, measure and compare the ECT readings. If you watch the scanner, you will also know when the tstat opens at around 190. Good luck.
Good information. Not sure about the setup of your car, but rather then using the scanner, I simply grab my upper radiator hose. There is a huge temperature difference when the Tstat opens Granted, I know my cars normal operating temp, and trust my gauge.
newbsauce is offline   Reply With Quote
Old 10-08-2009, 12:57 PM   #13
I have gas!
 
Clutchcargo's Avatar
 
Join Date: Mar 2007
Location: Massachusetts
Posts: 1,770
Default

94 chevy 4x4 truck problem


How do you know it's running rich?
Is the check engine light on?
Pull the codes for a start.
My guess would be the O2 sensor.
__________________
I tear things down and build them up.
Clutchcargo is offline   Reply With Quote
Old 10-08-2009, 01:07 PM   #14
Member
 
47_47's Avatar
 
Join Date: Sep 2007
Location: Springville, NY
Posts: 1,432
Default

94 chevy 4x4 truck problem


Quote:
Originally Posted by newbsauce View Post
Good information. Not sure about the setup of your car, but rather then using the scanner, I simply grab my upper radiator hose. There is a huge temperature difference when the Tstat opens Granted, I know my cars normal operating temp, and trust my gauge.
Yes this would tell if the tstat is opening, but will not give any information about the coolant temp the computer senses vs the actual engine temp. BTW this truck should have 2 coolant sensors, one for the gauge and the other for the ECM.

To the OP, with a scanner look at the integrator. Ideally it is at 128. With a rich running engine, the integrator will go down. Usually down around 100 I start looking for rich conditions.
__________________
What we've got here is... failure to communicate. Some men you just can't reach. So you get what we had here last week, which is the way he wants it... well, he gets it.
47_47 is offline   Reply With Quote
Old 10-09-2009, 02:44 PM   #15
Newbie
 
Join Date: Jul 2008
Posts: 29
Default

94 chevy 4x4 truck problem


ok, I havent checked must due to cold and wet weather.
But,

there is not check engine light on, it does work cuz it lights before starting engine. It has obd, and my scanner is obdII, I cant plug that in.
Also, truck is plow truck and not street legal to take to autozone.
Oil smells fine. going to try to check thermostat for sticking, and also pull vacuum line off fpr to check for extra fuel.
thanks for all the help so far, if I run into more info I will provide and any other ideas are appreciated, thanks.

tecate1987 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
75 year chimney leak problem mstanleyg Building & Construction 10 03-30-2010 12:38 PM
Problem with fan coil unit/hydronic system. flood1911 HVAC 2 09-05-2008 04:57 PM
Stymied by window leakage problem. Matth3w General DIY Discussions 5 06-11-2008 06:26 PM
Door -Storm Door problem bassman Building & Construction 2 01-17-2007 03:16 PM
Post-Tension Slab Problem Advice/Help Mike McBride Building & Construction 2 01-09-2007 01:51 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.