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93 Skylark running rich

Tiny
KRODGERS01
  • MEMBER
  • 1993 BUICK SKYLARK
  • 6 CYL
I have a 1993 Skylark with the 3.3 liter v6. On Saturday, I replaced the spark plugs, air filter & spark plug cables as the old ones were arcing in places.

The car ran good except it over heated. Not quite into the red but enough to make the reservoir boil over when I took off the cap. Got that fixed by replacing the thermostat (195F), flushing the radiator & replacing the water heater.

I fixed a small vacuum hose that had collapsed & dry rotted that leads to a solenoid at the front drivers side. The car ran fine Sunday night & Monday morning.

Monday afternoon the car starts running really rough & you could smell how rich it was running. There is very little power & it is using a huge amount of gas as compared to before. I found another set of vacuum hoses that were breaking down. These had a larger hose that ran from a pipe that the solenoid connects to & a check valve at the other end that leads to a smaller hose. I replaced them & nothing. I also found a hose for the gas vapor canister that was off & connected it back up. Again no change.

I disconnected the O2 sensor but the check engine light never came on. I also tried disconnecting other sensors & no check engine light. This leads me to thinking it could be the computer module.

Any other thoughts would be appreciated.
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Thursday, May 19th, 2011 AT 4:04 AM

9 Replies

Tiny
KRODGERS01
  • MEMBER
  • 10 POSTS
Sorry,

at the end about the over heating that should read water pump not water heater.
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Thursday, May 19th, 2011 AT 4:06 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Probable causes of an engine running rich are as follows:

1. Excessive fuel pressure can be cause by restricted fuel return line
2. Defective Oxygen Sensors.
3. Leaking injectors and fuel pressure regulator.
4. Coolant temperature sensor out of calibration.
5. Restricted air intake system.
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Thursday, May 19th, 2011 AT 8:15 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Now that you've unplugged all the sensors, the codes won't do you much good. I suggest you clear all the codes and then drive it some more before getting the codes read and see what it setting on it's own in there.
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Thursday, May 19th, 2011 AT 11:55 AM
Tiny
KRODGERS01
  • MEMBER
  • 10 POSTS
I just disconnected 3 & then hooked them back up. They were the 02 sensor, the mass air flow sensor & the throttle position sensor.

I will take it by a shop to see if anything can be read from it.

None of these sensors caused the check engine light to come on. I would think that this could be an ECC issue.I would assume that this can be verified by trying to retrieve codes from it. I am trying to trouble shoot it but don't really have the instruments needed to test the ECC other than the poor man's way of disconnecting the sensors.

My daughter is driving it today. It will have about 40-60 miles on it when I get back to it later today.
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Thursday, May 19th, 2011 AT 4:27 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
That's not the point. You have now set false codes so the info is useless until you clear it all and start over.
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Thursday, May 19th, 2011 AT 4:33 PM
Tiny
KRODGERS01
  • MEMBER
  • 10 POSTS
I do understand your point. If I were to retrieve any codes at this time they would not be reliable until I have them cleared & drive the car more.

What if we hook up the code reader & there are no codes at all? Wouldn't that point to an ECC problem? I would fully expect to have some codes to be retrieved showing that the ECC is still performing.

I may be wrong on this line of thinking & if there are other things that could cause all of this, I would really like to go back & eliminate those possibilities.I am basically at the end of my range of expertise as far as finding obvious problems such as the vacuum leaks.
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Thursday, May 19th, 2011 AT 5:04 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Does the check engine light come on for a bulb check when the key is first turned on? If not, someone may have removed the bulb because they couldn't figure out how to make it go out. If the check engine light is working, then yes, it could be a bad ECM if no codes are found.
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Thursday, May 19th, 2011 AT 5:12 PM
Tiny
WRENCHTECH
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  • 20,761 POSTS
It's a 93. You should be able to get flash codes by jumping A and B at the ALDL connector.
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Thursday, May 19th, 2011 AT 5:13 PM
Tiny
KRODGERS01
  • MEMBER
  • 10 POSTS
The check engine light does come on for a bulb check. Our van just failed an inspection for the check engine light being out so that was 1 of the 1st things I checked.

Thanks for the information on the flash codes. I will try that when I get home.

I will post back here when I find out what it is.
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Thursday, May 19th, 2011 AT 6:11 PM

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