1990 Chevy Suburban stalls

Tiny
JOEBEONE
  • MEMBER
  • 1990 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
When I start the car it will run for about 30 seconds then stall. Sometimes just a few seconds. I've replaced the IAC. Removed the Throttle body and cleaned all the vacuum lines and the whole throttle body.
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Thursday, May 14th, 2009 AT 8:18 PM

4 Replies

Tiny
DR LOOT
  • EXPERT
Is there an engine light on? If not, it's not a hard code therefore it will be more difficult to find the problem, but not impossible, but it sounds like either fuel pressure problems, or cold start solenoid, how does it run when it's warmed up? Or can you get warmed up? Tell me a little bit more about the patient, I want its history for the past year, and anything else you can come pertinent to the symptoms.
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Saturday, May 16th, 2009 AT 3:29 PM
Tiny
JOEBEONE
  • MEMBER
It has about 200,000 miles on it. It was working fine the day before. I tried starting it the next day and that's when the stalling started. I have not had any problems with the engine until now.
One thing, not sure if it has anything to do with it. The brake light has been on for about 4 months, brakes are good. When I release the the emergency brakes the light goes dimmer but doesn't go out.
No other lights on. Also this started about a month ago when I take it out of gear and try to back up it's acts like its in park most of the time it will snap out and move. It works better if I pull forward first then go back. It doesn't matter if its on a flat surface or not.
I've removed the throttle body and completely cleaned it. It looks like new. The IAC has been replaced and the PCV. My battery was 8 years old so I replaced that also, it died from starting the engine up so many times. As long as I've got my foot on the accellarator it runs greats once I start to coast and it gets to about 5 to 10 mph the engine light comes on because it's starting to stall. This morning I tried doing what another mechanic asked me to do by grounding the diagnostic terminal turn on the key and wait about 10 seconds for the IAC to bottom out then inplug the connector to the IAC remove the jumper and start it up again no change I even turned up the idle stop to about 1500 RPMs but after about 30 sec. The idling slows down and it stalls. I raised it up even higher and did the same thing. It's like trying to compensate for the high RPM but does it too much so the engine stalls. I have had it at Operating temperature and it still does it. I drove for about 30 min at about 50 mph but once I slowed down to turn it stalled. Wouls it have anything to do with the EGR, EGR vacuum solenoid, MAP or maybe another bad IAC.
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Saturday, May 16th, 2009 AT 5:40 PM
Tiny
DR LOOT
  • EXPERT
Sorry I had a malfunction
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Sunday, May 17th, 2009 AT 7:16 PM
Tiny
DR LOOT
  • EXPERT
Thanks for the information, now let's see if we can figure this out, have you so far perform the following diagnosis?
1. Did you check for proper operation of the thermostatic air cleaner?
2. Did you Check for proper operation of the idle air control (IAC) system?
3. I know you told me you replaced the PVC, but did you check the PVC valve for proper operation?
4. Unplug MAP sensor. EMC will substitute a default value from the sensor signal. It stall and rough idle condition is eliminated, replace sensor.
5. Did you check the EGR system for proper operation?
6. Did you check for plugged or restricted fuel lines?
7. If engine starts, but then he immediately stalls, open distributor bypass circuit. If engine then starts, and runs okay, replaced distributor pickup coil.
8. Did you check for a weak spark from ignition coil?
9. You did not mention to me if you fueled up the day before it started?
10. Did you visually check vacuum hoses for split, Kinks and proper connections as shown on vehicle Emission Control Information label located on the hood of your suburban?
11. Have you checked ignition wires for cracking, hardness and proper connection at Both distributor cap and spark plugs?
12. Ensure fuel pressure is correct and all speed ranges, also check for poor fuel quality or water contaminated fuel.
13. Did you check to make sure the TPS is not binding or sticking?
14. And make sure the ECM controlled Idle speed is correct.
15. Make sure the air conditioner is not on when attempting to diagnose.
Now I know I have giving you lots to do, but I had the same problem with my 1990 Chevy Van, after making sure all of the above was checked out, in the end it was Fuel Pump inside the tank, and so I took advantage of the situation, replace the fuel filter, and rebuilt my Throttle body (the kit was only $12) it didn't look like it needed it but when I took it apart I'm sure glad I did, the base gaskets were no good and had some pretty bad vacuum leaks which was probably causing me fuel mileage, I did that some time ago and my van is still running sweet and giving me around 20 miles to the gallon, go ahead and check the list and eliminate everything you have already done, and let me know what you come up with.
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Sunday, May 17th, 2009 AT 7:36 PM

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