1998 GMC Yukon rough running engine

Tiny
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  • 1998 GMC YUKON
Engine Performance problem
1998 GMC Yukon V8 Four Wheel Drive Automatic

after the engine has been running 15 to 20 minutes it starts to run rough and will almost kill if sitting at a stoplight. Last year we replaced the fuel pump, filter, relay switch, plugs and wires. It starts and runs GREAT for the first 10 to 15 minutes, then she geats weird.
Monday, September 21st, 2009 AT 6:42 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Has the check engine light ever come on? Have you checked fuel pump pressure even though it was replaced a year ago? Here is a how to for checking pressure.

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

Finally, my other concerns would be a bad EGR valve or a plugged catylatic converter. Check both of them and let me know what you find.

Joe
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Monday, September 21st, 2009 AT 10:12 PM
Tiny
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Check engine light came on 1 year ago and I replaced the O2 sensors (2), recently the "Service Engine Soon" light came on. I replaced the cap and rotar and that went off. I did discover that a recepter hole for the one of the screws that holds the cap on was broken. I managed to secure the cap in place using plastic weld. I have not check the pressure in the fuel line, and I will look at the converter and the EGR valve and let you know.
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Tuesday, September 22nd, 2009 AT 10:24 AM
Tiny
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Is the distributor cap okay now? That could cause the problem you described.
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Tuesday, September 22nd, 2009 AT 10:32 AM

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