1993 GMC Yukon starting and hesitation

MARK PEARCE

MEMBER
1993 GMC YUKON

Engine Mechanical problem
1993 GMC Yukon V8 Four Wheel Drive Automatic

Just bought a 93 Yukon with a 350. We changed the altenator and shorly thereafter, sometimes it is hard to start. It smeels of gas when this happens. It will start if you hold the pedal all the way down. Once it starts, it runs fine. Occassionally, it will hesitate when trying to accelerate as if its getting to much gas or not enough. Any ideas?

4 Replies

MASTERTECHTIM

MECHANIC
4,750 POSTS

93 has a tbi injector. I would first look at the injectors under the air cleaner and turn key to run position and see if any fuel leaks from the injectors, if it does then you will need to replace the injectors.

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Friday, October 31st, 2008 AT 2:14 PM

MARK PEARCE

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3 POSTS

Thanks. I won't be able to check it for a few days as I am out of town. I will let you know what I find.

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Friday, October 31st, 2008 AT 7:01 PM

MARK PEARCE

MEMBER
3 POSTS

I don't see any fuel leaking from the injectors with the key in the run position, but there does seem to be quite a bit of fuel comng out of the injectors on idle. There is definitely black smoke from th exhaust on idle, indicating a rich mixture. My thought is to replace the regulator and the injectors. Does that sound like the best course, or should I check something else before just starting to replace parts?

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Monday, November 3rd, 2008 AT 9:13 PM

MASTERTECHTIM

MECHANIC
4,750 POSTS

Definitely not. I would be leaning towards a bad coolant temp sensor or a faulty o2 sensor that reads full lean, this would tell the computer it needs to be full rich trying to get the o2 sensor to switch and if the o2 is stuck on lean then the computer gives as much fuel as it can to try to make the o2 sensor read rich.(Does that make sense) also check the computer grounds which are located on the thermostat housing stud. Clean and retighten those grounds paying special attention to the wire at the end near the eyelt, to make sure its not broken inside the insulation.

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Tuesday, November 4th, 2008 AT 5:16 AM