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Ask Don Knight Your Own Question
Don Knight
Don Knight, ASE Certified Technician
Category: GMC
Satisfied Customers: 1736
Experience:  Over 40 years working on all makes and models.
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99 GMC Suburban no start dumping fuel washing down plugs

Customer Question

99 GMC Suburban no start dumping fuel washing down plugs firing ,no codes replaced key and lock cylinder ,try to start when you let key go back
Submitted: 1 year ago.
Category: GMC
Expert:  Don Knight replied 1 year ago.
The most common cause for dumping fuel is a defective coolant temperature sensor.When the sensor fails the computer thinks it is -40 degrees and adds fuel to help the engine to start.If you have a scan tool that can read a data stream look at the engine coolant temperature sensor and see what it is reading.If it is reading -40 degrees change the sensor and that should correct your problem.
Customer: replied 1 year ago.
I put the coolant temperature switch on add coolant still the same problem won't start when you release the key it stumble like it's trying to catch it has about 63 lbs. Of fuel pressure
Expert:  Don Knight replied 1 year ago.
I need to know which fuel system you have.Do you have the injectors in the throttle body or does each cylinder have its own injector?The first one is known as CSI and the other is the SFI.Please let me know which system you have and we can go from there.I will be on and off this site most of today.
Customer: replied 1 year ago.
It has the spider type csi with the big plug on top
Expert:  Don Knight replied 1 year ago.
You have another common problem with this type of injector system.The injectors get stuck open and thus your fuel problem.You will need to remove the intake manifold to get to the "spider".Once you get the manifold off you should see a "puddle" of fuel on the side that has the defective injector.Most parts houses sell the spider so you dont need to go to the dealer.Please let me know if you need more assistance and have a great 4th,Don
Expert:  Don Knight replied 1 year ago.
Do you need any more assistance?