'90 GMC 5.7 Liter Throttle Body Injection Flooding

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CraigE

Guest
#1
I have a 1990 GMC Vandura 3500 one ton with a 350 engine Auto Trans, Throttle body injection. What would cause too much fuel to be dumped from the injectors. This is spraying so much that I need to unplug the injectors to get it to start. Otherwise raw fuel is fouling the plugs. I have swapped the throttle body ( both injectors and regulator ) with a known good unit and the same thing occurs. The van went about 1 mile them so much black smoke and no start again due to too much fuel.

What else can be causing all this fuel. At start I can see the injectors pulse spray. It is not a constant stream. And the flow stops when the injector is unplugged. The unit I swapped in also verifys that it is not the injectors. Any help is appreciated. This is a van that the scout troop uses and we really do not want a tow bill since it is a dually. Thanks CRAIG
 

Gus

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#2
Sure the wire harness to the injector(s) isn't grounded? One side is hot the other side is pulsed by the VCM, but if the wire from the VCM is grounded, will flood the TB......Have seen the area where the air cleaner mounts, cut through these wires and ground them...
 

Transman

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#3
We had one like that in the shop that turned out to be the coolant sensor was shorted out. Do you have any codes? Are you able to see the data stream? You may have damaged the o2 sensor from too much raw fuel too, don't be surprised if you have to change it when you find the problem. Post back with more info, Transman
 

Scott

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#4
Check the vacume to the MAP sensor , on the passanger side of the throttle body . Map is the big player in fuel control . There will be a vacume line to it , and a three wire connector , right next to the egr solenoid , which has a two wire connector and two vacume hoses , one the same bracket .
 
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CRaig

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#5
The only codes set now are a 12 and 15. I do not believe it ran long enough since the problem to set any codes. If I unplug the MAP or coolant sensor is that a valid test? Thanks CRAIG
 
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CraigE

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#6
Well Like I said a code 15 was set. Unfortunately I did not look at the code chart but thought I remembered it as an Oxygen sensor code. It is a coolant temp code and that was the problem. A $16 sensor and it is fixed. A little knowledge is great. Thanks for getting me going in the right direction. CRAIG