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Canuck Tech
Canuck Tech, Auto Service Technician
Category: Car
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Experience:  Red Seal Journeyman Technician, 20 Years experience
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GMC 1500: 94 GMC 5.7L. Truck stalled while driving normally

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94 GMC 5.7L. Truck stalled while driving normally and would only start if I gave it gas while starting. Then it ran rough putting out blue smoke. I have changed out the fuel pump. fuel filter, fuel pressure control, injectors, idle control, throttle position indicator, MAP sensor, EGR, fuel relay, ignition control module, rotor cap, rotor, wires, plugs and engine control computer. There are no vacuum leaks that I can find but the truck still does not start normally unless I depress the accelerator all the way down. Then it starts and runs very rough. When I get it down to idle it puts out blue black smoke out the tail pipe. I have no idea what is going on.
Hi there - I would try a new engine coolant temperature sensor.(ECT) This sensor has a serious influence as to how much fuel goes in to the engine. Check the connector closely as well - sometimes there is some corrosion. Also, these trucks are known for gasket leaks between the throttle body and the intake manifold, which also fits the symptoms
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The blue smoke is a bit troublesome, but see what happens once you get fuel delivery under control. Do you have access to a scan tool? This would help immeasurably.

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