96' Z-71 Fuel Problem


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Old 01-13-09, 09:26 AM
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96' Z-71 Fuel Problem

Truck started up went 250 yards and stalled. Happened a few weeks ago but started with rough idle after a few minutes, assumed water in fuel. Now will only fire with a little fuel into throttle-body. Pulled fuel lines and all clear, including fuel filter. could it be frozen in the throttle-body? Any ideas would be helpful. It's a 5.7L vortec.
 
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Old 01-13-09, 12:54 PM
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Check the fuel pressure, low pressure will not spray out of the injector properly. Just because the fuel pump can pump thru an open line does not mean it is ok. The fuel pressure regulator could be stuck open and allowing all the gas to return to the tank, causing low fuel pressure. Do you hear the pump run when you first turn on the key? If you do not hear that 3 second run, think bad pump/wiring, or a computer issue.
 
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Old 01-13-09, 01:01 PM
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pump does run. Will check pressure, hopefully it is the problem and not the ecm. thanks
 
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Old 01-13-09, 03:09 PM
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Well someone has borrowed my tester and liked it more than I did. pushed in on the check valve for testing and got a 2" spout of fuel, dont know if that helps or not but didn't seem like much pressure. Ideas?
 
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Old 01-13-09, 04:46 PM
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As you may already know, these trucks are notorious for fuel pump and regulator failures, which your symptoms do indicate.

A test for pressure and bleed down is required. Many auto parts stores will loan you a pressure tester. Check the pressure then check bleed down over an hour.
 
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Old 01-14-09, 03:30 PM
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You definitely need to check the fuel pressure with a gauge. If the PSI is 45-50 while cranking (or less) then you need a new fuel pump. That style Vortec needs about +55 PSI to start.
 
 

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