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89 Chevy 4x4 will not start w/o pumping the pedal
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mudman2707
New User
May 13, 2007, 7:30 PM
Post #1 of 2
(1744 views)
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89 Chevy 4x4 will not start w/o pumping the pedal
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I replaced the fuel pump last Aug, and it was starting and running great. Now it still runs great, but I have to pump the pedal 25 or more times or use starting fluid, please help, thanks.
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DanD
Veteran
/ Moderator
May 14, 2007, 5:30 AM
Post #2 of 2
(1739 views)
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Re: 89 Chevy 4x4 will not start w/o pumping the pedal
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Check the fuel pump pressure 10-15Lbs is normal for a TBI system. Also check whether the pressure holds after the engine is turned off; it will change a bit but after 15 or 20 minutes it shouldn’t have dropped anymore then a couple of pounds. The fuel pressure will eventually dissipate over time but should hold some pressure for a number of hours.
There’s a check valve in the fuel pump that is designed to hold a solid column of fuel in the lines; that’s so after sitting overnight the fuel doesn’t siphon back to the tank. If the fuel is allowed to siphon; the pump will have to refill the fuel filter, fuel line, TBI unit and then pressurize the system before the engine will start.
If the pressure(s) check out ok then you’re into checking sensor data; there might be a sensor that is still working within its perimeters and not setting a code but operating to the extreme of its range, telling the computer inaccurate information. For example if the ECT (engine coolant temperature) sensor is shorted and will not read close too ambient air temperature after the engine has completely cooled. The computer doesn’t know its dealing with a cold engine and give it extra fuel to start, like what a choke would on a carburetor engine.
Dan.
Canadian "EH"
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