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94' CPI Fuel Pressure Problems.

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Old 04-21-2011, 05:06 PM
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Default 94' CPI Fuel Pressure Problems.

Currently working on my dads 94 s10 Blazer, right now it cranks but won't start. It does start if you dump some gas into the intake but dies out once that fuel is spent. The Fuel Pressure is way low with the key in the on position it stays steady at 20psi, There are no visible leaks around the spider or on any of the fuel lines.

So far we have installed a new fuel filter, fuel pump, and fuel Pressure regulator and not sure where to go from here.

Also much thanks to swartlkk for the speedy answer to my earlier vacuum question.
 
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Old 04-22-2011, 01:01 AM
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Sounds like you got a fuel pressure gauge. Are you checking pressure at the pump or schrader valve? I would check the pressure from the pump. Some fuel pressure gauges come with the kit to check pressure coming from the pump.
 
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Old 04-22-2011, 10:33 AM
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Originally Posted by Cidium
Sounds like you got a fuel pressure gauge. Are you checking pressure at the pump or schrader valve? I would check the pressure from the pump. Some fuel pressure gauges come with the kit to check pressure coming from the pump.

I am testing at the valve, my fuel pressure gauge only has the screw on end to attach to the valve.

I am wondering if there is a bad electrical connection to the pump, if it can't get all the juice it needs it cant build the pressure. My father installed it not me so I'll have to double check the wiring.

Edit: As soon as it hits the 20 psi you can hear the fuel relay click
 

Last edited by MuddyWater87; 04-22-2011 at 04:36 PM.
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Old 04-22-2011, 08:27 PM
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When you replaced the pump did you replace the 2 inches of fuel line running from the pump to the sending unit? Could be a bad pump or the wrong pump. Also when ever I have fuel problems I just assume it's the spider because they suck and always break.
 
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Old 04-22-2011, 11:25 PM
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Edit: As soon as it hits the 20 psi you can hear the fuel relay click

If you are testing the key on position then the pump runs for a couple of seconds and shuts off. I would either check to see what pressure your pump is outputting or run down a second pressure gauge to confirm yours is in spec.
 
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Old 04-23-2011, 06:10 PM
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Welp, I was able to rig up the pressure gauge directly to the pump and applied power directly to it, Still 20 psi. So went down to the auto store and picked up another pump, threw it in the sending unit rigged everything up and BAM over 90 psi. I guess the pressure should even out once everything is hooked up properly.

I guess the pump was either defective or the wrong one all together, at least now we are well on our way to getting this thing back on the road.

Thanks for the responses guys!
 
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Old 04-24-2011, 07:01 PM
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I like happy endings
 
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Old 04-25-2011, 09:57 PM
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Sounds like you got the first pump for a code Z engine instead of a W
 
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