Question about 2003 Chevrolet Impala

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I CANT GET MY 05 impala to hold fuel pressure a regulator with key on goes up 50-60 when key is turned on but drops right down have replaced fuel filter,pump,injectors and regulator still no help and has cly 1 miss fire code

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  • carmanat Nov 05, 2009

    when I turn key goes to 50-60 It starts to drop right down to 40-30 then slower after that till gone but within a min or so way down

  • carmanat Nov 06, 2009

    Tried that no leaks at injectors when fuel rail is pulled out. I noticed that a couple clips on fuel line back by tank are broke they had a twist tie on one and silicone on couple others could they leak pressure but not gas.

  • carmanat Nov 09, 2009

    fuel seems to hold around 50 for awhile with switch on now then slowly drops into the 40s. Cant get rid of no.1 cyl missfire comp is 130 someone said maybe intake gasket leaking anyway to check this.

  • Chris May 11, 2010

    How long does it take for pressure to drop off ? how much pressure is lost, all of it??



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Sounds like #1 injector is stuck open
unbolt the fule rail lift it up and turn the key to run and see if that injector is leaking

Posted on Nov 06, 2009

  • Kevin Rahme Nov 06, 2009

    no it would leak fuel

    ok try pinching off the return line and see if it holds pressure

    let me know



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I found out that my 2001 blazer had no gasket in it replace them but still smelling gas and it making noise what ekse could it be I need help

If you are smelling gas it is because you are getting excess fuel somewhere
Most likely it is the fuel injection unit or the fuel pressure regulator inside the intake plenium on top of the motor there is a shrader valve on top on drivers side of air intake on the fuel lines have someone pressure test the fuel pressure when you turn the key on and off three or more times to prime the pressure then turn the key off and watch the gauge while priming pressure the pressure should be 60 psi then after priming pressure and turning key off pressure should drop to 55psi and hold that pressure for 5 minutes minimum if it does not hold that pressure and starts dropping to zero your fuel injection unit and pressure regulator are leaking and dumping excess gas into the air intake plenium and it is easier to replace the injection unit and the pressure regulator as you can buy them cheaper combined a new injection unit comes with the new fuel pressure regulator
And if they are leaking gasoline after a failed pressure test that is why you are smelling gasoline
Have it pressure tested right away as if this indeed is the cause the excess fuel could combust at one point and cause a lot more damage
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My 97 chevy blazer starts fine after sitting overnight. However, each subsequent stop/start after that it gets harder to start. It turns over but won't fire up or stalls briefly after? It has new fuel...

check the fuel pressure. I will put money on a fuel pressure regulator leaking. The regulator is attached to the back of the CPI unit under the intake plenum. Fuel pressure should be 55-60 psi roughly and hold for a couple of hours. If pressure drops the first thing I would look at is the regulator.

You can also try this. Instead of trying to start the vehicle right away. turn the key to the run position, wait 5 seconds, then turn the key off. Repeat this a few times, then start the vehicle. If it starts right up than for sure you have a fuel issue and checking fuel pressure will be the next step.

The fuel pressure port is located on the back of the engine on the drivers side near the distributor.

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Try taking the vacuum hose off the regulator and see if its leaking there. If not, the only way to isolate it woud be to block or pinch closed the fuel line.

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1 Answer

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It sounds like your loosing your fuel pressure prim. There is a check valve at the fuel pump and when it goes bad, the fuel pump unit needs to be replaced and that will also address your gas gauge issues. If yo go to Auto Zone you can buy a replacement fuel pump and they will have the step by step instructions for you to replace the fuel pump. I'll give you a hint, remove the Bed from the rails since there is only about 8 bolts holding it down. This is easier then dropping the gas tank to get to the fuel pump in the tank. Also lone out a fuel pressure gauge and check the fuel pressure at the Shredder valve and do a pressure drop, once you have the proper fuel pressure 60 to 65psi, see how long it will take for the fuel system to drop. If it drops quick, time to replace the fuel pump and replace the fuel filter too since your doing all this work. Good luck friend. Keep me posted if you have any other questions. 

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Do you have the fuel tester hooked the in the overgrown air valve on the fuel rail in the back of the engine? Or do you have the fuel line unhooked in the back and hooked to the pressure pump? You want the fuel pressure to be in that 60 lb range so if you are hooked into the pressure valve on the fuel rail allowing fuel to go through, then I am betting it is the fuel pressure regulator. To get to that, you have to take the throttle body off and take the plastic plenum that covers the injector packs. On the back of the mount where your six pack of injectors are sits the pressure regulator. If it is faulty then it is dumping fuel instead of holding the pressure like it should.
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