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Discussion Starter #21
Just wrapped up testing. This just gets weirder and weirder.

1.The car did not build up any pressure when in accessory while cold(what I mean by cold is that it hadn't been on in a while). I tried multiple times.

2.With the car on, it was reading about 45 psi.

3.After turning off the car, it consistently dropped about 5psi every 30 min. Tried to start it after 2.5 hours at 20 psi and it started right up. It has never done that.

This car is throwing me for a loop, that's for sure.
 

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2004 chevy trailblazer_lt
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First off, you first needed to turn the key to the ON position, not the Accessory position. The fuel pump does not engage when the key is in the Accessory position.

OK, it looks like you have a fuel pump going bad. The fuel pressure should be at least 55 psi with the Key ON, Engine OFF. I would imagine it should be at least 50 psi when the engine is running.

Now to address the fuel pressure bleed off. It could be due to a faulty fuel pump (which it appears you have). Or, it could be due to a faulty fuel pressure regulator (ruptured diaphragm), one or more fuel injectors not seating properly, or, there is a leak in a fuel line or at a place where there is a fuel line joint.

My recommendation is to first repeat the fuel pressure test doing the Key ON, Engine OFF test first. Remember Key ON is not the same as turning the ignition switch to the Accessory position. If the pressure does not read at least 55 psi, then you'll need to get the fuel pump replaced. If you are going to replace the fuel pump yourself, I strongly recommend replacing the fuel pump assembly with either a Delphi fuel pump, or an ACDelco fuel pump. Do not cheap out on the fuel pump as less expensive, no name fuel pumps are less expensive for a reason - they are not made with the same quality parts and procedures that the Delphi and ACDelco ones are. I just read where a gentleman on another forum replaced the fuel pump using an Ultra Power fuel pump that cost about half of what a Delphi or ACDelco pump cost. Well, it lasted only 3 days and less than 500 miles and then died.

After replacing the fuel pump, repeat the fuel pressure test and see if the fuel pressure bleeds down as it did today/yesterday for you. If it doesn't the old fuel pump was the cause of that too. If is does bleed down, then look at the fuel pressure regulator, fuel injectors, or a bad fuel line joint as the cause. If you narrow it down to one or more fuel injectors not seating properly, I would first pour two 20 ounce bottles of Techron Complete into the gas tank and attempt to drive the fuel injectors clean. If that doesn't work then you can think about tracking down and replacing the leaky fuel injector(s).

Good Luck!
 

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Discussion Starter #23
Thanks for the response. That's my bad with the wording, I have a habit of calling "on" as accessory. For good measure, I did test it again to find the same result.

The main reason I created this post was that back in august I replaced the pump with a new Delphi pump and then this problem happened so I got another new Delphi pump and the problem still persisted so that's why I got stumped....unless I got two bad Delphi pumps in a row. But odds would say that's slim.
 

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2003 chevy trailblazer_ltz
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Before I installed a THIRD fuel pump, I would test for voltage (as close to the pump as I could conveniently get) and I'd also want to know how much amperage the pump was drawing.

An electric pump doesn't pump well if it's starving for electrical power. A pump that doesn't prime is likely being driven by a faulty electrical circuit--failed ECM, failed wire harness, failed fuel pump relay.

I don't remember reading about you replacing the fuel filter. A plugging filter can drop system pressure.
 

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Discussion Starter #25
Good idea, I am not too sure where ill be able to get a reading without dropping the thing again. Unless I misunderstood, there is not an external filter for the +06' model(which is what I have).
 
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