Mechanics

NOW IT WONT START AT ALL.. HERE IS WHAT I HAVE FOR ANY IDEAS?

2000 Oldsmobile Bravada • 6 cylinder AWD Automatic • 127,000 miles

I recently replaced a fuel pump on my bravada. My gas tank has a leak so I replaced the tank with a used one from a junk yard.

When lowering the leaky tank it slipped and fell breaking a post from my fuel pump. I decided to use the fuel pump that came with the tank to save money. TUrning the key, I can hear the pump kicking on and off but not starting the car. Now my car kicks a P0452 code. I notice my pressure sensor could use replacing. But would that cause it not to start?

ALSO I noticed in the bottom of the used tank I got a little bulb looking thing rolling around, I removed it. I assume it connects to the vent on the gas tank. WOULD that be a reason for it not to start? Lastly I read on another post where someone was having my issue and a response was is your does your battery constantly die. Could the two be related? Even jumping my car for a half hour, if the cables are off it dies very fast. Any help appreciated.

I assume it COULD be a bad pump but hoping not. Thanks in advance
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Jf781981
July 18, 2012.




The P0452 is a low fuel tank pressure code. If you look under the hood, you should be able to find a pressure test port near the center of the intake where the fuel lines enter. It should look like a valve stem cap on a tire. If you can borrow a fuel pressure gauge and attach it here, you will be able to take a manual pressure reading. I will have to look up the specs for sure, but I believe it should be between 50 and 60 psi. If fuel pressure is too low the vehicle will not start. The injectors on the 4.3 vortec are pressure activated and wont open even if the fuel pressure is one or two psi lower than spec. Considering that its a used fuel pump on what already is a sensitive fuel system, I would verify pressure before wasting time on anyother tests.

Marv-Ellis
Jul 18, 2012.
When checking the pressure should the vehicle be in the on position or key off
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Tiny
Jf781981
Jul 18, 2012.
Key on cranking the engine so that it has enough time to build fuel pressure.

Marv-Ellis
Jul 18, 2012.
Just to add to this one that code has nothing to with fuel pressure for the engine running. Thats the pressure sensor that measures the vacuum of the fuel tank not pressure but vacuum. Its used to see if there is a leak in the evap system its basicially a map sensor and is used as a map sensor on some of the gm cars. So did you have the code before you changed the fuel pump?

Saturntech9
Jul 18, 2012.
No I didnt. Unfortunately it could be days before I can do something on a fuel pressure gage. I dont have one, and the only place that does loan out charges up front for them first so it will be a couple days before I get paid to rent a gage. Also what is that little thing I was describing in the tank? I was bulb shaped

Tiny
Jf781981
Jul 18, 2012.
Iam sorry I stuck my foot in my mouth reading the way you jumped from code P0452 to checking the fuel pressure didnt catch what you were meaning and talking about with checking the fuel pressure. DIDnt read the very end where it said I wouldnt waste my time with other tests before making there was the proper fuel pressure. It was kinda all blended together in the begining. Again iam truly sorry for the mix up.I always try to make sure are users get the most actuarte help I can give them.

Saturntech9
Jul 18, 2012.
Hard to say what the bulb shaped object is. It is most likeley part of a broken vent or pressure control valve, but the possibilities are endless without seeing the object or knowing the dimensions of it.

Marv-Ellis
Jul 18, 2012.
Some cars use roll over valves that keep the gas from leaking out if the car were to roll over. May or may not be what you were seeing. Iam going to give you back to Marv-Ellis. Who iam again truly sorry for the mix up.

Saturntech9
Jul 18, 2012.
As far as the P0452, the fuel tank pressure sensor is a small black sensor with a three wire connector mounted into a rubber grommet on the fuel pump housing. It is easily removed by GENTLY prying straight upward on the sensor. If you didn't have the code before, you can simply swap your old sensor in its place. Make sure to put a little lube on it before reinstalling so you don't damage the sealing grommet ( preferably silicon dielectric grease)

Marv-Ellis
Jul 18, 2012.
No prob saturntech. Hope I was of some help

Marv-Ellis
Jul 18, 2012.

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