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Fuel Pressure help!

This is a discussion on Fuel Pressure help! within the General Help forums, part of the LSx Technical Help Section category; Ok, I got a 98' and I know the fuel pressure is supposed to be around 58-60 psi. But it ...

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    Fuel Pressure help!

    Ok, I got a 98' and I know the fuel pressure is supposed to be around 58-60 psi. But it fluctuates based on nothing I can figure out. Sometimes it runs at 50 and sometimes 58. Is this normal I have even seen it as low as 45. It seems to stay at whatever pressure it cranks at for a while, and sometimes increases to 60. I have no clue as to what is going on. I have replaced the fuel pump and since regulator came with it, it was changed too. Is there anything else that could be wrong? Any help would be appreciated. Thanks.

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    Senior Member JayTA98's Avatar
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    There are a few things that could be happenning. One question: are these pressures with the car running or just priming? If you turn the key in the on position, what's the pressure you get until it stops priming? and does it holds the pressure once the pump stops priming? If the pressure doesn't hold after the pump finishes priming you have a possible cut or hole in the fuel tube inside the tank. I installed a racetronix fuel pump recently and after I was done priming the fuel pressure will drop to zero. When I pulled the pump out there was a pin hole in the fuel tube. I'm still waiting for the replacement to arrive (if racetronix decides to send it) but i was able to use some R9 fuel hose. Now R9 hose is not designed to be submerge in fuel but it will last until the other fuel tube gets here. If you can find R10 rating hose then you are good to go.

    When you put the fuel pump back in be very careful of rubbing the fuel tube around the edges of the tank. The tank edges are kinda sharp can create a slight cut that can leak or cause a leak down the road.

    Let us know.

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    These are the pressures it primes at. It holds pressure after priming also so I dont think that is my problem. Its just that the pressure it holds is random between 45 and 60psi.

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    Senior Member JayTA98's Avatar
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    Did you change the fuel filter? Can you check the voltage at the pump? other than having a bad pump.

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    Moderator Cutlass's Avatar
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    I think 98s have a fuel pressure regulator on the fuel rail that has a vacuum line going to it. The engine vacuum applied to the regulator changes the fuel pressure.

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    Senior Member JayTA98's Avatar
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    Quote Originally Posted by Cutlass View Post
    I think 98s have a fuel pressure regulator on the fuel rail that has a vacuum line going to it. The engine vacuum applied to the regulator changes the fuel pressure.
    If you mean the silver round looking regulator in the middle tube of the fuel rail, the answer is no, it doesn't have a vaccum tube on 98's. At least doesn't.

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    I have changed the fuel filter and like I said I changed the fuel pump and it kept the exact same problem. But I didn't think about the voltage does it need to be checked at the fuse? Or on top of the tank?

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    Senior Member JayTA98's Avatar
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    I will check it at the top of the tank. just to rule out that you might have a voltage issue.

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