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I need your input on my fuel problem

This is a discussion on I need your input on my fuel problem within the General Help forums, part of the LSx Technical Help Section category; My dad brought my car to the dealership today and surprisingly got some free advice for what could be wrong ...

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    Rice Hungry GottaHaveLS1's Avatar
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    I need your input on my fuel problem

    My dad brought my car to the dealership today and surprisingly got some free advice for what could be wrong with my car. I'm getting 25 psi at the rail and i've already replaced the fuel pump and fuel filter... so we're trying to narrow it down more and finally fix this sun'bitch.

    The tech at the dealership said that LS1 f bodies don't come with Fuel pressure regulators, but with a fuel pressure sensor that's attached to the top of the tank. He said if it was malfunctioning, it could limit fuel pressure. He said another possibility could be the fuel tank vent selenoid malfunctioning. do any of you guys know anything about these two devices? any advice is much appreciated.

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    Member 666ws6's Avatar
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    I'm no expert, but there is a lot online here so do a search. Assuming you checked your filter, you might be looking at dropping your tank to check the pump. I believe the regulator is in the tank. When do you see 25 psi, the entire time?

    I thought I needed a new pump awhile back, but turned out to be a problem with my MAF making me lean at WOT.

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    Member Goldcuffs's Avatar
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    Unscrew the filter and check pressure there.Then you will know if it's something in the tank or up at the rail. If you suspect a vent solenoid (which I doubt it is) just unscrew the gas cap and see if you gain pressure. Does the car run? (It shouldn't on 25 psi)

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    Senior Member bills98ta's Avatar
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    Might be a kink in the fuel line from the previous replacement. That happened to mine...

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    Rice Hungry GottaHaveLS1's Avatar
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    Quote Originally Posted by 666ws6 View Post
    I'm no expert, but there is a lot online here so do a search. Assuming you checked your filter, you might be looking at dropping your tank to check the pump. I believe the regulator is in the tank. When do you see 25 psi, the entire time?

    I thought I needed a new pump awhile back, but turned out to be a problem with my MAF making me lean at WOT.
    if you read my post, you'll see that i already replaced my pump. I haven't seen my car in a month since i'm at school. all i know is that my dad brought it somewhere and we got a reading of 25 psi, i'll have to ask him the details.
    My tuner also suggested that it could be the MAF. I mentioned that in another thread here and people told me that the car would be at 50% power... which it isn't. Would driving the car with the MAF unplugged prove anything??
    Last edited by GottaHaveLS1; 09-25-2008 at 07:44 AM.

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    Rice Hungry GottaHaveLS1's Avatar
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    Quote Originally Posted by Goldcuffs View Post
    Unscrew the filter and check pressure there.Then you will know if it's something in the tank or up at the rail. If you suspect a vent solenoid (which I doubt it is) just unscrew the gas cap and see if you gain pressure. Does the car run? (It shouldn't on 25 psi)
    yes the car runs. it drives perfectly at low throttle. is there any kind of adapter to attach to the fuel filter line? i don't want to get gas everywhere and i couldn't find a tester kit that worked, so i'd have to take it somewhere again.

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    Rice Hungry GottaHaveLS1's Avatar
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    Quote Originally Posted by bills98ta View Post
    Might be a kink in the fuel line from the previous replacement. That happened to mine...
    I've thought of that... but i didn't see any problems anywhere. I've dropped the tank twice. A line got kinked once when i put the tank back in but i fixed it immediately.... unless it happened somewhere and i didn't notice.

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    Veteran 0rion's Avatar
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    if your fuel pressure was 25psi it wouldn't even start. Since you're not where you can look at the car or test things it's just a guess by everyone here what your issue is. I'd want to know what the pressure is at idle and under load. If the pressure is dropping to 25 under load I'd say it's probably related to your pump install. I think we've discussed this before about the tube that feeds your pump bucket being off or something along those lines.

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    Rice Hungry GottaHaveLS1's Avatar
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    Quote Originally Posted by 0rion View Post
    if your fuel pressure was 25psi it wouldn't even start. Since you're not where you can look at the car or test things it's just a guess by everyone here what your issue is. I'd want to know what the pressure is at idle and under load. If the pressure is dropping to 25 under load I'd say it's probably related to your pump install. I think we've discussed this before about the tube that feeds your pump bucket being off or something along those lines.
    my dad told me that the pressure was at 25psi when the guy revved it. I don't think it was while the car was being driven. So your saying there is a tube that brings gas into the pump assembly that could be kinked or something? looks like i'll have to drop the tank again....

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    Member Goldcuffs's Avatar
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    The first thing I would do is try a different gauge and test pressure your self. Like stated above if your pressure is 25psi, it shouldn't run. These engines are extremely sensitive to fuel pressure.

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