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Fuel presure dropping after shut down.

This is a discussion on Fuel presure dropping after shut down. within the External Engine forums, part of the LSx Technical Help Section category; I know this is a LS1 sight but like other guys I have more than one ride to keep up.My ...

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    Fuel presure dropping after shut down.

    I know this is a LS1 sight but like other guys I have more than one ride to keep up.My wife have a 2003 ford sport trac with the 4.0 engine that is giving me problems, I hope some of you can help me get it fixed, I can smell gas coming from the truck I have checked for fuel leaks top and under truck nothing,I ran a fuel pressure test and it showed 64 which I was told was good but the minute you shut off the truck the pressure drops fast to 0, could it be injectors leaking , and if so would I smell gas like I do if they were doing so at the tip and not outside where I could see it.need help this is my wife's work truck and she
    is in it 5hrs a day need to solve this as soon as I can.the truck have 161,000 miles on it.

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    Fuel presure dropping after shut down.

    if the truck a fuel pressure regulator on the return line at fuel rails pull the vacuum line and see if gas runs out . the diaphragm goes bad and leaks through the vac port . that is if it has that style of injection with a return. to tank .

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    is the truck running ok? Have you tried turning the key on/engine off and checking pressure that way? Is smelling gas the only symptoms you have I guess is my main question or is the truck running badly? Any codes? If it's just fuel odor I would check evap lines/canister too and make sure none are leaking although you technically should have a code if those are leaking. How strong of an odor are we talking?
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    I'm on here looking up the same issue on my 2002 ws6. The fuel pump has a check valve built in, if that fails, you'll lose pressure as soon as you shut down, and have harder start as it needs to prime the lines every start.

    I'm looking for info on adding a secondary, in-line check valve to help out rather than pulling the fuel pump itself...

    --alex

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    you're thinking the fuel pressure regulator I think.....it's part of the module. Someone on here did have a part number for it at one time but I forget who it was....I think it was pajeff.

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    The regulators for the LS1's were tough to come by, but I did track them down. I will check to see if I can find the thread.

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    Quote Originally Posted by 0rion View Post
    is the truck running ok? Have you tried turning the key on/engine off and checking pressure that way? Is smelling gas the only symptoms you have I guess is my main question or is the truck running badly? Any codes? If it's just fuel odor I would check evap lines/canister too and make sure none are leaking although you technically should have a code if those are leaking. How strong of an odor are we talking?
    The smell is pretty strong I have checked for leaks I have no codes and the truck seems to run ok but I feel it has run better, the smell seems to be strongest when the weather is hot. The smell seems to be coming from under the truck close to the gas tank but I can't find any leaks, I will be getting back under it and check all the hoses on the tank.I have put new plugs and wires on it but I my need to go on and put on a new coil.I will report back and let you guys know what I find Thanks.

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    I have found the source of my problem, I have a line on top of the tank that is spraying gas from the connection to the fuel pump,there is two lines on top of the pump I hope one of them
    is
    a return line , I hope to lower the tank and try to fix the leaking line, I have never removed the fuel lines on a ford so I hope someone on here can give some pointers.I have watched it done on line but there is nothing like doing it your self.My wife have one day off work so the pressure is on me to get it done tomorrow,wish me luck.remember it's a 2003 ford sport trac not my 99 TA.
    Last edited by Street Fighter; 08-24-2015 at 09:10 PM.

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    Fuel presure dropping after shut down.

    There are plastic clips that hold the lines to the pump assembly. its possible one is cracked or broken.

    Did you do the trap door? You should be able to disconnect without dropping the tank.
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    Quote Originally Posted by SMWS6TA View Post
    There are plastic clips that hold the lines to the pump assembly. its possible one is cracked or broken.

    Did you do the trap door? You should be able to disconnect without dropping the tank.
    I don't know about the trap door saver , can you show picture or explain it to me. I did do one on a jimmy I had but never a ford.remember there is gas on top of the tank from the leak.any cutting could end bad .

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    Fuel presure dropping after shut down.

    just put a new fuel pump in it and be done.

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    Fuel presure dropping after shut down.

    ws6- I have a 4th gen trans am and the trap door location is obvious once you've located the mark. pull up the carpet and there will be lines that like an factory crease. look for the half line and its right above it cut about like a 12" by 10" square with a rotary tool after you get under your car and loosen the strap bolts that holds your tank. do not have to drop the tank, just need enough space for the cutting wheel so you dont cut into your tank.

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    Quote Originally Posted by Ls2 bird View Post
    just put a new fuel pump in it and be done.
    He said it was bad lines. Why would you replace a good pump? A fuel pump doesn't come with fuel lines.
    It's on jackstands.

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    I second that ,why would I buy a new fuel pump and still have the same problem which is a leak at the conection on the line.

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    Quote Originally Posted by Street Fighter View Post
    I have found the source of my problem, I have a line on top of the tank that is spraying gas from the connection to the fuel pump,there is two lines on top of the pump I hope one of them
    is
    a return line , I hope to lower the tank and try to fix the leaking line, I have never removed the fuel lines on a ford so I hope someone on here can give some pointers.I have watched it done on line but there is nothing like doing it your self.My wife have one day off work so the pressure is on me to get it done tomorrow,wish me luck.remember it's a 2003 ford sport trac not my 99 TA.
    another piece of the post that was missed.......


    I've never done fuel lines on one of those but how hard can it be right? Getting to it will be the biggest bitch. Wonder if it's like any other pick up truck and easier to just pull the bed off than to drop the tank. I've had the bed off of a ford ranger and it's literally 6 bolts and a couple electrical connections to the tail lights ( 2 of the bolts were a different length so pay attention to the bolts). Easier with 2 people but me and a buddy had his bed off to replace a broken leaf spring in about 15 minutes. The sport track has a plastic kick panel that runs the bottom of the the bed rails but if you can get to everything you may be better off just pulling the bed off.

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    Quote Originally Posted by 0rion View Post
    another piece of the post that was missed.......


    I've never done fuel lines on one of those but how hard can it be right? Getting to it will be the biggest bitch. Wonder if it's like any other pick up truck and easier to just pull the bed off than to drop the tank. I've had the bed off of a ford ranger and it's literally 6 bolts and a couple electrical connections to the tail lights ( 2 of the bolts were a different length so pay attention to the bolts). Easier with 2 people but me and a buddy had his bed off to replace a broken leaf spring in about 15 minutes. The sport track has a plastic kick panel that runs the bottom of the the bed rails but if you can get to everything you may be better off just pulling the bed off.
    I thought about that but even with the bed off you still can't get to the fuel line because ford had a great ideal to run a support bracket over the pump. plus the pump is located about 18" under the cab.

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    I Am not sure about the 2003 ford sport trac, but my 2001 Chevy Silverado 1500 fuel tank was pretty easy to drop. Just 2 bolts hold the tank to the frame, and the few bolts holding the fuel filler neck to the truck also. I used a few 2x4's and a hydraulic jack to lower it down just enough to get to the top of the tank. Obviously the less fuel in the tank, the better off you are, but I don't think it will be to bad to do. Good luck.
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    Sorry OP, I was thinking this was a F-body when referring to the trap door. I had posted my msg from my phone and didn't see it wasn't.

    But the plastic clips I was referring to is still valid. Here is what I was referring too.

    Last edited by SMWS6TA; 08-25-2015 at 07:35 AM.

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    Thanks to all that gave me advice on this issue, I got her done.I ended up replacing the pump, one of the nipples on the pump was cracked and was spraying the fuel under the cab, I feel a lot better knowing my wife is safe driving the truck .once again thanks.

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