96 V6 3.8 Fuel pressure problems

Discussion in 'SN95 V6 Mustang Tech' started by BrandonM, Mar 19, 2011.


  1. BrandonM

    BrandonM New Member

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    The problem started while driving on the highway at 55mph, it just died as if it ran out of gas. I had just filled the tank. Replaced fuel filter and it ran good for a week and same problem started where it would start and stall out. Could not drive at all. Just replaced the fuel pump and now it starts and runs at idle only. Fuel pressure test shows 22psi at idle, as soon as gas peddle is pushed and car revs up pressure drops to zero and car stalls. Any trouble shooting suggestions would be greatly appreciated
     
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  2. BrandonM

    BrandonM New Member

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    how did the zip it icon get in my post, must be a mistake, sorry
     
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  3. Gearbanger 101

    Gearbanger 101 Straight Outta Locash Super Mod

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    Fuel presure regulator perhaps? Shouldn't it be about 40psi at idle?
     
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  4. MustangLX-5.0

    MustangLX-5.0 Founding Member

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    Idle fuel pressure should be around 38 - 40 PSI. Your pressure is way too low. First, I'd take a look at that pressure regulator, it could be stuck or clogged. There also may be some contaminants in your gas. That's just a thought tho. Do you have a Check Engine light on?
     
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  5. BrandonM

    BrandonM New Member

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    Thank for the replies. Will check the fuel pressure regulator next.
     
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  6. BrandonM

    BrandonM New Member

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    Just changed fuel pressure regulator, the old one was bad. Still only getting 22psi at idle and when rev up psi drops to zero, let up on gas peddle before stalling out the pressure returns to 22psi. Can not find any gas leaks. Any suggestions. Frustrated and confussed.
     
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  7. BrandonM

    BrandonM New Member

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    how would i check to see if one of the fuel injector o rings is leaking? is there a way to check to see what cylinder it may be?
     
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  8. BrandonM

    BrandonM New Member

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    Still having low fuel pressure. Cleaned MAF sensor and checked fuel injectors. The next step is checking the wiring to the inertia switch, etc. Found an awesome post regarding the wiring in the 5.0 forum. This may be the problem. Prior owner bypassed the inertia switch altogether and just connected wires together with elctrical tape.

    Pressure is at 24 at idle and drops to zero when you hit the gas. If we remove return fuel line at the rail and plug it so no fuel can return to fuel tank, pressure remains at 22 psi, shouldn't pressure go way up when you do this? Any other suggestions??? :shrug:

    Replaced fuel pump, fuel filter, new battery, new fuel regulator,MAF checked and cleaned.
     
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  9. Gearbanger 101

    Gearbanger 101 Straight Outta Locash Super Mod

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    No chance you've got a kinked or obstructed fuel feed line?
     
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  10. 1987LXragtop

    1987LXragtop Member

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    That happened to me on my 5.0. turned out that the line that connected the fuel pump to the upper part of the outlet from the tank had failed.
     
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  11. BrandonM

    BrandonM New Member

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    1987LXRagtop, that is exactly what the problem was. Changed the line and is running well. We are now doing some body work and going to get it painted. Had some ugly bright yellow flames on hood and front cornor panels. Thanks to all for troubleshooting suggestions.
     
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