95 Cobra Fuel Issue

Discussion in '94-95 5.0 - Specific' started by 1Fine99, Feb 17, 2016.

  1. 1Fine99

    1Fine99 New Member

    Messages:
    44
    Likes Received:
    0
    Joined:
    Sep 15, 2014
    Lately (and somewhat intermittently) my 95 will have a hard time starting. The engine will crank and not start but if I turn the key off and then try to start it again right away it will fire up immediately. Car seems to run totally fine once it's started.

    Yesterday I hooked up my fuel pressure gauge and with the key on and engine off the gauge was not showing any pressure. With the engine running I was seeing 30-31 psi. With the vacuum line removed from the fuel pressure regulator I was seeing closer to 40 psi (also no signs of fuel leaking from FPR). When I shut the engine off the pressure would drop back down to 0 immediately.

    I'm curious if anyone has had a similar issue and what the cause was. From doing some research it sounds like it may be the check valve in the fuel pump? Is there anything else that could cause symptoms like this? Leaky injector?

    For what it's worth, the car has a new Motorcraft fuel filter, plugs, plug wires, cap, and rotor.
     
  2. CC'S95GT

    CC'S95GT Legend

    Messages:
    10,738
    Likes Received:
    172
    Joined:
    Apr 19, 2008
    Location:
    Hampton ,Ga.
    I don't think it a problem with the pump but with the FPR instead.
     
  3. 1Fine99

    1Fine99 New Member

    Messages:
    44
    Likes Received:
    0
    Joined:
    Sep 15, 2014
    Thanks for replying. Do you think the diaphragm inside is bad? I haven't seen any fuel leaking from it when I've had the vac line off and my fuel pressure goes up when I pull the vac line off. That means the diaphragm is working right?
     
  4. Addermk2

    Addermk2 Well-Known Member

    Messages:
    2,505
    Likes Received:
    32
    Joined:
    Mar 7, 2006
    this will not be an FPR issue. that much is apparent due to the fact that its doing exactly what its supposed to. You have 40psi running w/o vac ref, and low 30s with vac ref.

    Your problem is going to be the small S hose inside the tank. It has likely failed, and you are losing pressure inside the tank. Its basically a fuel leak, but still inside the tank.

    Drop the tank and pull the sending unit out. replace the S hose, and im 98% sure your issue will go away.
     
  5. rz5.0

    rz5.0 Legend

    Messages:
    5,853
    Likes Received:
    130
    Joined:
    Mar 26, 2010
    Location:
    Great state of TEXAS
    /\ /\ what he said more than likely. Or the check valve on the pump.. Your fuel is draining back to the tank.. When the fpr goes bad it leaks gas from the vac plug and you get a weird idle and rich condition..

    Sent from my LGLS991 using Tapatalk
     
  6. evilcw311

    evilcw311 Most Evil Mod! Staff Member Staff

    Messages:
    7,181
    Likes Received:
    1,800
    Joined:
    May 9, 2010
    Location:
    Louisville, KY
    Didnt someone else have this same issue recently?!?

    Adder has it right. Drop the tank and the problem should be obvious. If your planning any other mods soon it might be time to upgrade your pump while your at it.


    This message courtesy of crapatalk!
     
  7. Mustanger

    Mustanger Well-Known Member

    Messages:
    2,310
    Likes Received:
    115
    Joined:
    Dec 3, 2006
    Location:
    Southern Oregon
    So Glad you are here Adder !! Thanks for your advice it really helps us.....And all you other members with good advice I & many others rely on you a lot.
     
  8. 1Fine99

    1Fine99 New Member

    Messages:
    44
    Likes Received:
    0
    Joined:
    Sep 15, 2014
    Thanks for the info, I appreciate it. I decided to just order a new fuel pump. Do you know why the hoses usually fail? Just deterioration due to age? I guess I'll find out once I get the old pump assembly out.
     
  9. Addermk2

    Addermk2 Well-Known Member

    Messages:
    2,505
    Likes Received:
    32
    Joined:
    Mar 7, 2006
    Most fuel now a days is an ethanol blend.

    The S-hose that came with the car from the factory is probably an SAE J30R9 or below. Which means it's submersible, yet still not compatible with ethanol.

    For any kind of ethanol blend (even E10) you need SAE J30R10.
     
  10. 96blak54

    96blak54 Legend

    Messages:
    7,471
    Likes Received:
    781
    Joined:
    Feb 21, 2011
    Location:
    Ky
    I have to admit adder is a 94-95 sn95 dictionary. Good that so much wealth of info offered kindly!
     
  11. 1Fine99

    1Fine99 New Member

    Messages:
    44
    Likes Received:
    0
    Joined:
    Sep 15, 2014
    I dropped the tank today and pulled out the sending unit. The S hose appears fine. There are no visible cracks or holes in it. The only thing I noticed is the little orange rubber cap has a tear in it...but I'm assuming it's supposed to be like that since it's on the return line?

    [​IMG]
     
  12. Addermk2

    Addermk2 Well-Known Member

    Messages:
    2,505
    Likes Received:
    32
    Joined:
    Mar 7, 2006
    Might as well put a pump kit in.
     
  13. 1Fine99

    1Fine99 New Member

    Messages:
    44
    Likes Received:
    0
    Joined:
    Sep 15, 2014
    That's the plan since I already have it. Do you know what the purpose of the orange rubber cap on the return line is?
     
  14. 1Fine99

    1Fine99 New Member

    Messages:
    44
    Likes Received:
    0
    Joined:
    Sep 15, 2014
    Got the new fuel pump installed today. Haven't driven the car yet but it is now holding fuel pressure after I prime the pump so it appears as if the new pump solved the issue. :thumbsup: