Leaking fuel injectors?

Discussion in '2005+ Mustang GT 4.6L Tech' started by rdsx18, Apr 19, 2021.

  1. rdsx18

    rdsx18 forum member

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    Been a while since I posted here, but I'm having some issues with starts lately. I've got a 2005 GT with a magna charger and comp cams. Cold starts were very rough for a few seconds, I'd crank it, AFR would peg rich, then the car would stumble and I'd have to stay in the throttle to keep it going. I checked the plugs and had a few bad ones so I swapped those and it helped somewhat, but it still starts rough.

    What I'm thinking might be happening is am injector or 2 are leaking down and causing the rough starts, since it really only happens after the car has sat 4-10 hours. If it sits fully overnight, it's perfectly fine. I checked my fuel pressure at the rail and it drops 5 psi over 5 or so minutes, another 5 over a few hours, then maybe 20 overnight. Other things to note, after checking the fuel pressure, it started real rough with white fuel smelling smoke. I changed the oil, it doesn't smell like fuel and was a normal color. Other than this issue, the car runs perfect, anyone have any ideas? Just looking for some input or other things I could try before dropping 500 on new injectors.

    Thanks!!

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  2. jdlatil

    jdlatil Twin Srew Driver

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    Are you return style fuel system?
     
  3. rdsx18

    rdsx18 forum member

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    Factory system with a BAP, so returnless I believe. I realize it will bleed pressure somewhat anyways, just not sure how much is normal.

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  4. jdlatil

    jdlatil Twin Srew Driver

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    I would run a couple of tanks of gas with fuel injector cleaner though car.

    when you shut car off each time make sure you let it settle down to an idle before turn key off. Keeps any extra fuel from building up. Also check you air filter.
     
  5. Juice

    Juice forum member

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    Probably not leaking injectors, but the easiest way to tell is remove the fuel pump relay when you shut off the car. Then let it sit. It should NOT attempt to even sputter if the injectors are NOT leaking. You could also monitor the fuel trims, leaky injectors should throw adaptives well into the nevgative.

    I would be more inclined to think the tune is a bit on the rich side.

    From personal experience, when I had a leaking injector it actually filled the cylinder with gasoline.
     
  6. rdsx18

    rdsx18 forum member

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    I had been running a can of seafoam through it every tank and it improved slightly, but not completely. I just bought a half dozen more so I'll be running it every tank for a bit.

    I always let it idle for a bit then shut off, air filter is fresh too.

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  7. rdsx18

    rdsx18 forum member

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    Thanks for the insight, I'll have to try that. I considered the tune, but the tuner is very reputable and I did actually have him tweak it. I also don't get why it's only rough for a few seconds after startup, it's not like it warms up any during that time.

    For what it's worth, the tuners best suggestion was to add catch cans, I did and I hardly collect any oil in them, maybe a teaspoon per oil change, and my intake is always clean, never oil residue at all.

    Edit: I was just thinking, would there be a downside to unplugging all the injectors then trying to turn it over? Or does the fuel pump relay cut power to the injectors as well?

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    Last edited: Apr 21, 2021
  8. Juice

    Juice forum member

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    I tune my own. I had the "too rich" issue, just not as bad. It was mostly the cloud of blue smoke on startup. With the only mod a "tune required" CAI. And completely stock engine/tune/exhaust. No large injectors, or blower. (yet lol) Issue completely disappeared after I installed a stock airbox with stock maf in the tune.

    And unplugging all injectors is a much better test. I completely forgot pulling the relay for the fuel pump will not work. Pulling the fuse that fees the injectors is what my brain was thinking, and I typed "fuel pump relay". DOH
     
    Last edited: Apr 21, 2021
  9. rdsx18

    rdsx18 forum member

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    Lol no problem! Over the next few days I'll prime the system then disconnect the injectors and try to turn it over and see what happens!

    I'm getting a puff of white smoke on startup, I was nervous it was a coolant leak at first but the oil is clean, so hopefully I'm ok there.


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  10. Juice

    Juice forum member

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    Coolant/headgasket issues leave clouds of white smoke when engine warms up. I would not be concerned.
     
  11. rdsx18

    rdsx18 forum member

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    Just wanted to give a quick update here, haven't checked the injectors but I have been running Berrymans every tank and it is way better, only 1 start in the last few weeks where it stumbled.

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