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Thread: Leaking fuel injectors after ultrasonic cleaning

  1. #1
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    Leaking fuel injectors after ultrasonic cleaning

    G'day brains trust. This question, like other questions lately, regards my 2008 Jaguar XF that has the 4.2 litre supercharged V8 engine shared with the Range Rover of the same era.
    I recently did some major work on the car, it had a blown coolant hose that necessitated removal of the supercharger to access and, unlike the Range Rover, the blower can only be removed by taking the engine out of the car. Whilst the blower was off, as well as servicing the blower itself (new snout bearings and coupler) and replacing all coolant hoses (there are about a thousand of those) I decided to take the intercoolers off and give them a good clean out, as well as getting the injectors cleaned. The car was running great but with 160,000km on the clock it seemed worthwhile, as the injectors are only accessible with the intercoolers off and the intercoolers are only accessible with the blower off and the blower can only be removed with the engine out.....!!
    Well I am now in the incredibly frustrating position of having a starting problem that is almost certainly being caused by leaking injectors. A little research suggests that this is a known side effect of cleaning the injectors; tiny deposits find their way further downstream and prevent the injector from fully closing. If I had known this I would have left well enough alone, but I did not. An 'unknown unknown'.

    I have done a fuel pressure test and there is definitely a pressure drop through the injectors with the engine off; from 55psi running pressure down to 40psi in 3 minutes, 35psi in 5 minutes and down to about 10psi after being left for a couple of hours. Holds 47.5psi after 3 minutes and then an almost imperceptible rate of pressure drop when the line to the fuel rail is clamped off. No external leaks, so it can only be going through the injectors.

    I'm now looking at the likelihood of repeating the whole job to replace the injectors that were previously working fine. About 2 days work to remove and reinstall the engine but additional costs of renewing supercharger & intercooler gaskets and regassing the a/c.

    My question then is, does anyone know of a way to solve this problem without removing the injectors from the vehicle or, if not, a way to solve this problem without replacing the injectors?

  2. #2
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    Where is the regulator for the rail pressure?
    Are you checking individual leak down or the rail?

  3. #3
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    Quote Originally Posted by Tombie View Post
    Where is the regulator for the rail pressure?
    Are you checking individual leak down or the rail?
    There isn't a regulator in the sense of a return-to-tank type system, there's an electronic pressure sensor on the rail and the in-tank pump is ECU controlled with a fancy 2-way valve arrangement, it supplies the pressure from the tank. No schraeder valve on the rail either. The entire fuel rail and injectors are cunningly concealed under the supercharger and intercoolers. To measure the pressure, I teed into the feed line at the filter which is behind the left-front inner guard. I can't see any way to test injectors individually without stripping everything down. Pulling spark plugs after a start is the only way I can think of to see which injector/s are likely culprit.

  4. #4
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    Perhaps if you made the engine do some hard work (burn a lot of fuel) it might flush the injectors, or even just a decent run of a few thousand kms.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
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  5. #5
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    ok so...

    drain the oil.

    remove the spark plugs and us a venturi style vacuum unit dumping into a pool of water and non sudsing degreaser (60l drum half full) hook up onto the spark plugs,

    put a hot mix of a fuel system decoking agent into the tank and manually run the pump, power up each injector using a flasher can driving a relay and a suitable light to get a 3-5 click/sec ratio as you vac the cylinder via the plug hole.

    run each injector for about a minute then redo your pressure test.

    with such a low pressure drop rate it may well be an injector oring seal.
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    Tdi autoManual d1 (gave it to the Mupion)
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  6. #6
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    Quote Originally Posted by Blknight.aus View Post
    ok so...

    drain the oil.

    remove the spark plugs and us a venturi style vacuum unit dumping into a pool of water and non sudsing degreaser (60l drum half full) hook up onto the spark plugs,

    put a hot mix of a fuel system decoking agent into the tank and manually run the pump, power up each injector using a flasher can driving a relay and a suitable light to get a 3-5 click/sec ratio as you vac the cylinder via the plug hole.

    run each injector for about a minute then redo your pressure test.

    with such a low pressure drop rate it may well be an injector oring seal.
    That's an interesting idea. I would be disinclined to put anything other than fuel in the tank though, the in-tank fuel system components are complex and expensive- I considered running a higher-than-spec mix of injector cleaner (by putting a couple of bottles in a near-empty tank) but when I read the manual regarding the pump and other gadgetry in the tank I decided against it. I could tap into the line at the filter and run something just through the rail and injectors though. Good idea to pull the spark plugs and evacuate from there.
    I think though that the spray nozzle at the injector tip is a smaller orifice than the open / close mechanism; these injectors have seven holes at the business end. I'll look into that a little further.

    I'm confident there are no leaks at the O-rings; no petrol smell, nothing seen with the inspection camera.

    I have been giving it some full-power runs to maximise the fuel flow in the hope that it will self-flush. Trouble of course is that I run out of room pretty quick and doing full-throttle bursts sees the speed limit exceeded in about 5 seconds.

  7. #7
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    Sounds like a road trip for the long weekend. Recommended dose of injector cleaner in several tanks of fuel, add some music of choice, nice scenic route, pub lunches, a clean fuel system when you get home.
    Great way to spend a weekend
    Just don’t go near Brisbane!
    Phil B

    Custodian of:
    1974 S3 swb wagon (sold)
    1978 S3 swb canvas
    48 749 '88 4x4 Perentie
    1985 County with 4BD1T

  8. #8
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    Quote Originally Posted by POD View Post
    That's an interesting idea. I would be disinclined to put anything other than fuel in the tank though, the in-tank fuel system components are complex and expensive- I considered running a higher-than-spec mix of injector cleaner (by putting a couple of bottles in a near-empty tank) but when I read the manual regarding the pump and other gadgetry in the tank I decided against it. I could tap into the line at the filter and run something just through the rail and injectors though. Good idea to pull the spark plugs and evacuate from there.
    I think though that the spray nozzle at the injector tip is a smaller orifice than the open / close mechanism; these injectors have seven holes at the business end. I'll look into that a little further.

    I'm confident there are no leaks at the O-rings; no petrol smell, nothing seen with the inspection camera.

    I have been giving it some full-power runs to maximise the fuel flow in the hope that it will self-flush. Trouble of course is that I run out of room pretty quick and doing full-throttle bursts sees the speed limit exceeded in about 5 seconds.


    drop the line from the rail, plumb on any efi 60psi pump and run the hot mix out of a jerry can.

    if you're going to do this drop the oil first, once you're done flushing the injectors vac the sump for a few minutes then refill, throw a teaspoon or so of oil down the plug hole before you fill the oil, crank on the starter with the plugs out until the oil light goes out to make sure your bores are lubed then plugs in leads on and crank it.


    dont forget that for your full power runs you can drag the brakes to load it right up and lift the engine temps.
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    Tdi autoManual d1 (gave it to the Mupion)
    Archaeoptersix 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

  9. #9
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    Quote Originally Posted by Phil B View Post
    Sounds like a road trip for the long weekend. Recommended dose of injector cleaner in several tanks of fuel, add some music of choice, nice scenic route, pub lunches, a clean fuel system when you get home.
    Great way to spend a weekend
    Just don’t go near Brisbane!
    Hah that sounds like a great idea Phil and certainly worth a try. Unfortunately the Easter weekend is all work for me, including a Saturday night shift of 15 hours instead of 14 thanks to the end of daylight saving. It's still an enormously enjoyable car for a road trip- once it's started! The Licola road mid-week is a pretty pleasant place to burn some 98-octane....

  10. #10
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    Great idea.
    It’s there to be enjoyed!
    I too won’t be going anywhere this Easter, so don’t feel alone!
    Phil B

    Custodian of:
    1974 S3 swb wagon (sold)
    1978 S3 swb canvas
    48 749 '88 4x4 Perentie
    1985 County with 4BD1T

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