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Thread: air leaks, fuel leaks, return system...questions

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    Default air leaks, fuel leaks, return system...questions


    Few questions:

    1. Can a small leak in the fuel return lines system (or injector line to injector) cause a stumble/miss at low rpm (1k-1.5k)? talking about a leak that is small enough not to be seen, but I assume is there.

    2. Is it beneficial to use teflon tape so something of the sort to seal the injector line to the injector (small amount). Especially if the threads on the injector or injector line fitting are semi-buggered up?

    3. I know a lot of people have problems with the return line o rings shrinking (or not sealing well) and causing air intrusion/leaks in the return system. Do you think a fuel additive like Power Service (grey bottle or white bottle), or Howes would help to keep not only the fuel system lubricated but also keeps the rings from shrinking?

    4. Is there any fuel additive that could be run that would slightly swell the o-rings to cause them to seal better?

    5. Would there be any benefit to using worm-gear style clamps on the return line setup instead of the regular red spring style clamps? I know that you would have to take care not to crank on them extremely hard so that they wouldn't cut into the hose, but it seems like you can be better assured that the clamp is tight with these (I hate spring style clamps... don't know why).

    6. What type of clear hose are you guys using to check for air intrusion in your system. I know that most run it from the filter head to the 1st return line, but are you using some form of clear fuel line or chemical resistant line? If so, where are you getting it? It would seem to me that regular clear tubing would be eaten up by diesel fuel fairly quickly.

    Some of these questions apply to my truck, and some are just for my personal information. Any informative responses are appreciated!
    Last edited by coletrain777; 01-06-2011 at 12:32 PM.

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    Full Access Member joe f350's Avatar
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    get a return line kit do them all at once cause once u disturb one the others will start to leak it is easyer to do all the injectors at wonce

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    Using the Force! Agnem's Avatar
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    1 - Once an engine is running, any leaks in the return line system will not effect run quality. Only during shutdown is a return line leak an issue.

    2 - You cannot use any sealant. Replace anything that is munged up.

    3 - A new return line kit is your solution. A properly installed kit should last for years and years.

    4 - swelling = softness. Not good.

    5 - I've seen it done, but honestly I don't think there is any benefit. See #3.

    6 - run of the mill clear vinyl tubing will work for a short time. Don't leave it in place for weeks on end.


    Quote Originally Posted by coletrain777 View Post
    Few questions:

    1. Can a small leak in the fuel return lines system (or injector line to injector) cause a stumble/miss at low rpm (1k-1.5k)? talking about a leak that is small enough not to be seen, but I assume is there.

    2. Is it beneficial to use teflon tape so something of the sort to seal the injector line to the injector (small amount). Especially if the threads on the injector or injector line fitting are semi-buggered up?

    3. I know a lot of people have problems with the return line o rings shrinking (or not sealing well) and causing air intrusion/leaks in the return system. Do you think a fuel additive like Power Service (grey bottle or white bottle), or Howes would help to keep not only the fuel system lubricated but also keeps the rings from shrinking?

    4. Is there any fuel additive that could be run that would slightly swell the o-rings to cause them to seal better?

    5. Would there be any benefit to using worm-gear style clamps on the return line setup instead of the regular red spring style clamps? I know that you would have to take care not to crank on them extremely hard so that they wouldn't cut into the hose, but it seems like you can be better assured that the clamp is tight with these (I hate spring style clamps... don't know why).

    6. What type of clear hose are you guys using to check for air intrusion in your system. I know that most run it from the filter head to the 1st return line, but are you using some form of clear fuel line or chemical resistant line? If so, where are you getting it? It would seem to me that regular clear tubing would be eaten up by diesel fuel fairly quickly.

    Some of these questions apply to my truck, and some are just for my personal information. Any informative responses are appreciated!
    Owner, Conestoga Diesel Injection Our family - The Moose Truck - 1983 F-250HD, The Lady Moose - 1993 F-350 CC dually, The Moosestang - 1987 Bronco (1994 7.3L IDI), The Night Moose - 1995 F-150 (1984 6.9L IDI), The Iron Moose - 1986 F-250 EC, The Moose Wagon - 2002 Excursion, The Moose GT - 2008 Mustang GT 4.6L, The Moose Lodge - 1994 Wilderness 195R Serving the IDI community since 1997! Visit http://MoosePump.com or https://www.facebook.com/ConestogaDiesel

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    So what about a tiny amount of seepage between an injector line and the injector (at the fitting), would this effect run quality? The leak is very insignificant, I can just notice a minor amount of fuel around the fitting after driving for a while. The problem is that the injector line fitting is tight on the injector (no more tightening to be done). How would I fix this???

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    Return line kit is new, just wondering about the setup.

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    IDI Probbie FordCoalRoller's Avatar
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    I replaced the return line kit on mine because i was having a starting problem and they were leaking. They are not leaking now but still have the issue it looks like the injection pump itself is leaking around the advance mechanism. I only have a problem with studdering in that rpm range when i let my fuel and close it E and the fuel is sloshing around.
    1992 Ford F-250 Extended Cab, 7.3L IDI (turn 1.5 flats), 5-Speed 2WD

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    I wouldn't advise any sealant on the high pressure lines.If it won't seal check to see if the injector is bunged up or the flared fitting in the line.If it's the line replace it-if its the injector replace that. Or replace them both.

    One thing have always done is make sure the return lines between the injectors dont have a curve in them caused by being a little over length if I have to have a curve I make a loop to take pressure off the t fitting & O-ring.In my opinion it makes a safer seal that will last. The spring clips are fine I don't think I have evr seen a leak in a decent set of lines & good T fittings.
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    Diesel junky BigRigTech's Avatar
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    The clear the vinyl line is tough, mine has been on there for almost a year - just the same as it was when I put it on.
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