String trimmer leaks gas at fuel line to tank connection

Discussion in 'Mechanic and Repair' started by DeBrusher, Apr 26, 2014.

  1. DeBrusher

    DeBrusher LawnSite Member
    Messages: 12

    Hi all.

    I have an older string trimmer - Ryobi 780R. I have replaced all fuel lines on it. The return line is simply pushed inside the plastic gas tank through a hole on the bottom of the tank - a very iffy connection. When things get hot the gas begins to leak out of this connection - where the fuel line goes inside the tank.

    The fuel line I use is the yellow transparent line 3/16 OD x 3/32 ID.

    Any ideas on how I can fix this?

  2. herler

    herler LawnSite Fanatic
    Messages: 5,139

    I would find it hard to believe that it goes through without a grommet of some sort, here in this diagram Number 18 speaks of a fuel line assembly that looks to be just a bit more than a fuel line, whether it's worth spending the money is another story as I'm not 100% sure if it will fix this problem... Number 17 lists what appears to be a separate fuel line, I can't tell and I don't fool with Ryobi much, you may want to look at the diagram yourself and see if you can decide...
  3. JCLawn and more

    JCLawn and more LawnSite Fanatic
    from MI
    Messages: 5,281

    If it leaked when its hot out and the engine not running then I would bet your tank is over pressuring and your vent cap is not doing its job.
    Posted via Mobile Device
  4. herler

    herler LawnSite Fanatic
    Messages: 5,139

    I am curious as well, perhaps a length of fuel line 1/4" OD x 3/32" ID...
  5. DeBrusher

    DeBrusher LawnSite Member
    Messages: 12

    I think #18 is the intake line and #17 is the return line in the diagram. I have seen vids on YouTube describing the same setup as what I have - the return line is simply pushed into a hole in the tank.

    It seems that 1/4 x 3/32 line is not readily available. Maybe I can try 1/4 x 1/8 ? I have also thought about getting a nylon fitting and using it on the end of the line where it goes through the tank wall to get a tighter fit.

    Can you educate me on how the gas cap vent is supposed to operate? Does it let air in or lets the excess pressure out? What is the normal operating pressure inside the tank? Is it possible to clean the vent out in case some dirt is causing the problem? I do suspect my gas tank builds up too much pressure. The problem is worse when NOT running. It is also worse on sunny days.

  6. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,248

    Most 2/4 stroke tank vents, whether cap vents or a separate vent, are one way vents, permitting air to enter tank---to eliminate a vacuum occurring when fuel is used by the engine.
  7. tigerepairdotcom

    tigerepairdotcom LawnSite Senior Member
    Messages: 330

    I would find it hard to believe that it goes through without a grommet of some sort,

    You probably only work on high end/commericial 2 stoke stuff or otherwise. Most of the homeowners stuff is just wedged through plastic. I worked in a "shop down the street from the commercial power equipment repair shop." Poulan chainsaws, ryobi string trimmers, craftsman chainsaws which are now re branded poulan chansaws and a SLEW of other homeowners 2 stroke products are all just fuel line ran through the tank and sealed against the edges of the hole. .
  8. Patriot Services

    Patriot Services LawnSite Fanatic
    Messages: 14,261

    Yes they don't use grommets and its sucks. If it were me I would drill a hole and fit it with an Echo grommet and pipe combo. Not sure on exact size. Grommet and pipes are 15 bucks with filter.
    Posted via Mobile Device
  9. herler

    herler LawnSite Fanatic
    Messages: 5,139

    I don't think that would be a problem but another possibility might be 7/32" OD x 3/32" ID ?
    I really like that 7/32 OD, it would be a smaller increase than going to a 1/4" OD
    If it's available...

    Not sure if it helps but for 2-cycle fuel line I normally use a Tygon PVC tubing, which might be hard to find by the foot...
    Home Depot does sell some pvc tubing in 10 foot sections in their plumbing department, whether they have the right size is another story.
    Last edited: Apr 28, 2014
  10. herler

    herler LawnSite Fanatic
    Messages: 5,139

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