Gas tank pressure problem on Maruyama hedge trimmer

Dawson

LawnSite Bronze Member
Location
Valrico, FL
I have some fairly new older model Maruyama hedge trimmers (model HT2320DL-R).

I mount them in my trailer blades down so the engine is vertical.

The problem I'm having is when they are in the sun for a while on the trailer the gas tank builds up pressure and forces gas out through the little pressure relief valve. The tank cap on these has no valve in it either.

I'm assuming this is happening because of how I store them, vertically, rather than laying down horizontally, so that the tube that the pressure valve is attached to is submerged in gas rather than air?

I'm looking for ideas to resolve this problem? Other than changing the way I store them that is:confused:
 

jkilov

LawnSite Bronze Member
Location
MS
Good equipment usually has a "duckbill" type one-way valve held near the intake. It's a rubber part encased in a plastic housing and can become brittle as time goes on. It normally holds both gasoline and fumes from escaping when under pressure, but allows air to enter when facing vacuum.

Replace this part and you shouldn't have any more problems.
 

tigerepairdotcom

LawnSite Senior Member
Location
duluth, ga
OP
D

Dawson

LawnSite Bronze Member
Location
Valrico, FL
They were doing this when brand new and I've replaced the duckbill valve already, I just don't know why this one piece of equipment is building up that much pressure in the tank that it forces gas out through the duckbill when none of my other 2 stroke equipment does.

Tell me if this makes sense?.... the way I store them puts fuel over the opening of that vent tube inside the top of the tank where if the tool is stored horizontally (the position it is normally run in) it would only let fumes escape if that much pressure builds since the fuel would not be covering the vent tube opening?

So If I want to continue storing them the way I do I would need to put a second vent tube at the high point on the tank when it is vertical? so when pressure builds to the point it forces the duckbill to to open the wrong way the gas fumes can escape rather than the gas itself?

Just trying to understand why it's happening so I can come up with a solution.
 
OP
D

Dawson

LawnSite Bronze Member
Location
Valrico, FL
You could put something over them to give them shade. It is August in FL.


lol, yeah but it does it even in the shade, it's August in FL;)


I just finished modifying it so hopefully what I did will solve the problem for the most part.

I pulled out the flexible vent tube that ended just inside the gas tank and replaced it with a piece of stiff tube that will stand up on it's on. I ran the new piece of tube (with a couple of small V's cut in the end) all the way to what is the top of the tank when they are stored vertically so that unless the tank is completely full the end of the tube is up in the air space.
It may still lose a little fuel from what splashes into the tube but hopefully I won't lose a whole tank full of gas anymore. Hopefully doing this won't cause any issues while in use either, I don't think it will as long as the clunk doesn't get hung up on the vent tube.

Thanks for the help in understanding what's going on with it.
 

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