Author Topic: Homelite 2cycle string trimmer fuel line routing  (Read 2668 times)

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Offline Glanceblamm

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Homelite 2cycle string trimmer fuel line routing
« on: June 09, 2009, 01:55:02 AM »
I have an older Homelite string trimmer ST-145 that I did not run at all last Summer due to Illness. Needless to say, it wont start this year!...After confirming that it did have spark, I started with the exhaust side and that screen in the muffler was plugged. Still would not run due to hardened leaking fuel lines and a cracked primer bulb so I bought these parts.

I believe that the line off the primer bulb port on the carb is filtered and submerged but I do not know about the other line off the carb. My neighboor says that both lines are to be submerged in the tank as one supplys priming fuel to the carb while the other provides fuel to the carb for running the engine. I had looked at another make of a two cycle trimmer and found that the (non primer bulb line) just barely entered the tank so as to add positive pressure to the tank with the machine running? this makes sense to me.

I was wondering if any of you Homelite owners might take a peek inside the fuel tank to see if both lines are submerged or just one. These things seem to run well or very rough so your feed back is appreciated.
My existing lines were simply split & rotted of and laying inside the tank when I did the tear down.

Offline KeepTryin

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Re: Homelite 2cycle string trimmer fuel line routing
« Reply #1 on: July 21, 2009, 05:17:56 AM »
You may want to try the fuel lines both ways... I just went through some fun with my 15 year old McCullogh and it is running well now, but I learned that on mine, the primer is on the downstream or return side of the fuel circuit. In other words, the primer PULLS fuel through the carb. It then returns to the fuel tank with a shorter (but probably still submerged at times) line. The pickup line was much longer and had a filter on the end which probably helped it lay on the bottom of the tank. Of course mine isn't a Homelite but I thought I'd share this as it seemed counterintuitive to me. Guess I'm just used to old Ski-Doos that pulled the primer juice from the main fuel line and shot it into the spacer downstream of one carb...

Offline Glanceblamm

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Re: Homelite 2cycle string trimmer fuel line routing
« Reply #2 on: July 22, 2009, 10:27:58 AM »
Keeptryin, Those trimmings were getting tall and I had considered just purchasing some shot capsules for the .45 and doing a little snake hunting but the Wife (and the house siding) would not have taken this very well at all ;D

I moved quickly on the assembly and had the trimmer running within three days of making this post back in early June. I had pretty much taken your advice though and planned to try it both ways with the first being the long, or submerged line...makes it easier to shorten up the line that way if necessary but the machine ran like a Rolex wrist watch so this was one of the few times that I did not have to do a job twice!
Hardest part of this job is to get the new fuel line started into their respective holes on the fuel tank as the diameter is about the same and engineered this way because it is the only seal you get against leakage. A good tip is to whittle the line to a point to get it started in the hole then pressing while twisting will let you get it on in. Both lines were ran back out the fuel fill then squared off with a filter being installed on one and then the slack was pulled back through to the appropriate length.

Not much to that little carb. With the needle valves removed and the old primer bulb removed and discarded, I had four ports to use the common aerosol carb cleaner with the straw on and worked it back n forth several times.

This is an old machine as said already and I wondered about the cylinder compression but did not have a gauge to check it out. I know that the common 4 cycle lawn mower engine needs at least 65lbs of compression to even start but I cannot quote on the needs of a 2 cycle compression wise. I do know that it still has enough torque to turn the machine sideways resting loosely  in your hand and revving it up and still has enough power to tear up good sod if you let it.

The Wife was still a bit disgusted with me (till she heard that old trimmer run) for not  purchasing a new trimmer and I have to admit that a new 4 cycle model @ $159 was looking good. My parts cost me $11 though which saved quite a bit to spend on Powder n ball.

Offline KeepTryin

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Re: Homelite 2cycle string trimmer fuel line routing
« Reply #3 on: July 24, 2009, 03:58:02 AM »
...Yeah, getting the new fuel lines back through the tank wall! LOL! That was interesting for me too.

An old Chief Engineer I once worked for had a saying about "trying to push a wet noodle up a tiger's ....."

Glad your machine is working. I was on the verge of buying a cordless but perservered as well. Very satisfying to get something back in order like that, even if one has to answer questions about "why do you smell like gasoline?"