Homelite trimmer F2020

Your missing the last digit of the model number.

UT-20788 and UT-20789 uses the UP00608 carburetor which is a ZAMA C1U-H39.

First make sure the on/off has tried in both directions. Even here in the shop I sometimes forget to set those switches that don't have the momentary off postion.

Then if still doesn't start then I would treat it as if run at sometime and go thru the basic troubleshooting of a won't start engine.

• Check for spark. No equals ignition problems.

• If you have spark then
• Try putting a little fuel mix in the cylinder via the spark plug hole to see it will try to start. if tries to start then carburetion problems. Yes even with an used carburetor.
• If still don't try to start then check for compression and timing related problems.

Check for fuel to carb. Check for ignition by removing plug and laying metal case against cylinder head, pull starter and watch for spark. Check carb. Air filter and check exhaust port on muffler for dirt dobbers and carbon buildup. While plug is removed hold finger over spark plug port and see that you have a good bit of compression. If this does not help remove and replace or rebuild carb.

There are only 3 things necessary for ignition.
1. fuel
2. air
3. spark

Use a starting fluid spray directly into air filter.
if engine starts but doesn't run the problem is fuel'

remove the carburetor float bowl and then use a screwdriver to remove the jet locking nut in the tube the bowl nut attaches.
Use a small wire to remove the jet locking nut after it is loose. Then use the wire to remove the jet tube. Tube has several jet ports that should also be cleaned. reassemble. Allow carburetor bowl to refill then crank at full choke position. If the engine starts buy some techron fuel additive from an auto parts store and add 2-4 ounces to the gas for the next 2 tanks. this will completely clean the fuel system.

If engine doesn't start check for spark either using a spark tester or removing the spark plug and holding plug against the engine frame and pulling starter rope if spark is present replace the spark plug and try to restart the engine.

If these steps don't work I would replace the carburetor.

Try removing the fuel, remove the spark plug and give a few pulls to remove starter fluid from the cylinder, once completed attach your spark plug and check spark, reinstall plug, add fresf fuel to the tank and try staring with normal cold start procedure. Does it have good compression?

hello sir, my machine will only start when pumping primmer bulb or squirting fluid in the carburetor than stops. the fuel line has broken off, in most small carburetors this is a ongoing problem.old fuel will crystallize when left in tank for a long time.plugging up ports, fuel lines, small screen in carburetor.fuel lines will dissolve clogging carb.this is why it will run when the choke is on creating a vaccum to where there is fuel forced in the carb to rum,also the gas will evoporate leaving the oil behind clogging up carb.the thing to do is remove carb. and clean out,replaceing gaskets or fuel line if necessory.use carb cleaner to clean out carb.make sure to make note where fuel line go.the fuel filter broke off of fuel line letting debris get in carb plugging it up.the muffler is known to clog up a lot on these machines where thay want run. the compression should be 60 to 120 lbs any thing below 60 is junk. when adjusting the carb screws turn in all the way than turnout 1 1/4 turns turn in slow untail machine runs also you need to check for spark by removing plug and grounding aginst engine to chech spark, ok.a new spark plug would be a good ideal too , if you are going to make these repairs use new fuel line and filter,hope this helps,any comments welcome,thank you, ~~

Check that the carburettor and fuel lines are clean. If the unit has not been used for a while the gas (petrol) will evaporate leaving the oil behind to choke up the fuel system. Dirty fuel will do the same. When adding fuel use a funnel with gauze filter in it and always empty the fuel tank and then run the motor until it dies when you've finished work.

Abell, put a little drop of petrol in the plug hole, replace plug and give it a pull. If it fires up for a moment, it is a fuel starvation problem. Check the carb, clean and make sure the nedel valve in the bottom of the carb is not sticking. Good luck!

check that fule is getting into the engine and you have a good clean spark plug with a good spark on it and the air filter is clean
try tipping a cap full of fult (2 stroke mix) into the carb throte right into the engine then try to start it up,,if it spluters into life and stops the carb jets are blocked up or no fule is getting to the card

I use 50:1 with Sthil 2-stroke oil in ALL my 2-stroke equipment. This ratio does not smoke at all, and does not foul plugs.

Never had a problem yet. At this mix ratio, you can also use it in 4-stroke engines, which means you only need 1 fuel can on site. Also eliminates the possibility of using the wrong can to fill the trimmer.