Homelite trimmer ut20769 does not run up to speed despite the throttle being wide open. Unit starts easily and idles well. Does seem to bog down alot. Thanks

Open, turn ccw, the high 'H' speed jet screw about .3 of a turn while holding the throttle wide open at the trigger. Engine should increase spread andyou may have to adjust. Failing that and assuming correct oil/gas mix it will likely be carburetion, clogged fuel filter or bad fuel line.

Turn adjusting screws in all the way "gently" until they seat. Not too hard or you will damage them. Turn out 1 1/4 turns on both will get you in the ballpark to start it up. If it starts, let it warm up without going to wide open throttle for an extended period. As it is idling, turn low speed screw in until it starts to want to die down, then turn back out a little at a time until it starts to bog down, then turn it back in to the center of the two bogs (at the highest point of RPM). Throttle it from idle to WOT and it should be a steady rise in acceleration without bogging down. If it does bog on acceleration, turn the Low speed screw counterclockwise 1/8 turn at a time until bog goes away. For the high speed it is critical that you don't lean it out too far. Hold the throttle at wide open and turn the screw counterclockwise until it appears to run really rich. (Blurbs like a four stroke). Then turn the screw back in while holding WOT (wide open throttle) until you get a smooth sound with a bit of blurb every couple of seconds. Hard to explain in type rather than showing it in person, but it will get you in the right direction. I'm wondering why you are trying to adjust the carb in the first place...... If there is an issue that makes you think an adjustment will fix it, try the method above. If the adjustments don't work, or you have to adjust them A LOT, you may be in the realm of a carburetor rebuild. Be sure to check the fuel line, fuel filter, and depending on what model saw you have, the carburetor boot for splits or cracks.

Try some carb. cleaner/ starter fluid on that spark plug right before you try to crank it. If that does it
replace your spark plug.

See if there is a Philips-head set screw on top of the carburetor (it is the idle speed adjusting screw) that you can turn counterclockwise backing off the idle (and possibly the wide-open throttle) speed. This is the simplest solution for you unless you wish to remove, disassemble and inspect the carb. Also, check the throttle cable to the carb, make sure it is not hanging up or binding near the engine where it connects onto the throttle plate shaft of the carb.

adjust the high speed screw first with the throttle at full speed, then adjust the idle screw to maintain idle speed

Its sounds like it is running rich. Adjust your high speed adjustment screw. If the unit is older think about buying a carb rebuild kit, they run about $12.00 at your local fix it shop and if you are not in a hurry online for about $8.00 give or take S/H.

close to the carb you will find two tiny screws. They are labeled H and L. L sets the idle speed. H sets the max RPM. Hold the throttle wide open and turn the H screw. When you find the very top end, back it down some or it will be running too lean. That would make it run hot, and provides less lubrication. Could result in engine failure if you run it too lean.

you need to make sure there is not a fuel restriction first check the fuel filter, then the lines. If these seem ok then adjust the High speed rpm, there should be two adjusters one for High speed one for low speed(when the throttle is fully engaged.Do small adjustments at a time.

Hello cosorio70:

You can Get a Manual from the Following Site Addy;
https://register.homelite.com/contact_us/new and Fill Out the Required Information. Remember to have the UT Number if this Unit has One.
>>The Following is the Instruction File for Setting the Air Mixture Screws. Any Input is Appreciated. The Procedure is the Same for 1 or 2 Mixture Screws, Just Use the Instruction File and Skip Over the Section with the Missing Mixture Screw ( Usually the H Mixture Screw).
>>Now Setting the Air Mixture Screws:
>>****Turn the Idle Air (L) and Main Air (H) Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Set the Throttle Full Open, Start the Engine.
>>Turn the Main Air (H) Mixture Screw Clockwise Until Proper Revs are Obtained. **Carefully Use your Finger and Move the Governor Arm to Rev the Engine (on Chainsaws and Trimmers Use the Trigger to Rev the Engine) Until you Reach Max RPMs (on Chainsaws and Trimmers, the RPMs are Not Set to MAX. Set to Max and then Reverse the Setting Screw 1/4 or 1/2 Turn. If the H Mixture Screw is Set too High; the Engine will be Starved for the Oil in the Gas and Damage the Piston and Jug/Cylinder) and the Engine is Running Proper at Full Throttle Up a Grade and for Chainsaws and Trimmers they Do Not Bog DOwn Under a Load. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs.**
>>Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required.
>>Now Set the Idle Air (L) Mixture Screw so there is No Hesitation when Rapidly Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.****
Please, Do Not Hesitate, If I Missed Something or you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance.
Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Be Happy. Thanks.

Good Luck

Respectfully

jbridger (John)

I have let my leaf blower run and warm up before throttling up and still it bogs down and shuts down. There is no air cleaner to clean should I just blow out the carb. and fuel lines?
It runs and idles just no high speed to blow.