How to Start a Stubborn Weed Trimmer With a Thimble and Some Gas

Last Updated: December 23, 2021

Weed trimmers can be a pain to start at times, and when they start to get old, sometimes they need a little help to get some gas into the cylinder head. Some use starting fluid for this, but a small amount of gas can work as well, as explained in this article.

Steps

1
Make sure the gas tank on the trimmer is full before assuming it's not working properly. Do a quick check to satisfy yourself.^{[1]
X
Research source}
2
Take off the spark plug with a spark plug wrench.

Advertisement
3
Check the rim below the point of the spark plug for build-up of carbon deposits, and the point as well. The rim should be silver and not black, and the point should not have build-up on it either. If the rim needs to be cleaned, scrape off the deposits with steel wool or a use small flat head screwdriver. Be careful not to break the white ceramic insulator.^{[2]
X
Research source}
4
Make sure you are well clear of any gas and then heat the spark plug rim with a butane lighter.
5
Fill up a thimble with gas and put into the chamber, then put spark plug back on and tighten it on.
6
Put on the choke, prime three times, waiting 4 seconds between each prime.
7
Pull on the starter rope a couple of times until you hear the engine begin. It should rev up a little then stop because choke is still on.
8
Pull the rope again with choke off a few times and the engine should start.
- If the engine does not start, replace the spark plug with a new one, as this could be the problem. (The old spark plug has a number on it, so write it down before going to the store).
9
If it still does not start, it could be the carb is gunked with deposits, in which you will need at this point, some carb cleaner.^{[3]
X
Research source}
10
Clean the carb. To clean the carb, remove the carb cover and spray off the jets, making sure that they are clean and unobstructed.^{[4]
X
Research source}
- Then take off the primer cap from the line and spray carb cleaner down the tube where the cap was attached and replace the primer.
- Press a few times, forcing the carb cleaner in the line into the carb.
- Repeat this process a few times.
11
Check the spark arrestor screen, which can also be clogged. This is a screen that prevents hot particles from escaping the muffler, which can cause a fire. If it is blocked, remove it and scrape with a wire brush or a piece of wood, then replace it.^{[5]
X
Research source}
12
If the trimmer still does not start, it could be clogged, and may need a new carb. Also note whether after you have put a few drops of gas in the cylinder, and replaced the spark plug, it fires up for a little but does not run. If so, this could mean the carb is blocked, because gas is not getting from the carb to the cylinder, and the only thing that's making it run for a bit, is the little gas you put in the cylinder. If it does not run at all, it is usually because the spark plug is either spent or dirty.
13
Always empty all the gas out of the trimmer and all gas-powered equipment at the season's end. Press primer bulb a few times forcing excess gas in line to run into carb, and then pull starter rope a few times forcing all the gas out. Excess gas sitting in the line and in carb over the winter causes blockage, so always empty and clean when not in use for extended periods.

Community Q&A

Question

What can cause the trimmer to stall after pulling the trigger?

Community Answer

Bad air/fuel mixture. Dirty gas, often water in carb. Clogged muffler screen. Clogged air filter. Spool head could be binding from long weeds wrapped around.

Warnings

Don't try this if the engine has been running and hot. If you spill gas, it could ignite if it contacts the hot engine.

⧼thumbs_response⧽
Helpful 3 Not Helpful 6