A tap-to-feed head that releases all the line usually has a spool, cap, spring, or winding problem—not a motor problem. Use these checks to find the cause and decide whether to rewind, replace a part, or install a new head.
A tap-to-feed string trimmer head that dumps all the line usually has a problem with the spool, cap, spring, or line winding. Unplug the trimmer or remove its battery first, then inspect the head in the order below. Most causes can be checked without special tools.
Safety first
Turn off the trimmer and disconnect the power source before touching the head. For a gas trimmer, shut off the engine and allow hot parts to cool. Wear gloves when handling worn line or a damaged head, and follow the instructions for your specific trimmer.
1. Check the line size and type
Line that is too thin may slip out of the spool or fail to lock correctly in the feed mechanism. Line that is too thick can bind, prevent the spool from rotating properly, or overload the head.
Check the trimmer's manual or the marking on the spool for the correct diameter. Do not assume that any round line will work. Some heads require a specific range of line sizes, while some use twisted, square, or other shaped line.
Also check whether the head is designed for standard nylon line. Installing the wrong type of line can prevent the retaining features from holding it securely.
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2. Remove and inspect the spool
With the power disconnected, remove the bump knob or head cover and take out the spool. Look for:
Line wound over the spool's outer edge
Crossed or loose wraps
Line packed unevenly on one side
Cracks in the spool
A broken line-retaining notch
Melted or distorted plastic
Line wound in the wrong direction
The line should be wound tightly and evenly in the direction shown by the arrow on the spool. Leave enough clearance below the spool's outer rim for it to rotate freely. Secure the line in the spool's retaining notch before reinstalling it.
If the line is tangled, cut it off and rewind the spool rather than trying to force the tangled section back into place.
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3. Confirm that the spool and head are compatible
A replacement spool can look correct but still be the wrong part for the head. Compare its diameter, height, center opening, line-retaining slots, and feed direction with the original.
An incorrectly sized spool may sit too loosely inside the head. When the trimmer starts or the head is tapped, the spool can move enough to release the entire line charge. Use the replacement part specified for the exact trimmer and head assembly whenever possible.
4. Inspect the cap, bump knob, and spring
The cap or bump knob controls the spool's movement. If it is cracked, badly worn, cross-threaded, or not fully latched, the spool may not be held in position.
Check the spring underneath the spool as well. It should be straight, seated in its recess, and strong enough to press the spool against the cap. A missing, collapsed, or incorrectly installed spring can allow the spool to release line continuously.
Clean grass, dirt, and packed debris from the head. Debris can stop the cap from locking or keep the spool from returning to its normal position after a bump.
Do not operate the trimmer if the cap is loose or cracked. A head that cannot securely retain the spool can release parts or line while rotating.
5. Check the line ends and eyelets
Pull each line end gently through its eyelet. Both ends should move with controlled resistance, not slide out freely.
Inspect the eyelets for:
Missing or loose bushings
Sharp grooves caused by wear
Cracks around the openings
Melted plastic
Line caught behind the eyelet instead of passing through it
A worn eyelet can cut the line or allow it to pull through too easily. Some heads use replaceable eyelets; others require replacement of the complete head.
6. Reassemble the head correctly
Reinstall the spring, spool, line ends, and cap in the order shown in the manual. Make sure the line ends are aligned with the eyelets and that the cap clicks or threads fully into place.
After assembly, pull each line end lightly. The spool should not spill the line. Turn the head by hand to confirm that nothing rubs or binds. Then briefly run the trimmer at low speed in a clear area and observe the head from a safe distance.
Do not tap the head against a hard surface during the first check. Use the manufacturer's recommended bump-feed method and only the amount of line specified for the head.
7. Look for incorrect setup or excessive line length
Some heads feed when the bump knob is pressed against the ground. Others use a different release mechanism. If the head is assembled for the wrong operating method or the bump knob is held down, it may release more line than intended.
Check that the cutting blade on the guard is present and positioned correctly. That blade trims the line to its working length. Never bypass or remove it to compensate for a feeding problem.
If the line is repeatedly overfilled, reload it with the specified amount. Too many wraps can put constant pressure on the cap and prevent the spool from locking properly.
When to replace the spool or head
Replace the spool if its retaining notch, center hub, or outer walls are cracked or worn. A replacement spool is usually reasonable when the head itself is sound and the spring, cap, and eyelets still fit tightly.
Replace the complete head when the cap no longer locks, the spring seat is damaged, the eyelets are worn into the housing, or the head has melted or cracked. Choose a head that is compatible with the trimmer's shaft, mounting hardware, rotation direction, and approved line diameter.
If a correctly sized spool is wound in the proper direction and still dumps its line, the feed mechanism is likely worn or damaged. Stop using it until the retaining problem is corrected.
If the problem continues
Try one known-compatible spool loaded with the correct line. If that fixes the problem, the original spool or winding was at fault. If the new spool also releases all the line, inspect the cap, spring, eyelets, and head mounting assembly.
Do not continue operating a head that releases the complete spool of line. If you cannot identify the correct assembly or the head has structural damage, use the trimmer's parts diagram or ask a qualified repair professional to confirm the replacement.
FAQ
Why does my bump-feed trimmer release all the line at once?
The most common causes are incorrect line size, loose or uneven winding, a wrong replacement spool, a missing or weak spring, or a worn cap or eyelet. A cracked spool or head can also prevent the line from being retained.
Can I fix a tap-to-feed head by rewinding the line?
Yes, if the spool is undamaged. Remove tangled line, use the specified diameter and type, wind it tightly in the marked direction, avoid overfilling, and secure the line in the retaining notch before reassembly.
How do I know whether to replace the spool or the whole trimmer head?
Replace the spool when the spool or its retaining notch is damaged but the cap, spring, eyelets, and housing are sound. Replace the head when its cap, eyelets, spring seat, or housing is cracked, worn, or unable to hold the spool securely.
Is it safe to use a trimmer if the head keeps dumping line?
No. Disconnect the power and correct the retaining problem first. A loose spool, damaged cap, or cracked head can release parts or line while the head is rotating.
