This demonstration guide answers one field question about a bulb that will not rebound and keeps fuel flowing. Measurements come before parts, and the notes are not a generic equipment FAQ.
Diagnose before replacing parts
Start with bulb rebound and check-valve direction. That reading separates a bulb that will not rebound and keeps fuel flowing from adjacent faults that share the same complaint.
If the measurement is out of spec, treat the primer bulb as the primary path. If it is in spec, do not replace the primer bulb just to complete a parts list.
Repair the failed system
The usual correction is the primer bulb, installed to the documented spec for this complaint.
A demonstration shop records the finding so the next technician is not repeating a guess about a bulb that will not rebound and keeps fuel flowing.
Stop before you make it worse
Do not pumping the bulb until fuel drips from the carburetor. That shortcut hides the original measurement and creates a second failure.
If the machine still fails after the primer bulb is corrected, convert the visit to a broader diagnosis rather than stacking parts.
Written and published by Ridgeline Small Engine.