What Causes a Golf Cart to Surge

Does your golf cart lurch, buck, or pulse at steady throttle? Surging usually traces to battery, throttle, motor or controller faults—or gas-side ignition and carb issues.

Why Golf Carts Surge

Surging is that on-off, stop-go sensation when you hold the pedal steady yet speed keeps rising and falling. It’s almost always an electrical delivery or fuel/air delivery problem. Because golf carts come in electric and gas configurations, you’ll diagnose them differently, but the logic is the same: confirm clean power or fuel, valid throttle input, and a healthy drive unit (motor or engine) governed by a controller or carburetor that isn’t “hunting.”

Electric Golf Cart: Common Causes

• Battery pack (health and connections): Weak cells or uneven state of charge cause voltage sag under load, which the controller “sees” as low power, then recovers—producing a surge cycle. Look for corroded lugs, loose cables, swollen cases, or packs that drop below spec under acceleration.
• Throttle/accelerator pedal sensor: Faulty ITS/MCOR or Hall-effect sensors send jittery signals; the controller responds by adding/removing power in pulses.
• Motor: Worn brushes, dirty commutators, or a failing speed sensor (on carts that use one) interrupt smooth torque delivery and can feel like surging at mid-speed.
• Controller: A deteriorating speed controller, poor grounds, or overheated MOSFETs can “current limit,” cool, then re-apply—classic surge behavior.

Gas Golf Cart: Common Causes

• Spark plug / ignition system: Worn plugs, cracked boots, weak coils, or intermittent ignition modules misfire under load, then relight—felt as a rhythmic surge.
• Carburetor and fuel path: Clogged main jet, low float level, varnish in passages, dirty fuel filter, or vacuum leaks make the mixture lean and inconsistent, so the engine “hunts.” A sticking governor cable can mimic the same symptom.

Symptoms Checklist

• Only under acceleration → think battery voltage sag (electric) or fuel starvation (gas).
• Only at steady cruise → suspect throttle sensor jitter, controller hunting, or carburetor mixture oscillation.
• Hot-only symptoms → thermal limits in controllers/coils, vapor lock, or high resistance connections.

Step-by-Step Troubleshooting (Both Types)

1. Battery inspection (electric): Measure pack and individual battery voltages at rest and under load. Clean every terminal to shiny metal; tighten to spec. Replace any battery with abnormal drop. Balance charge the pack.
2. Throttle/pedal (electric): Check pedal travel and linkage. Test the throttle sensor output (smooth, linear voltage/ohm sweep). Recalibrate or replace if the signal jumps or drops.
3. Motor (electric): Inspect brushes for length and spring tension; clean the commutator. Verify the speed sensor connector and cable are intact and seated.
4. Controller (electric): Confirm clean grounds, adequate pack voltage, and proper cooling. If possible, read fault codes; a bench test or known-good swap can confirm failure.
5. Spark/ignition (gas): Replace the spark plug (correct heat range and gap), inspect coil and leads, and verify the kill-switch circuit isn’t intermittently grounding.
6. Carburetor (gas): Replace fuel filter; check lines for kinks. Clean jets and passages with proper solvent, set float height, and check for vacuum leaks at the intake boot.

Targeted Fixes by Subsystem

Electric: Battery

Load-test each battery; any cell that collapses under pedal input will make the cart surge. Replace in matched sets to keep the pack balanced.

Electric: Throttle/Pedal

A jumpy sensor equals jumpy speed. If the output isn’t smooth through the entire pedal sweep, calibrate or replace the sensor module.

Electric: Motor

Brushes shorter than spec, glazed commutators, or a failing speed sensor produce intermittent torque. Service brushes and clean the commutator; replace the sensor if open or erratic.

Electric: Controller

Overheating or failing power stages limit current then restore it, creating a surge rhythm. Improve cooling, verify grounds, and replace the controller if diagnostic codes point that way.

Gas: Spark Plug/Ignition

Swap in a new plug first—it’s fast and cheap. If surging persists, test the coil’s resistance and inspect the module; intermittent spark is a classic culprit.

Gas: Carburetor

Disassemble and clean. Ensure the main jet is clear, float height correct, and idle mixture within spec. Replace brittle gaskets and cracked vacuum hoses.

Preventive Maintenance to Stop Surging

• Quarterly: Clean and torque battery terminals (electric); replace fuel filter (gas).
• Biannually: Inspect throttle linkage/cables, pedal bushings, and governor cables for binding.
• Annually: Service motor brushes/commutator (electric) or the carburetor and ignition (gas). Update controller firmware if applicable.
• Always: Keep tires at equal pressure and brakes correctly adjusted—drag can masquerade as surging.

Conclusion

Surging is a symptom, not a mystery. Verify clean, stable power (or fuel), confirm a smooth throttle signal, then validate the drive unit and its governor—controller on electric, carb/ignition on gas. Work methodically and your cart will return to steady, predictable acceleration.