Fuel Pump Fuse Keeps Blowing? Here’s Why and How to Fix It
The bottom line: If your fuel pump fuse keeps blowing, the problem is almost never the fuse itself. The fuse is a safety device designed to blow when the circuit draws too much current. Replacing the fuse without fixing the root cause will only lead to another blown fuse—and in some cases, could cause a fire. The most common reasons are a failing fuel pump that draws excessive amperage, a short circuit in the wiring, or a clogged fuel filter forcing the pump to work harder.
What Happens When the Fuel Pump Fuse Blows
When the fuse blows, the fuel pump loses power. This means your engine won't get fuel. If you are driving, the engine will sputter and stall as if it ran out of gas, even though the fuel gauge shows there is still fuel in the tank. If you try to start the car, it may crank but not fire up.
The Most Common Causes (Ranked by Likelihood)
1. A Failing Fuel Pump Drawing Too Much Current
This is the number one culprit. Over time, the fuel pump motor wears out. Bearings get rough, brushes wear down, and internal friction increases. When the pump has to work harder mechanically, it draws more electrical current. Eventually, the current exceeds the fuse rating, and the fuse blows.
A fuel pump that is failing due to age or contamination will often pull 20 amps or more when the circuit is only designed for 15 amps. In one documented case, a fuel pump that should have drawn no more than 9 amps was pulling 22.7 amps—enough to blow a 15-amp fuse repeatedly.
2. Short Circuit or Grounding Issue in the Wiring
A short circuit happens when a live wire touches a ground point or another wire. This creates a path of very low resistance, which allows a massive surge of current to flow. The fuse blows instantly to protect the wiring from melting.
This can happen if the insulation on the wires gets rubbed through, if wires are pinched during a repair, or if rodents chew through the wiring. Water or moisture in the fuel system can also cause a short.
3. Clogged Fuel Filter or Restricted Fuel Lines
If the fuel filter is clogged, or if the fuel lines are kinked or pinched, the fuel pump has to work much harder to push fuel through the system. This mechanical resistance translates directly into higher electrical current draw. The pump may pull enough current to blow the fuse.
A clogged filter alone might not blow a fuse on a brand-new pump, but it can push an older, worn pump over the edge.
4. Bad Fuel Pump Relay
The relay controls the power supply to the fuel pump. If the relay’s internal contacts weld shut or fail in the "on" position, the pump may run continuously or receive erratic voltage. This can cause the pump to draw more current than normal, blowing the fuse.
A stuck relay is often noticeable because you can hear the fuel pump running as soon as you turn the key to the "ON" position, even before you try to start the engine.
5. Incorrect Fuse Rating
If someone before you installed a fuse with a lower amperage rating than the factory specification, it will blow under normal operating conditions. Always check your owner’s manual for the correct fuse rating. A typical fuel pump fuse is 15 to 20 amps.
Never install a fuse with a higher amperage rating than specified. This is dangerous. The fuse is designed to be the weakest link in the circuit. If you use a bigger fuse, the wiring itself becomes the weakest link, which can melt, short out, and cause a fire.
6. Contaminated Fuel
Dirt, rust, or water in the fuel tank can cause the pump to bind internally. The pump motor has to work harder to overcome the resistance caused by debris. This increases current draw and can lead to a blown fuse.
How to Diagnose the Problem Step by Step
You will need a multimeter and some patience. Here is a systematic approach.
Step 1: Check the Fuse and the Fuse Holder. Before replacing the fuse, inspect the fuse holder. Look for signs of melting, corrosion, or a loose fit. If the holder is damaged, it can cause poor contact and overheating, which will blow fuses.
Step 2: Measure the Current Draw of the Fuel Pump. Remove the blown fuse and connect a multimeter set to measure amps (DC current) in its place. Turn the ignition on (or start the engine if possible) and read the current. A typical fuel pump should draw between 5 and 12 amps during normal operation. If the reading is above 15 amps (for a 15-amp fuse circuit), the pump is drawing too much current.
Step 3: Check for a Short Circuit. If the current draw is normal, the problem is likely a short circuit in the wiring. Inspect the entire length of the wiring from the fuse box to the fuel pump. Look for chafed insulation, exposed wires, or signs of corrosion. A multimeter set to the continuity or resistance setting can help you find a short to ground.
Step 4: Test the Fuel Pump Relay. Swap the fuel pump relay with an identical relay from another circuit in the fuse box (like the horn relay). If the problem stops, the relay was faulty.
Step 5: Check the Fuel Filter. If the current draw is high but the pump is relatively new, the fuel filter is likely clogged. Replace the filter and see if the current drops back to normal.
Why You Should Never Drive with a Blown Fuse
A blown fuse is a warning sign. If you keep replacing it without fixing the underlying problem, you risk turning a minor electrical issue into a major fire hazard. The wiring in the fuel pump circuit is sized for a specific current. If the pump is drawing too much current, the wiring will overheat. The insulation can melt, leading to a short circuit and potentially a fire in the engine bay or under the dashboard.
The Right Way to Fix It
If the diagnosis points to a failing fuel pump, the only reliable fix is to replace the pump. It is also a good idea to replace the fuel filter at the same time, since a clogged filter may have contributed to the pump failure. If the wiring is damaged, repair or replace the affected section of the harness.
Recommended Fuel Pump Replacement: Choose KEMSO for Long-Term Reliability
When it comes time to replace your fuel pump, you want a part that is built to last and won't let you down. That is why we recommend KEMSO fuel pumps.
KEMSO fuel pumps are high-performance, direct OEM replacement units. They are designed to meet or exceed the original factory specifications, which means they will draw the correct amount of current and keep your fuse from blowing. Every KEMSO fuel pump comes with a lifetime warranty, so you can be confident in your purchase.
Whether you drive a car, truck, motorcycle, or powersports vehicle, KEMSO has a fuel pump that fits your needs. Visit the KEMSO website to find the exact pump for your vehicle:
👉 https://www.kemsoracing.com/
Final Thoughts
A repeatedly blowing fuel pump fuse is not a mystery. In most cases, it is caused by a worn-out fuel pump, a short in the wiring, or a clogged fuel filter. Diagnose the problem systematically, replace the faulty component, and always use the correct fuse rating. Your car will thank you with reliable starts and safe operation.
For more information on fuel pump replacements and to find the right part for your vehicle, check out KEMSO Racing at https://www.kemsoracing.com/.