1. Verify the Fuse:
* Type: Make absolutely sure you're replacing the fuse with the *correct amperage*. Check your owner's manual or the fuse box cover for the correct rating. Using a higher amperage fuse is dangerous and will likely lead to a fire.
* Location: Locate the blown fuse (check the under-hood fuse box and possibly an interior fuse box as well). Visually inspect the blown fuse – it should be clearly damaged (broken filament).
* Test (if possible): Use a fuse tester or multimeter to confirm the new fuse is good and the old one is definitely blown.
2. Investigate the Short:
This is the most crucial step. The short is the reason the fuse blows. Here's a systematic approach:
* Power to the Fuel Pump Relay: With the fuse replaced (temporarily), check for power at the fuel pump relay's input wire. You'll need a multimeter to do this. If there's no power at the relay's input, trace the wiring back from the relay to find the break in the circuit.
* Fuel Pump Relay: If the relay is receiving power, test the relay itself. You can swap it with a known good relay of the same type (from another circuit, if possible, for testing purposes only). A bad relay is a common cause. If it's the relay, replace it.
* Wiring Harness: The most likely culprit for the short is a damaged or corroded section of the wiring harness leading to or from the fuel pump. Carefully inspect the harness for any:
* Chafing: Wires rubbing against metal parts.
* Corrosion: Rust or other corrosion on the wires or connectors.
* Bare wires: Wires that have lost their insulation.
* Fuel Pump: While less likely, a shorted fuel pump can also cause the fuse to blow. However, this usually only happens *after* the short in the wiring has already been eliminated. Testing this involves disconnecting the fuel pump wiring and checking for continuity – this is best left to someone with experience working with automotive electrical systems, as it involves working with fuel which is both flammable and explosive.
3. Start Relay:
The starting relay problem is likely unrelated, but the problems may share a common cause (a low battery voltage, for instance). Verify the battery voltage is within spec (usually around 12.6 volts when the engine's off). A weak battery can cause all sorts of electrical gremlins.
4. Professional Help:
If you are uncomfortable working with automotive electrical systems, particularly with the fuel pump circuit, it's best to take your vehicle to a qualified mechanic. Incorrectly dealing with fuel system components can be dangerous.
Safety First: Always disconnect the negative battery cable before working on the electrical system to avoid accidental short circuits and injury.
By systematically checking each component and wiring, you should be able to pinpoint the cause of the short circuit and resolve the fuel pump issue. Remember safety is paramount.
