Ford 460 RV Fuel Pump No Power: Complete Electrical Troubleshooting Guide

The Quick Answer

Your 1994 National Dolphin with Ford 460 has lost power to the fuel pump due to a failed fuel pump relay or blown fuse in the fuel pump circuit. Since you confirmed the pump works when you ran a jumper wire directly to it, the pump itself is fine - the issue is in the electrical control system that sends power to the pump during normal operation. The most common culprits are the fuel pump relay (usually located in the engine compartment fuse/relay box) or a blown fuse, though it could also be related to the ignition switch or inertial fuel shutoff switch if your motorhome has one.

What's Causing This

In your 1994 Ford 460 engine, the fuel pump should receive power when you turn the key to the "on" position for a few seconds (prime cycle), then continuously when cranking and running. Since your pump worked fine with a direct jumper but has no power through the normal circuit, you're dealing with an electrical control issue rather than a mechanical pump failure.

The most likely causes are: a failed fuel pump relay (these commonly fail after 30 years), a blown fuse in the fuel pump circuit, corroded connections at the relay socket, or a faulty ignition switch that's not sending the signal to activate the fuel pump relay. Some Ford motorhomes also have an inertial fuel shutoff switch that could have tripped during your travels, though this is less common in 1994 models.

The fact that it happened suddenly after sitting for 4 days points strongly toward relay failure - relays often fail when they've been sitting in one position for a while, then are asked to operate again. The age of your motorhome makes this even more likely, as 30-year-old relays are well past their typical lifespan.

Tools You'll Need

• Digital multimeter or 12V test light
• Relay puller tool (or needle-nose pliers)
• Basic hand tools (screwdrivers, pliers)
• Replacement fuel pump relay (consult Ford parts specifications for correct part number)
• Replacement fuses (typically 15 amp for fuel pump circuit)
• Electrical contact cleaner
• Wire brush or sandpaper for cleaning connections
• Flashlight or headlamp for working in tight spaces

Step-by-Step Fix

Safety First: Disconnect the negative battery terminal before performing any electrical work or working with fuel system components to prevent sparks and potential fire hazards.

Step 1: Locate the fuse/relay box. In your 1994 National Dolphin with Ford 460, look for a black plastic box in the engine compartment, usually mounted on the driver's side fender well or firewall. It may be labeled "Power Distribution Box" or have Ford markings. Remove the cover - there should be a diagram on the underside showing relay and fuse positions.

Step 2: Identify the fuel pump relay. Look for a relay labeled "Fuel Pump," "FP," or "EEC Power." It's typically a small square or rectangular plastic component that plugs into a socket. If you can't find a diagram, look for relays that are identical in size and pin configuration and try swapping with a known good relay from another circuit.

Step 3: Test the relay. Pull out the fuel pump relay and examine it for obvious damage like cracked plastic or burnt terminals. Swap it with an identical relay from another circuit (like A/C) and try starting. If the engine starts normally with the swapped relay, you've found your problem. Replace the bad relay with a new one (about $10-15 at auto parts stores).

Step 4: Check fuses if relay swap doesn't work. Look for fuses labeled "Fuel Pump," "EEC," or "Engine." Use your multimeter or test light to check for power on both sides of the fuse. If there's power on one side but not the other, replace the blown fuse. If there's no power on either side, you have a wiring issue upstream.

Step 5: Clean connections and test. Before reassembling, clean the relay socket terminals with contact cleaner and a wire brush. Corrosion in the socket can prevent proper contact. Install the new relay firmly and test the system by turning the key to "on" - you should hear the fuel pump run for 2-3 seconds.

Step 6: Check for inertial switch if problem persists. Some Ford motorhomes have an inertial fuel shutoff switch, usually located in the cab area near the driver's feet or in a side compartment. Look for a small black or red button that may have popped out during travel. Press it back in if found and try starting again.

When to Call a Pro

Call a professional if you find that both the relay and fuses are good but there's still no power reaching the fuel pump. This indicates a more complex wiring issue that could involve the ignition switch, EEC-V module (computer), or damaged wiring harnesses that require diagnostic equipment to trace properly.

Also consider professional help if you're uncomfortable working with electrical systems or if you discover extensive corrosion in the fuse/relay box that suggests broader electrical problems. Since you're new to RVs and just bought this 30-year-old motorhome, it might be worth having a qualified RV or automotive electrician do a general electrical system inspection to identify other potential issues before they leave you stranded again.

The good news is that this is most likely a simple relay replacement (under $20 and 10 minutes of work), but if it turns out to be more complex wiring issues, repair costs could range from $150-400 depending on what needs to be replaced or repaired.