914 Fuel Pump fuse on relay board blows Options

[Sea Dragon 914]

Does anyone know what are common causes of blowing the fuse on the engine relay board for the fuel pump and how to diagnose it? Would a bad fuel pump cause this?

Thanks,

[euro911]

The low-rating fuse is the probable cause, but check the path for corroded connections as well. Corrosion on terminals will cause a higher current draw in a circuit.

[screenguy914]

The low-rating fuse is the probable cause, but check the path for corroded connections as well. Corrosion on terminals will cause a higher current draw in a circuit.

To be most correct, if voltage is constant, additional circuit resistance decreases, not increases current flow. Same with faulty ground connections.

Except for a partial or complete short to ground (via circuit path or a malfunction in the load itself, bulb, motor, heating element, etc.), circuit current is a result of the total current requirements of the load(s) in the circuit and how the circuit path is wired.

However, if a circuit connection point, e.g. splice, connector, etc. has excessive resistance due to corrosion or bad contact, that will 1. reduce voltage and thus current available to operate the load and 2. Create resistance and thus heat at that location. If the loads normally have high current needs (e.g. motors, heating elements, etc.), heat will be created at the point of excessive resistance.

I suggest isolating the branch circuit(s) by disconnecting the source wires for each of the loads until the offending load is identified.

Oops. Looks like you found the source of the excessive current draw. Congrats on your diagnosis and discovery and suggestions from others.

Sherwood