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,

[Tom]

SDR,
A lot of folks started using a 16 amp fuse in that spot. Unless you have the rear window defrost, a 16 amp is adequate. That fuse protects ( used loosely ), the following; fuel pump - about 5 amps, heater fan - about 5 amps, rear window defroster Don't know the amps for this. and last the AAR - about 1 amp. So if you are not using or don't have a rear window defroster, your normal draw max would be about 11 amps. No reason a 16 amp would not be enough. If you have been running a 16 amp for some time and have no rear window defroster, you have something else going on. Putting a larger fuse in could lead to overheated wires on the circuit that is causing increased current flow.
The wires for the AAR are sized for about 10 amps max continuous. If the wire to the AAR starts to short to ground and causes increased current flow, this has happened to several members here, it can cause a fire in the ignition harness. With a 16 amp fuse being used and the fuel pump running, there is a better chance that the fuse will blow before a fire starts. Every member that had a fire caused by the AAR was using a 25 amp fuse. Had they been using a 16 amp, the outcome might have been different. The other thing that you can do is run a 25 amp but install a 5 amp in-line fuse where the AAR plugs into the harness wiring.
Tom