Why am I blowing both fuses for my aerator pump on my Ranger?

Thank you,

Chuck

It’s just too easy...

My Cajun blew the fuses when the livewell timer failed. I cut it out of the circuit and no more issues. I don’t have a auto timer anymore but the pumps work fine.

Because the circuit is drawing more amps than the fuse is rated for!
Have you witnessed this circuit work without blowing fuses? If so, what amp fuse was installed? Do you know this to be the correct rated fuse for that circuit?
You really need to plan on providing a lot more detail if you are to have any hope of assistance from the forum.

The aerator worked all day on Saturday. Back out on Sunday both fuses burned out? One is a 3 amp fuse the other is a 5.

3A is problematic for a pump due to start-up current. I even consider 5A to be as well. Many of our bass boats are wired with (mostly) 14 Ga. wire, and a few with 16 Ga. if they are really cutting corners. It is worth noting that the ABYC (American Boat & Yacht Club) E-11 Specification allows 16 Ga wire to be used for up to 10A circuits. It's also worth noting that yours WERE running with the 3A and 5A fuses. I'd feel you have a better match if you at least moved up to 7.5A fuses, and those aren't going to introduce any risk as long as your wiring is at least 16 Ga.

Still, I agree something obviously changed. Here are my thoughts:

1) You got trash in the pumps that's making them bind, sending the pump motor starting current through the roof. Try back-flushing the pumps with a garden hose running full blast. The goal is to get water flowing in reverse through the pumps to dislodge any [censored] binding them. Don't turn them on while doing this. Just try to get water into the plumbing from the outlet inside the livewell.

2) If both pumps are controlled by the same switch, look for a loose or corroded connection starting at where the +12V connects to the switch working backwards toward the battery. Any loose connection causes a voltage drop, and this will result in a load pulling more amps to get the same watts of power. This is true even if nothing about the pumps has changed, especially when you have the circuit fused with so little leeway.

3) Check the ground wires for the pumps (black). If they are connected together, look for loose/corroded connections as you work back toward the battery. Same story here - loose Ground can cause the same pumps to pull more amps.

4) Flip the aerator switch(es) on/off 20+ times. The switch has a "wiper" mechanism inside that can oxidize if not used frequently enough. Actuating the wiper will sometimes clean oxidation from the contact points.

5) Replace fuses with 7.5A fuses.

My Ranger has 5 amp fuses. Had this problem last weekend. Popped top of pump and it had some plastic in the impeller. Cleaned it out works fine now.

I keep forgetting that many pumps are now cartridge style! ....I guess it gives away how ancient I am. LOL

Popping the cartridge off is obviously the simplest thing to do if he has that style pump. I upgraded my pumps to the 750 gph, so they might be close on 5A. Not knowing which size pump he had is why I suggested 7.5A. It's still well under the amperage limit of the wire, so it won't allow any harm.