1996 Sportster Auto Bilge not working

[Toronto Dave]

I picked up a previously enjoyed 1996 Sportster that I have now got running but the Auto Bilge Feature does not work. Original pump was seized and the 3 amp fuse blown. I replaced both and it now works via the dash switch and also comes on for about 10 seconds when the battery is connected and shuts off. I can't find the exact wiring diagram but assume the dash switch turns the pump on directly and the MPEM turns it on via the relay embedded in the remote fuse block. When the battery is connected and dash switch is off I can feel the relay energize and the pump run so believe the relay is good. The water sensor checks out ok (open when dry and closed when immersed in water). I have also bypassed it at the plug and still no auto pump. What am I missing?

 

[JeremyD615]

Is it an OEM or an aftermarket bilge pump? Most of the aftermarket pumps have a float or a water sensor built into them and bypass the factory electronics other than the switches leg from the dash switch. Otherwise, it may be easier/cheaper to just throw an aftermarket pump in. They’re cheap and only take a few minutes to install/wire.

 

[Toronto Dave]

It is aftermarket but looks identical to original. 2 wires and no switch.

The previous owner missed the seized bilge pump and blown 3 amp fuse so then added another pump much higher in the bilge with a manual switch only wired directly to battery with a net result of melted stator, stator harness and starter. Water sensor was also unplugged. I turned motor on end and replaced all the melted and corroded stuff and got it running. Fortunately water never got into the motor. I may just go after market pump as suggested but as even the water senor checks out I want to be sure I am not missing something simple that got miss wired. I cant find any info on the water sensor circuit. Perhaps it goes through the MPEM and something is wrong on that end although is does come on for the first ten seconds or so when power is applied and also via the dash switch.

 

[Paul-at-theTub]

I have a 1997 Sportster and found that the auto bilge only works with the key thing on.

The bilge switch at the helm will run without the key but the auto feature only works with the key in. Not ideal as I now leave the key in when docking overnight (as you are not supposed to keep in water). Not ideal... Choice of someone stealing it or sinking if fills with water!

 

[Toronto Dave]

It seems to be resolved. It appears I fixed it by replacing the seized pump and blown fuse after all but just had the wrong expectations. It takes a good 60 seconds after the water sensor trips before the pump runs. I assume the MPEM does this to avoid it running when it gets a short splash on the sensor. Once the pump runs and the sensor goes open again the pump runs for another 45 seconds or so and then stops. In my previous boating experiences once the bilge switch trips the pumps runs instantly and stops as soon as the switch deactivates.

Paul at the Tub this is without the DESS key so perhaps the 97 is different.

 

[Paul-at-theTub]

Thanks Toronto Dave, I will see if I can figure out why because auto-bilge without DESS key would be my preference all the time even if it drained the battery (because otherwise what is the alternative)?

 

[yacht1255]

Thank you very much