There is a device that changes 115v house current to 12v current.
I have seen it in the JC Whitney catalog.
It is for use for 12v stuff you want to run in your house.
Such as radios, CBs, fans, coolers, etc.
Don't know if you could get one big enough to power a pump.

Check out the link below.

Pooh Bear

But it would be worth looking.

Something like this is easy to build.
Just need a transformer and a rectifier bridge.
You car alternator makes AC power and then changes it to DC.

Here is a link that might be useful: Power Inverters as JC Whitney

Might be cheaper to change the pump to a 120vac motor and get a remote car starter for the generator. If you really want to run that 12vdc pump motor, you may have to get a big honking 12 volt AC supply from a store that sells ham radio power supplies or try a ham fest flea market if you want one cheap. Just make sure it can deliver the current (amps).

Check this link out too:

http://www.mfjenterprises.com/products.php?prodid=MFJ-4245MV

Hope this helps.

SR

Here is a link that might be useful: Amateur Radio Power Supplies

Go to any walmart, kmart, or auto parts store and get an automotive battery charger. You can get a simple trickle charger for about $30.

A ham radio power supply would not be a good investment. Radio power supplies are designed to operate resistive loads but do not hold up well for inductive loads. (motors are inductive loads) In addition, Ham radio power supplies are very expensive.

I currently have 5 dentron 13.6vdc 35amp supplies and two Yaesu 13.6vdc 50amp supplies in my ham shack. The 35a units are $375 each and the 50amp yaesu's were $475.

Check out Home Power magazine for further options

Thank you everyone for information. We run a 6 bedroom house off solar, invertors and batteries in Baja 4 months a year but my husband doesn't mind investing into it and so far has not taken much interest in helping me with my log cabin. He is a wealth of information - and reads Power Mag, Home Power, Mother Earth, etc. Maybe when he has our home in Baja completed (our first one burned to the ground with 9 others), he will be more willing to invest some time and money into our log cabin retreat. In the meantime, it is MY project and I DO need to educate myself and read up on these things.

LazyPup, we are taking your suggestion. We are leaving for the cabin in a couple hours and taking a battery charger that we will plug into the generator whenever someone wants to shower and it is SUPPOSE to send the 110 from the generator and convert it to 12V (the pump for the shower) without even a battery inbetween. I will see how this application works for a temporary solution. (family reuion this week) By next year maybe I can have a more permanent solution so that the other family members using the cabin can operate it easily.

PoohBear - we do use JC Whitney for a number of supplies and they might be a good information source for me as well. I did call Mayberry where we bought the generator for information and a remote turn on switch which I hope to install next year. Thank you everyone.