Trouble shooting suggestions-Thetford Toilet/water pump

It might be that the toilet fill valve is weak, and that RV pump pressure is greater then city pressure.

Thanks, Dr Quick.. that's a start.

I had a similar problem at the first of the season last year. After cycling the foot pedal about a dozen times it cleared up. Maybe some type of lubrication would help.

Yes the cross-over valve for flushing is still letting water through down to the black tank when "closed" so something is keeping it open a bit.

You need to scrape around some and use Silicone spray a lot to get the valve to close properly again.

It is probably the toilet valve. Purchase a good toilet chemical that has the properties of lubricating the valves, cleans the sensors as well as break down of waste. When you dump, pour some in your toilet and let it sit. This is so it will penetrate the rubber gasket and allow the valve to slide on it, fully closing. It the valve in the toilet does not close ALL the way the water valve on the side of the toilet won't close. Also, try some silicone on the spring after you clean it so cut down friction. If you are worried about the toilet overflowing, purchase an alarm available at Home Depot for about $9.00. You just set it on the floor and if there is water it emits a high frequency tone.

Thanks to all. I can see my Sunday to-do project. Will clean the gasket,
spray with silicone and will get the toilet chemical joelc recommended.
The water alarm is a great idea, too. Thanks, all.

Couple of things you might want to do based on my experience. First clean and lubricate the spring in back of the peddle with silicone. Get some good toilet chemical that not only breaks down waste but also cleans your sensors and LUBRICATES your valves. Pour some of this chemical in the toilet and let it set. This will lubricate the valve in the toilet. So, every time you change your chems just let the lubricant do the work on the valve. Also, if you don't have one and are handy, install a shut off valve so if the toilet does leak you can shut the water off. I also purchased a battery water alarm at Home Depot for about $9-$12. You put it on the floor and if the toilet does overflow an alarm goes off as soon as the floor gets a little wet.

SORRY. DID NOT NOTICE I RESPONDED BEFORE. LET US KNOW IF THE PROBLEM IS SOLVED.

There's a small screen in the cut-off valve supplying water to the toilet that tends to plug up with calcium from hard water. The same thing happens with the aerators/screens on the faucets. In the toilet shutoff valve those build ups usually prevent the valve from closing all the way so you get some leakage of water into the bowl. You just need to remove and clean or replace the shutoff valve.