Bunn omatic won't make full pot-even with water line hooked up

One of 2 things. The water refill valve or high water probe is bad

Check the thermostat on the machine, make sure pot is full before brewing. The water in the tank just heats up it is loosing most of it, make sure lid is on pour in screen.

More than likely could be a bad timer.Check the time of the brew cycle is consistant each time.See if the sprayhead is in place.You may also try rodding out the brew tube with a de-liming spring p.n. 1111.0000.

I recommend slowly pouring in about a half a pot of cold water without coffee in the filter basket 5 or so minutes before you brew in the morning. There are 2 good reasons to do this-
1. Overnight you are having some evaporation due to the fact that your Bunn brewer has a reservoir that keeps a couple of pots worth of water at brewing temperature... a better temp than most "home" model brewers. This will top off the reservoir and you will not "short pot" except for the amount that the grounds themselves hold back.
2. Also overnight, due to the fact that the water is kept hot, the oxygen can dissipate from the water in the tank. Topping off with fresh water will mean a fresher first pot.
The Bunn brewers have a low wattage/keep warm heater so the actual heating element isn't doing all of the work over those long periods... it only kicks on when the temperature in the reservoir drops considerably (like after brewing). Be sure to let the brewer heat back up before brewing (you will hear it stop heating)
Hope this helps.

Try running a quarter-pot 50/50 solution of white vinegar and cold water through to clean out calcium deposits in the pump system. Use a clean filter to catch the pumped debris. When pumped through, let cool somewhat, and reuse the cold mixture again twice more. Pour out the vinegar solution and run several cold water loads through to wash out the taste. Hope this helps!

It sounds like there is some build up in the brew line, find the nearest bunn dealer and get a delimming spring, then remove the shower and run spring through brew line.

What's happening is that it isn't leaking, it's boiling over. You need to turn down the thermostat under the top lid. Also, before you brew coffee, add water to the tank and let it pour into an empty pot. Once it stops brewing, let it heat up for a few minutes then make your pot of coffee.

Check out:

http://whles.com/General%20Mtx%20Knowledge%20%20Tony%20Roach/BunnOMatic%20F35%20F20%20F15%20x.pdf

This is the free full service manual F15, F20 & F35 complete with troubleshooting section at the rear. This section has easy, plain english steps to follow to solve this very problem (others, too).

Good luck!

Most likely it is your tank heater, but look on the top of the tank heater, because sometimes the wire will burn off the top of the element