1parkpointer

We need help! Our oil furnace stopped running two days ago. I noticed the fuel tank sight gauge down to the bottom of the tank. I unscrewed the sight gauge plastic from the top of the tank and found the bobber resting on the bottom of the tank. It sure was empty. We couldn't afford to fill the tank, so we only had the oil supplier put in 100 gallons. That was yesterday afternoon sometime. When I got home, the furnace would not start.
I opened the access door to the furnace, then loosened the feed line to the burner unit and discovered that there wasn't any oil in the feed line, so I re-tightened it. Back at the oil tank, I found the bobber in the sight gauge on the oil tank was resting at the bottom. I unscrewed the sight gauge and checked the bobber and found that it came up out of the oil, but when I let it go, it sank to the bottom indicating an empty tank. So now I see the bobber is not working any longer. There was oil in the tank, about 1/3 full.
I then loosened the top screw on the oil filter unit at the tank to find it wet, but nothing flowing out. After about a minute, fuel oil started to appear in the hole, so I reinstalled and tightened the screw. The oil furnace line runs through a pipe embedded in the basement floor and comes back out near the furnace. Shortly after coming out of the floor, the line goes to a 'T' fitting. I was only able to loosen the line coming down from the furnace, and found fuel oil dripped past the threads, so I retightened that fitting. From the 'T' fitting the oil feed line goes up about 1.5 feet and then makes two loops then goes up about 6-inches more and then passes through a hole on the furnace side about two feet above the floor. After previously opening all of the lines at those fittings, I re-loosened the fuel line at the burner unit and again found no fuel oil in that part of the fuel line.
Where do I go from here? Does the line need to be primed somehow? And if so, could someone explain how I do that?

SULTINI

When the tank runs out and you refill it sometimes a lot of sludge from the bottom when disturbed will enter the filter and block the filter and flow.
You should remove the filter replace with like and kind, fill the filter housing with oil put all back together and try restart.

Note; Usually the suction fuel line is off the bottom of the tank a couple inches.

1parkpointer

Found a combination of several air-blockage/fuel/air-blockage throughout the feed line to the furnace to be the main culprit. Wasn't getting good results at the bleeder at the pump side of the burner. After several resets and bleeding attempts this evening, finally was able to get all of the air bubbles out of the line and the fuel only flowed fine. The furnace is running and we'll shut it down this weekend to clean out the filter and/or replace it.
Thanks to everyone who took time to read this thread and to Sultini for offering the filter fix! Thanks again!

yuri

Replace the nozzle ASAP. Every time a tank runs out of oil the nozzle needs replacing or it will drip into the combustion chamber or not spray properly. Sometimes the screen on the side of the pump needs removing and cleaning. ALL kinds of crud gets into the pump and nozzle when the tank runs dry.