oil furnaces kicks reset

Iv been working on two furnaces and both are doing the same thing. Iv replaced the nozzels, filters checked both tanks for water. checked for air in fule line, and Im lost. Both will start and run fine for a day or two then kick the reset out. One furnace is 7 years old and the other one is 6 mounths old. Both started doing this about the same time after they got fuel delivered. One is the new style becket controles and the other is the old style. Both have good oil pressur at the pump, the older furnace has a two line system and the new one has a one line system. Iv taken fule from the bleeders at the pumps and no water or durt was found. The intake line is 3 to 4 in off the bottem of the tanks. Both burners are burning clean and I cant find a problem. They will run from 12 to 48 houres then kick the reset. Please Help, Rich

 

Was a smoke/draft, and temp test been done?

 

Do these heaters have cad cells for flame detection or stack switches? Make & model of the furnaces(?) & burners would be helpful (particularly the burners).

 

Both have cad cells, and a skoke test was done and air adjusted.

 

I changed nozzels again tonight one is running "so far" , the other quit before I got home.

 

You need to service both fuel systems. Replace any filters, replace the pump screens, & flush at least a quart of fuel thru the system (including the drawer assembly) then replace the nozzles.

 

Iv changed the fuel filter twice and the nozzels three times and bled a 1/2 gal of fuel at the pump each time befor changing the nozzel. I belive you are right, one is running ok the other is shuting off yet. Iv never had this much trouble before with dirty fuel, but it cant be anything else. Thanks Rich.

 

If you haven't changed the screens in the pumps, if they are Suntec pumps, do so. I'd bet you find they are quite dirty.

 

Thanks, Ill check that tomarrow. I did overlook that screen. Rich

 

Danfos & Riello pumps also have screens but Webster does not. Suntec is by far the most commonly used pump out there. Let me know what you find.