Fyrer is letting the oil get too cold before burners kick on

Garnet, I am wondering if something is causing the oil to "gel".
I remember years ago that #1 & #2 oil was mixed in cold weather to be thin enough to flow properly so the burner would work. If cold weather is not a factor, then I would suspicion that the oil is not good quality, thus causing you problems of clogging. Are you sure that there is no water from condensation in the tank? Additives might help to clear the situation.

https://www.manualslib.com/products/Cecilware-Fmp-40hp-477182.html

see the following steps:
f the burner doesn't run, set the thermostat a few degrees higher than normal to see if it comes on. If it still doesn't come on, check switches, and breakers and fuses (see the Electrical Service Panel Fix-It Guide). If the unit has a reset button, press it. Also oil the motor at any oil ports (see below). If the unit doesn't want to start and run, first check the c to make sure that the ignition is getting power. If there is power, check the built-in safety controls (see below) that may turn the system off if they perceive problems.
If the burner cycles too often, replace the filter (see below). Also, oil and adjust the blower (see the Forced-Air Distribution Fix-It Guide).
If the burner runs but won't fire, make sure the oil valves are open and that there's oil in the tank. Check the tank level with a clean stick.
If the burner smokes or squeals, shut off the unit, let it cool, and fill the oil cups. Recheck them after the motor has run for an hour.
If the chimney smokes even after the flue has warmed up, the unit is wasting fuel; call for professional repair.
Safety Controls
Oil furnaces and other heat systems include safety devices that monitor operation and turn off the unit if something goes wrong. In some cases, the safety device can be the problem.
If you encounter an operating problem with an oil furnace, first reset the safety and try again.
If the burner kicks off again, shut off all power at the electrical service panel ; the burner motor and ignition may be protected by separate fuses or breakers.
If the sensor has a photocell, wipe it with a clean rag or tissue and see if the furnace starts.
If the safety is a stack switch mounted on the flue, remove the screw holding the unit to the stack, slide it out, and wipe off the sensor.
If the furnace won't start after three tries, seek professional assistance. Unburned oil can accumulate in the combustion chamber and "flash back."

We need to get a few details cleared up:

Is it the Furnace (Oil burner) that is running, (on idle you called it..)
or is it the FAN that is running?
What are you tapping, that shuts off what?
Is the fan that blows the air around the home shutting off, or the burner?
(When the burner is running, there is a loud roar!-- the fan should be much quieter..)

If it is the fan that is running,-- I might ask, is the air coming from the registers too cold?-- for with the fan running, you are getting all the heat from the oil that was burned. But naturally, you don't want it to be uncomfortable.. So-- you can open the cover on that Fan control switch, and raise the temperature at which the fan turns ON and OFF..

Let us know what you find.

Mack B

The first thing I would check is spark on the electrodes in the burner, if you pull the transformer down from the bottom of the burner you will see two springs that touch metal poles in the bottom. You are going to have to have someone else run the machine in cold water mode (these machines will create spark in cold or hot water mode) and holding onto a long insulated screwdriver you are going to get about 1/4 inch away from each of the springs and see if a spark comes across the spring and the screw driver. Be very careful in doing this, you are playing with a lot of power. If no spark then this would indicate that you have a fuse blown or the transformer is bad. You would then proceed in checking power to the transformer. If you are getting spark then it is going to be one of the safety systems that is giving you a problem. Let me know what you find out.

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Hi check the air filter is clean try jumping out the pressure switch see if it lights clean the flame sensor as well

There should be an air adjustment collar on the oil pump side of the burner. Give it a bit more air. Have you replaced the oil filter and oil pump strainer? Flip open the transformer on the top of the oil burner and look for a small black round cylinder. This is your Cad cell eye. Take a paper towel and polish the end that looks down the burner tube. You did not mention how long the unit fires prior to shutting down, could be a bad primary control.

Replace both coils on the burner valve . After heating up , they will not open to let gas thru again until cooled down for a short period of time . With no heat , timer will not cut off unless set for timed dry .

i have a reillo oil burner that fires up from cold no problem reaches the set temp and cuts out, when it tries to kick back in it keeps clicking the lockout light is not coming on and the fan is still running any ideas?