My kerosene mpi monitor 40 will come on and the burner will lite for about ten minutes at a time, then it will cut off for no reason

Here is some information and your Service Manual with a Troubleshooting section.

Monitor 422 Kerosene Heater

cleanflametrap.com http://cleanflametrap.com > bruce_monitor

Monitor 422 · The Monitor is a computerized kerosene heater. · Here's an odd accumulation at the burner base. · Here the top panel is ajar and the upper front ..
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Monitor 422 Service Manual - ManualsLib

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View and Download Monitor 422 service manual online. MONiTOR HEATING SYSTEMS. 422 heating system pdf manual download. Also for: 22, 21, 41, 441, 40.
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It sounds like there may be an issue with the circuit board on your MPI monitor 41 kerosene heater. Based on your description, it appears that you've recently replaced the circuit board, but you're not able to get power to the front panel, despite power showing in the wiring.
There could be multiple reasons for this, and it is essential to investigate further. Here are some things you can check next:

• Make sure that all connections are secure and properly connected
• Make sure that the circuit board is the correct one for your heater model
• Check the wiring, it could be loose or damaged
• Check the fuses, they might have blown
• Check the thermostat, it could be faulty or not connected properly.

If you have checked all these things and the issue persists, it's best to call for professional help as it may require specialized knowledge and skills to troubleshoot and fix the problem. It's important to note that working on heating appliances can be dangerous, and only qualified and licensed personnel should work on them.

https://www.manualslib.com/manual/875029/Monitor-422.html?page=49#manual

I would check all fuel lines, connections, and watch how long it takes to ignite. Kerosene heaters should atomize fuel meaning it should look like a fog not droplets, so that would point to fuel nozzle problems. That being said it should exhaust out side not in to the house, inspect the burning chamber real good for cracks or leakage? If this unit has a flue or damper make sure it has a good draft to exhaust the burnt fuel. This is purely speculation not a solution, these are things I would be looking for if it were in my home. Good luck

First thing to do is clean the flame rod. Take the black grill off of the front of the heater (6 ro 7 screws). Now locate the flame rod. It is beside the window where you can look into the burner. It has one wire going to it. Be careful so you don't damage the gasket. The rod goes in then straight down, so you will have to turn it to get it out. You can clean it with some steelwool or emory cloth. Reinstall it and try the heater.
Listen to the heater. If it cuts off, does the fuel pump start making a thumping before the heater cuts off? If it does, the heater is running out of fuel for some reason. I know you checked the filter, but did you check the strainer in the fuel sump. You can find it on the right side of the heater at the bottom. Make sure you turn off the fuel at the barrel before you remove it and have some rags ready to soak up the kerosene that will come out. Clean the filter with some kerosene if it needs it.
Let me know what you find and don't forget to rate my answer. Thanks.

Your problem may be a dirty flame sensor which can be cleaned with some steelwool. If the heater makes a ticking or thumping noise before it cuts off it is not getting fuel to the pump and you would need to check your filter and also the strainer in the fuel sump. Make sure you don't have water in your kerosene either. You can find an owner's manual at www.monitorproducts.com which will give you some more info.

I recently relocated monitor heater from living room to dining room and ran new line to heater. I have pressed the priming button located on right side and turn unit on, but all that happens is it will click on run for a cycle and burner never ignites and then turns itself off and burner indicator lights continue to blink on and off, I dont think it is getting proper fuel to unit. What do I need to do?

I had the same problem last night and this morning. Its in the manual. I had to take the fan off of the back and vaccuum out all of the dust/lint that built up and it was a lot. It is a safety feature. It's a overheating protection feature that usually triggers if there is build up in the fan, front vent or vent pipe to the outside. I hope this helps.

need to bleed air out of filter at oil tank crack open the screw on top it will bleed out air wait until oil starts to run out then tighten back and bleed at heater on right side lever inside hole push and let off slow 4-5 times and restart