Monitor M41 issue

[kupple]

I have a Monitor MPI M41. I inherited with the house. It worked fine last fall, winter, and spring. I went to light it this fall and so far it will light and the burner flame is orange. It stay lit for a couple of minutes then goes out and the Burner status light blink. I was hoping it was just low on fuel so had the outside tank topped off. I changed the fuel filter on the tank. The fuel was delivered and I believe the valve on the tank was open to far as the fuel was all over the floor. I have since turn off the tank and cleaned up all the fuel under the heater and on the floor. is there something wrong with the heater that it would keep letting fuel through or was it because the valve on the tank was open to far. The heater is 2 and a half hours away from me so my father in law is helping with it. I have read the forum on this site and others because I found this site last. I do not have anyone in the area that seems to know anything about these heaters. My father-in-law and myself are mechanically inclined but are trying to keep repair cost down as much as possible. I will check when I get back up there the exhaust and intake are not block by any foreign material. The glass does seem to be fairly clean. I am not sure on the carbon buildup in areas. Can I see it through the glass or do I have to take apart. How much can I do without needing to replace gaskets or parts? I am hoping to go up Wednesday but will not have parts but I could do a cleaning and also check exhaust and intake. I appreciate any advice! PS I am a computer tech not a hvac tech but I can follow directions. Thanks

[HayZee518]

M41

The M41 is an old unit but one that I have the most experience with. I had one here before I upgraded to an M2400.
The only way you could have kero on the floor is if the constant level control malfunctioned. Unplug the heater
shut off the fuel flow from the tank. make a trough out of aluminum foil and place it below the plate with the two screws and into a pie plate. now remove the larger screw. this will drain the fuel out of the fuel sump. Next remove the plate, gasket, spring and filter. Check that the stainless filter is clean. If not, use gumout carb cleaner to clean it off and blow it dry with compressed air. While you have the filter out use a Q tip and clean out the chamber. There is a hole at the far end which is the inlet to the needle valve seat.
Remove two spade terminals from the fuel pump, the brass nut on top of the solenoid pump and pull the capillary out.
remove the two screws holding the top plate and remove the pump and plate as a unit.
Look inside the sump. Is there any brown gunky sh** inside?
If yes then the sump tank needs to be removed and cleaned out. Use a 9/16 inch wrench or a 15mm wrench and unscrew the gland nut in a clockwise direction. Remove the four screws holding in the sump tank and remove the tank.
NOW BE VERY CAREFUL!!
Unscrew two screws that hold the float in the tank and remove the float. Don't disturb the black screw on the tang.
Remove the needle valve and spray gumout inside. Inspect the needle valve tip. There should be a rubber neoprene arrow shaped thing. This is the needle valve.
Check to see if the metal linkage is still intact. There's a spring that activates the toggle over center lockout.
The other linkage is the reset for the lockout.
Once the sump is cleaned out, put everything back together and re-install the tank into the heater. Replace the filter, spring, gasket and plate with the two screws, replace the large philips screw with the o ring gasket. Connect up the fuel line. Have someone open the outside tank valve and watch where the fuel level goes to. if it looks like it will overflow the sump tank, shut off the fuel flow.
The needle valve projections have to be above the lockout linkage.
If everything looks ok, replace the solenoid pump and plate being careful not to have the pump body touching the float.
Replace the wires, plug in the unit and try to start the heater.
When the heater shifts into high fuel flow rate it'll try to empty sump tank but if your fuel flow is fast enough it'll keep the level steady and the heater should work.

[kupple]

more info

HayZee518: thanks for the quick reply. one other piece I failed to mention. Before I had the truck deliver more fuel, I took the plate, gasket, spring and filter out and cleaned the filter. it was not stainless steel. It was plastic and tubular with a screen all the way around. There was a little bit of brown pieces of gunk. I cleaned them off and put everything back. I am sure I put the rubber gasket back on when I replaced the plate. Is it possible that the fuel was leaking from the plate? I was also concerned that I had some sort of fuel blockage. I am also assuming that fuel is at least getting to the heater. My father in law opened up the valve on the tank and said that he did not see any leaks. he tried starting the M41 and still got the same result. fan starts burner lights then after a few minutes the flame goes out and the burner status lights blink and the clock resets to 88:88. He then turned the tank valve back off.

[HayZee518]

M41

The only indication you'll get as far as burner status is the eight flashing orange lights.
when there is no fuel in the sump, the pump will start to make a thump, thump sound and the burner shuts down and locks out.
my guess is because you found some brown stuff, that the sump tank is loaded with it. it'll have to be removed and cleaned out.
you are correct in observing the internal filter being plastic. It's been a while since I had the M41 so I forgot what it was made of.
the bottom of the solenoid pump also has a small filter.
the instructions for the heater say to press the red button on the side once. what this does is manually open the needle valve until the float acts on the fuel going into the sump.
it also resets the lockout linkage.
you might take a piece of rubber and fashion it into a gasket for the heater/plate and re-install it.
it's kind of a flimsy way of fitting the unit with a gasket - only being held there by two opposing screws.
a piece of an inner tube will work.
clean out the sump tank and get back to me.

[hawkins111]

fuel leak M41

You should be able to tell exactly where the fuel is coming from by just putting your finger on the area you think is a problem. If your finger is wet at all you have a problem. The areas to check are, filter cover, flare fitting at the back of the heater, top of the sump, and the fitting at the back of the constant level valve (sump). If you cleaned the filter on the stove and you have a leak, I would look there first. Opening the valve all the way has no ill effect on the fuel system. You have the same pressure in the system with the valve cracked or wide open. The pressure is a factor of how high the fuel level is above the bottom of the stove. Give us an idea how high the bottom of the tank is above the floor the stove sits on, and how big the tank is? Tom

[msearcher]

fuel leaking

I have seen a few heater that must have had water in the sump cause the bottom of the reset lever to rust off and prevent the float from
stopping the incoming fuel. In that case I have had to replace the sump.

hope that is not the issue.

[kupple]

couple more questions

Tom: -- I believe the tank is 12 - 16 inches above the floor. that is a guess as I am not up there. it has been that way for quite a few years. I am going to check the intake and exhaust while I am up there. I am assuming I take the hoses off of the back and check for any blockages. When I do take them off do I have to worry about O rings? I am also thinking about removing the line from the solenoid pump to the combustion chamber and using the wire to check the combustion chamber side for any carbon blockage. I am trying to start out without removing any gaskets because to start with I will not have any gasket parts this round. I could maybe find bearings for the fan if they seem to be the issue as again the flame seems to be orange not blue. I will look in the window when the burner lights and see if can see any carbon bridges down and to the right. I am attaching a picture of the side the stainless steel lever is that the same as the red button you guys are talking about? Also a picture with the grill off. Again guys thank you! thank you! for all your help and advice

[hawkins111]

M41 fuel leak

My directions were to help you find a fuel leak. Do not take the lines apart until you figure out where the leak is. No, there are no "O" rings in the fuel line system. Just touch your finger on parts of the fuel line and sump and figure out where the leak is. Looking at your pictures I can tell you have no leak at the top of the sump or the line going into the sump. That leaves the filter chamber cover or the line going into the back of the heater. The rest of a complete overhaul should be covered in another post. Tom

[kupple]

I appreciated the advice on the leak. I will use all of your advise once I get back to the house. It is 2 and a half hours away. I was just trying to have a plan and be ready to work on the heater once the leak is stopped and verified. The O rings I was talking about was on the intake and exhaust hoses. I want to verify the airflow coming in and going out that there is no blockage.