Monitor MPI 41

[james28909]

hi, i have a Monitor MPI 41. was working great, but now its messing up.
let me describe to you the details.

i unplug the heater. let it sit for a few secs. then i plug it back in and press the thing on the side 3 times and release very slowly (i only do this once in every 10 attempts to get it going). the heater fires up, can see blue flame thru the window. then the fan will kick on as if its going to work great. but after a few mins you can hear some sort of knocking for about 10-15 secs then the flame gets very bright yellow and then the heater shuts off.

i have to unplug and repeat to stay warm. its 16 degrees outside and i need this thing working ;D


i should add this thing runs on dyed kerosene from the store which i am sure is #1

[hawkins111]

M41

Clean your fuel filter on the stove. Change the fuel filter on your tank. While around the tank make sure you have fuel in the tank. Six inches of fuel is not enough pressure to force the fuel through the filters and lines. If you don't understand the "little button" on the sump don't push it. The rule of thumb is one time for one second. Otherwise you can flood the heater BAD.

Try the above and get back to us.


Tom

[HayZee518]

M41

that red button on the side of the heater resets the mechanical lockout and holds the needle valve away from its seat. that is why hawkins said to press it once and let go. repeated pushings does nothing. it doesn't prime anything. it does open the needle valve. you could over fill the sump tank. inside the M41 sump is a black plastic float that is connected to the needle valve. there are projections on the needle valve that touch the lockout lever. when you press the red button you are manually opening the needle valve.
that thumping sound you hear is the solenoid pump starving for fuel. after a delay period, the burn lights flash and the system locks out.

[james28909]

well i did check the filter at the tank, flow is good from filter to stove.
and yes after the pump stops the burner lights do flash, then it shuts down.lockout.

so i must check the filter on the heater...
where is it located? because i think its the filter on the stove. it will burn fine and push heat until the pump kicks in, then i can hear the knocking sounds from, im guessing the pump, then it shuts down/locks out. been doing this all night just to keep it above 60 degrees.

so i think i will detach the fuel line from the heater and drain what is in the heaters resevoir. then check the filter in the heater itself.

thanks

[james28909]

cleaned a filter in the reservoir that was behind a metal plate with 2 screws. was dirty as hell, i couldnt blow thru it :0
i cleaned it real good and let it dry beside this other smaller heater.

if i had a better idea of how the fuel comes thru the reservoir then i think i would have a better chance of figuring this out. cause i get real good flow all the way up to the heater. and pump does pump for 1-2 mins then it starts knocking/running dry. still doing it even after i cleaned the filter, and actually, after cleaning the filter it seems to be doing slightly worse -.-

[HayZee518]

M41

you are correct in cleaning out that stainless steel filter. next time use gumout carb cleaner. it dissolves most anything but won't attack the plastic used in the heater filter. you don't need to disconnect the whole heater to service this, just stop the flow to the heater,
make a trough out of a few layers of aluminum foil and feed this into a shallow pie pan. now open [unscrew] the large phillips screw. there's a O ring on this. it will bleed fuel out of the sump.
another guy had asked how to remove the sump for a more thorough cleaning. look through the previous posts and you should find it. I jotted this down only yesterday.
the solenoid pump has a stainless screen on it too, at the very bottom. unplug the unit. shut off the fuel. remove the two spade terminal wires, unscrew the small brass gland nut and pull the cappillary out. remove two screws on the solenoid body and the pump lifts out.
if you want to remove the whole tank, unscrew in a clockwise rotation the fuel inlet line with a 13mm open end or small adjustable wrench, remove four phillips screws in the base and the sump lifts out. remove two opposite corner screws and the top plate comes off. look inside for any brown gelled crap. this is kero mixed with water. clean this junk out. use gumout and q tips. blow out the sump.
the fuel path is such: through the inlet, through the sump filter, up through a small hole at the rear of the filter chamber to the needle valve, then on into the sump where it acts upon the float. when the level reaches approx the 3/4" mark inside the tank, the float shuts off the fuel. there's a small depression in the tank where the sol pump goes. put everything back in reverse order and open your tank valve. allow a few minutes for the fuel to flow to the heater. now press that red button once or twice and let go. the sump should fill and stop. when the heater starts you'll hear some thunks until the pump primes and starts to feed fuel to the combustion pot at which time a flame should start if all the inline safeties are closed.

[james28909]

guys, i would like to thank you for all your help.

seems i finally did fix it. even tho the filter outside seemed to be getting good flow thru it, it indeed was NOT getting "proper" flow. i temporarily bypassed the filter on my tank, and tried the heater without it and viola. so tomorrow i will be going and getting a new filter. i had a feeling that was the problem to begin with but listened to someone else.... i see where that got us. well now atleast the kids can get ready for school without having to freeze to death.

hopefully this thread will help another freezing family.

thanks for taking the time and helping people like me out

[HayZee518]

fuel tank

I took out my tank filter completely. It's been off the tank for the past 8 years with no problem. the felt inside gets coated with water and then the problems start.
it also reduces the gravity flow pressure.

[james28909]

I took out my tank filter completely. It's been off the tank for the past 8 years with no problem. the felt inside gets coated with water and then the problems start.
it also reduces the gravity flow pressure.

this is exactly what happened to me i believe, and the heater is still going strong. so if anyone else reads this thread with same symptoms, check filters first especially if the heater was working fine before.

[dd20399]

mpi 41 window glass thickness

was wanting to order a window glass for mcmaster carr,borosilicate ,i want to have one before i take the old one out,i need to know the thickness or part # if someone has this info ,i would like to order one