Monitor 41 test fuel pump?

[EDNY]

My Monitor 41 worked great all Winter and now has stopped working. When turned on the air fan comes on, then after a "long" wait the orange scale lights up..runs for a while...then shuts down and the zeros start blinking.

The unit is clean and I suspect that the fuel & pump area "might" be of concern. I took off the copper line at the fuel pump (fuel is clean/full) and restarted the heater...no fuel pumps out during the entire cycle. I noticed that if I removed the blues wires on the pump and plugged them back in while running..I get a small squirt of fuel. The reading across the fuel pump is 616 ohms without connectors.

What is the voltage for the fuel pump?

BTW: Duriung the last cycle the 250v 2amp fuse (Fuse 1) popped. The ignitor cycle apears to be working, laid my Fluke wireless test light next to the unpowered line and at one point it powered up before the unit shut down.

Thanks

[hawkins111]

M41 fuel pump

The voltage for the pump is 105 DC at the K connector. The igniter should show 16.8 OHMs at room temp. Normally I would say you have an air safety switch not closing (blocked air or exhaust) or the rubber hose is off the switch. The fuel pump is not on unless the status lights are on steady. The 2 amp fuse popping is a big problem unless you touched something and did not realize it. If this continues you have a main circuit board issue.
Tom

[EDNY]

hawkins111

Thanks for the specs...I'll check it out tomorrow.

Ed

[HayZee518]

M41

Ed you're in Champlain I see, I'm west and south of you in Saint Regis Falls
I had an M41 when I moved here in 2000.
I never had a monitor nor even heard of one in my lifetime. I inquired about servicing it and was told it would cost around $350 just to look at it.
So, I started to see what makes it tick and started this forum to repair the heaters.
The M41 uses the taisan fuel controller which is now obsolete. I have since gotten an M2400 that has the fuel pump controller integral with the motherboard.
The fuel pump itself looks just like the one on the M41. Mulharney's is the local supplier. Down the road from you at Keeseville, Adirondack Hardware has parts for the Monitor.
When's the last time you cleaned out the fuel sump? Reason I say this is that water will accumilate in the sump and will rot out the metal linkage of the constant level control within the sump.
Water, mixing with kero forms a slimy brown gunk that needs to be cleaned out.
In your heater part of the constant level control is a black plastic float with a very small set screw at the end of the tang. DO NOT MOVE this screw. If you do you'll have problems.
The screw controls the height the needle valve travels. I found this out the hard way.

[EDNY]

HayZee518

You guys helped me get it up and running last a Fall, installed a new wick and welded the fuel nozzle back on the burner body back then. It worked great all Winter..(BTW: it's snowing like heck today!)

The fuel tank is spotless, no water or sediment. Been using an automobile clear fuel filter and watch for water etc.

Use the heater in my shop and might just get rid of it and look for another used heater. I see used units for sale and will stay awy from another M41.....maybe the M2400?

I'll remove the heater today and inspect the exhaust..it acted up after those high winds we had the other day. Normally shut it off when not in the shop..so maybe some critter moved in:-)

It did give me hints in the last couple of weeks though, while TIG welding near it, it shut down and began blinking..I just figured the TIG frequency affected it. The TIG welder does lock up my computer if I weld near it.

Ed

[EDNY]

Checked the intake and exhaust and blew out the air safety line. The switch appears to be working with slight vacuum.

Went and fired it up and Number 1 fuse blew again....just realized I have the manual so I'll look at the schematic tonight.

BUT NOW PROBLEM TWO!

Just replaced the 41 with a borrowed 441, my buddy claims it worked 3 years ago.

Installed it, removed the fuel screen from the tank, let fuel run through, reinstalled the screen, opened the bleeder screw. The hit the prime button a few times. Tried the prime and start procedure a couple of times now - same thing.

Turned it on, fan runs, orange scale goes up about half way, runs like that for a while, then clicks off and the orange scale blinks and fan shuts down. No heat at all...any ideas for this unit?

Thanks

[hawkins111]

M41

The M41 heater that continues to pop the fuse needs a new or overhauled main circuit board. You do need to read the manual to understand the fuel sump. The Red button on the sump is not a Prime Button. One time for one second is the rule of thumb. When you push the button down you are holding the fuel valve open and allowing fuel to fill the sump all the way to the top. I think you need more fuel in your tank. Not enough pressure to get through the line, valves and filter.

Tom

[EDNY]

RE: The 441

Turn it on, the fuel triggers (pump pulsates) but the ignitor never powers up...(has 15 ohm resistance). Can I jump the air safety switch just to narrow the problem down? Is the air safety switch normally open or closed?

Thanks
Ed

[hawkins111]

Air safety switch

If the pump thumps, its working and the air safety switch is working correctly. If the pump is thumping loudly, you don't have fuel to it.

Since you have checked the resistance of the igniter, I would check the board to be sure it's putting out voltage (120 volts AC for igniter). The board should show voltage to the igniter very shortly after initial start of the cycle.

Tom

[EDNY]

If the pump thumps, its working and the air safety switch is working correctly. If the pump is thumping loudly, you don't have fuel to it.

Since you have checked the resistance of the igniter, I would check the board to be sure it's putting out voltage (120 volts AC for igniter). The board should show voltage to the igniter very shortly after initial start of the cycle.

Tom

Tom

I have been using a non contact Fluke test light. I lay it near the fuel pump - it lights up when the pump receivers power. Do the same thing with the igniter, one side is always hot and the other powers on during the cycle.

How can I manually test the air safety switch?

Ed

[hawkins111]

M441 fuel pump

If the pump is thumping, it is working. The air safety switch is also working if the pump is thumping. If your tester shows the igniter is getting power then you have a fuel issue. You either don't have enough fuel pressure to push through the filter or the nozzle is blocked inside the pot. Be careful removing the fuel fitting on the burner pot. Don't try it if it's hot. With the fuel line off try to start the heater. If the pump is thumping and you do not have fuel, you have a dirty filter or not enough fuel pressure. If you have fuel and the igniter is hot, you have a blocked fuel nozzle.

Tom

[EDNY]

If the pump is thumping, it is working. The air safety switch is also working if the pump is thumping. If your tester shows the igniter is getting power then you have a fuel issue. You either don't have enough fuel pressure to push through the filter or the nozzle is blocked inside the pot. Be careful removing the fuel fitting on the burner pot. Don't try it if it's hot. With the fuel line off try to start the heater. If the pump is thumping and you do not have fuel, you have a dirty filter or not enough fuel pressure. If you have fuel and the igniter is hot, you have a blocked fuel nozzle.

Tom

Thanks Tom...that all make sense now. I'm aware of the line at the burner pot, that was one of the problems I had with the 41 last year, had to weld it back on.

Took a look at the schematic the #1 (2AMP) fuse that keeps blowing is in line with the transformer. I'll remove the transformer and test it tomorrow.

Ed

[EDNY]

Opened it up today, the pump solenoid board (part TS-A-62) is bad on the M41, will see if I can locate one locally. May be a couple of parts units out there.

Ed

[EDNY]

RE: The 41

I found another M41 and replaced the pump, pump solenoid and transformer. Turn it on, the fan runs for a few minutes then sounds like a relay activates and the Number 1 fuse (2 amp) still pops.

Can someone tell me the start-up sequence for the M41 so I can try to determine at what point it trips?

Thanks

[hawkins111]

Cycle timing

There is a post already on here that will cover that. Titled:Monitor 441 Heater dated 1/21/2008 post #98. There is very little you can do witht the main board. You are better off sending it out to Mathis Electronics in NC. They will fix it for a decent price. You have to really think about how much money you want to spend on a M41. Without overhauling the combustion chamber and blower motor, you have a half done unit that still may not work. If you do have the main board fixed I would not hook it up to the same circuit as your welder. Tom