My mr Heater MHU75 it was runnig fine but now the draft motor starts and after a while the igneter comes on and the flame turns on but as soon the igneter shut off the flame shut off too it does 3 times and then locks out and goes on 2 blinks if I cut the power and turn on again does the some things again sometimes the flame stay on for a minute or so and then cuts off thanks

Mr heater mhu75 light flash 4 times

could be control board

Yellow flame means a 'not perfect' mix of gas and air. As long as it goes blue, then it's fine.

Propane heater with yellow flames and roars ' Hearth.com ...

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Jan 24, 2013 - We installed a comfort glow 50k vented propane heater for my mom. ... I went up yesterday and there was a fair bit of yellow/orange flames. ... burner & any misalignment will allow the gas to shoot out the side of the air shutter, ...

Is my new propane heater working right? - Canadian ...

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Not a heater for a non vented place. As for the flame being yellow, that comes from the air to gas mixture, not enough air and the flame will be ...

VIDEOS as well

https://www.google.com/search?q=MR+HEATER+SHOOT+A+YELLOW+FLAME

..

Yellow flame indicates insufficient air is being injected into the mixing chamber - air hole blocked or restricted maybe.

Yellow flames indicate a general lack of oxygen and also a yellow flame is dangerous as it is producing high levels of carbon monoxide.

There are too many reasons for this to happen so we would have to narrow it down. The sequence of operation on a Goodman furnace is usually:
1: Inducer draft motor comes on
2: Hot surface ignitor comes on and glows
3: Gas valve opens, lights burners
4: Flame sensor detects flames
5: Blower comes on

If the inducer motor never came on, then you start looking at power to the unit, thermostat issues, or inducer motor issues. Just a few places to start. Hope this helps!

Your pilot flame should be blue with a small yellow tip, and it should cover the thermocouple (a small rod in front of the pilot light). If the flame is too small and doesn't cover the thermocouple, it may be adjusted too low, or you have low gas pressure or you have a leak in your gas line coming in to the heater. If the flame looks like a lazy yellow flame, you are probably not getting enough air to the flame. Check that your air openings around the pilot are not clogged up. If the flame looks like a waving blue flame then you probably have excessive draft at the pilot. If the pilot flame looks good and covers the thermocouple, then the thermocouple might be bad. Best of luck. I hope I have helped.

Problem: Your furnace will not ignite the gas to produce heat for your home. When a furnace has a bad ignitor what I see most of the time is the following sequence of operation:

1. Thermostat calls for heat. 2. Draft inducer motor starts. 3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes. 4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back off and on again. Then the sequence starts all over again with no ignition of the gas. Solution:You probably need to purchase and install a new ignitor. I would suggest that you inspect your ignitor closely for cracks. Make sure you do not touch the ignitor with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, rollout switch problem. The furnace's control board might not be supplying the voltage to the ignitor.If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then you need to clean your flame sensor with light sand paper or steel wool. You might need a new flame sensor, but most of the time they can be cleaned an will work well after cleaning.

Seems like the valve is not opening up fully or the adjustment is out of adjustment. Try adjusting the flame.

sounds like the filter inside of the unit may be dirty and or the vent cap could be partially blocked causing the flue gas to build upo until the unit tripos on the high limit saftey

How about the thermocouplin have you tested that?

If the MH75KT is the correct model, then it is a Kerosene only heater. Fuels, like oil and diesel all have different ignition points.
http://www.mrheater.com/upload/newsletter/70276_MH_HS_50_75_125_175_210KT_REV%20A.pdf
See page 3 of the manual.