My pump pressure will not adjust down...no matter how much I back out the screw....What could be my problem

The air pump sounds like its ok, probably an air leak somewhere. Does it have many hours on it? Could be the nozzle not atomizing the fuel enough at low pressure to get it to burn properly. Could be the rubber seal on the nozzle stem. Do you have fresh clean fuel in it? Is the photo eye in its proper holder and the lens is clean? These heaters can be fussy sometimes

These things are extremely sensitive to pressure adjustments. They usually cannot be set precisely without a manometer or very low resolution pressure guage.

Google reddy heater for a very detailed description of what the adjustments are and how to properly adjust them. It may cost you a few bucks for a proper guage, fittings and a few inches of tubing.

You need a pressure guage to connect to the port beside the one you used to adjust the mixture. The pressure you want is listed on the data label of the heater. A pressure guage with a range of 1-15psi is best.

Remove the top of the heater and turn it on. Look for the igniter to start sparking if it uses the spark plug type igniter or if it uses a HSI type, look for it to start glowing. Next, use a flashlight to look for fuel spraying out of the nozzle. If it isn't check the nozzle for a clog. Check the fuel filter. Remove the filter cover on the back of the motor and check the air filter. If this doesn't get the fuel going you will need to get a pressure guage to screw into the left hole in the filter cover and check the air pressure going to the fuel nozzle. It should ~3.5#. You can adjust it by turning the adjusting screw in the other hole in the filter cover. That plug should have a hole in it.

Have you checked the air pressure it should be around 6lbs. to do this is in the back on the filter cover remove plug that is on the left side insert a pressure guage turn on heater and look at guage you can adjust air pressure by turning the slotted screw that is to the right of the guage. If you cant get 6lbs of pressure then check the rotor assy. and check to see if you have any cracks any where on the filter cover.

the black hose that goes to the back hooks to a pump on back of motor take screws off back and filter clean when back together turn fan by hand and should hear a small vacum at back of motor , not pluged in clean nozzel

HAVE YOU CHECKED YOUR FILTER AT THE FUEL TANK?

The R50 does not have a thermostat.

The 2 knobs that you mention- are they the screws in the black plastic end cover?

If so, these are the heartbeat of the fuel system and do not adjust. They adjust the air pump pressure which puts fuel in the nozzle and atomizes it. The pump pressure is critical. If the pressure is not correct the heater will shut down.

If you have adjusted the screw with a hole in it you will need to reset the pump pressure to specs. It's easy. http://reddyparts.com/photocell_test_sp.htm

Now, if you have not adjusted the pump, then you might want to check the tank for water.
Troubleshooting tips

This sounds like a fuel pump check valve problem, if the fuel is not kept in the filter and lines by the check valve it drains back into the fuel tank and causes the kind of problems you are having, you can check this by hooking up a fuel pressure guage at the test port on the fuel manifold that supplies fuel to the injectors, run the engine and shut it down, note the fuel pressure at shut down (with the test guage hooked up), walk away for an hour, come back and check the pressure, it should not have dropped more than 5 PSI You can buy a universal fuel injection pressure tester for about $25.00, cheaper than having a shop run the test. If the pressure drops you found the problem, bad news is the check valve is in the pump, the pump is in the gas tank.

You don't state whether this heater has the old style spark plug technology or the newer Hot Surface Ignitor technology. Troubleshooting will be different, depending on the style of heater, because the electronics are different.

You ask "what are the two adjustments screw heads on the back of heater". As stated by tros1 these are A. an air pump adjustment screw, and B. a pressure relief valve.


Both technologies require correct pump pressure in order to deliver the fuel at the proper rate. For a pressure setting video
http://youtube.com/watch?v=NeM3Yi9Y1oE

Reply with the model number and/or the specific ignition technology and maybe we can help.