Waste Oil Heater Forum - Your definitive source for burning waste oil for heat.

Thank you for sending the video. It appears your on-board air compressor is shutting down. Lets start with cheap/easy things to check first. Clean air filter ? Double check all your wiring connections to make sure we do not have a loose connection somewhere. Especially in the on-board air wiring box where there are a few wire nuts and capacitor. Is the compressor still getting power when it shuts down ?

Im quite sure all is well with plumbing as it worked perfectly for 5 winters.   The temp is at 140,  but ive raised it up and no changes.   i always kill the power to unit if its not being used, as i was told this keeps the block from plugging up.  Doesnt  quite add up how pressure at the gun varies so much.   seem like the longer the unit is off, the higher the pressure on start up.  once it settles to  about 2psi all is well.   I guess a rebuild and re clean all passages again is a good starting point
P.S.   one thing i did notice today.  units been running pretty much non stop, oil pressure holding steady at 2.  If i quickly raise air pressure to 20 psi   the oil pressure rises to 2.5 ,   if i lower the air to 10psi the oil drops a little too.  is there a connection between the two?

I just noticed your PS. Oil pressure should not change when adjusting the air. Bad o-ring on the nozzle ? Has the nozzle ever been changed ? Also make sure the nozzle t-stat is functioning properly. I have had them fail closed then the nozzle heating element stays on constantly baking the nozzle o-ring.

When I do a burner rebuild I totally tear it down and scrub out each passage until spotless. Regulator and solenoid bodies cleaned spotless. Nozzle holder scrubbed out. On some preheat blocks I have had to clean up passages with a drill bit. The oil solenoid has some small passages on both the body and block that need to be checked closely. Every burner rebuild gets a service kit installed.

Sounds like things are good from pump to tank so that leaves the burner. What is your preheat block temp set at ?

Ok just to be clear you have a CB-1750 with a J-pump ? We have a couple of things I would look at first. #1 would be a burner rebuild. I am very picky about this and do not like my customers attempting it since they usually get frustrated and quit early before getting the inside of the block and nozzle holder spotless. #2 pump to pickup screen. There is a screen inside the pump head that should be cleaned every 2 years or so. Replace the pump cover gasket and do not use any kind of sealant. When oil pressure is dropping down how much vacuum are you pulling at the Lenz filter ? I have seen only a couple of times a rag or a big glob of something slowly plug the pickup screen, vacuum goes up on long run times causing oil pressure to drop. When the heater would shut off the rag/glob would fall off the screen.

Ok..........this does not make any sense to me but lets see what we can figure out. The blower is turned on/off by the fan switch. What does the flame look like when this happens ? Is the oil gauge steady or does it bounce ?

Ash buildup would be your biggest killer of efficiency. 

The electrical part of the solenoid might be shot now. Leaving the plunger out is not a good idea. With no plunger oil will continue to drip out the nozzle when the burner shuts off. You can bench test the solenoid with just the stem and plunger. Power the solenoid on/off while on the bench to see if the plunger goes up/down.