Riello M3 (1985) oil burner won't fire or stay lit.

wolffie

System will be replaced was natural gas within a month or two, so I skimped on maintenance and quit buying oil. It was more reliable than usual until I ran the oil tank too low (down to 2"). Added 5 gal (1") diesel fuel, this did work, but it started reluctantly -- I know I'm s'pozed to use the RESET button sparingly, but I hit it 6-8 times before it finally lit and stayed lit. The added fuel may have stirred up sludge at tank bottom. Later, added another 5 gal diesel, then it would fire briefly and cut cut out, or not fire at all.
I've hit the RESET button way more trhan I'll admit, but haven't turned into a pumpkin yet. Will get a mirror to check for oil in the combustion chamber, which is very old and way too big, making CO too high, one reason it has to go (I have a CO alarm).
Replaced fuel filter (screw-on diesel engine fuel filter, it was over 1/2 water and sludge). Cleaned pump screen (didn't look too dirty but it does have a 1/16" hole in the screen!!).
Bled fuel at the pump, seemed clean but still foamy, tiny bubbles; the only way I know to get the pump to run for bleeding the air is to hit RESET. This is a 2-line system without a tiger loop and about a 15' trenched run to a buried outdoor tank (I've read that a 2-line system will prime itself).
Combustion chamber door is sooty but I don't think the cad cell is sooted over -- I pulled the control out, put a flashlight in the combustion chamber and could see its light through the cad cell's hole.
Pulled out the jet just 'cause a YouTube video showed me how. The turbulator was pretty clean.
Further air bleeding -- those foamy little bubbles -- is all I can think of, and I don't know how to make the pump run other than hitting RESET. This model has no zirc-like bleeding nipple, only a nut. The oil that comes out is still foamy.
This unit has a history of not shutting the blower off, so it blows cold air sometimes, requiring manual shutoff, and it does that now.
Last try, it did light but locked out after about a minute.

Unwilling to spend more money unless for bacon to fuel the corgi, my backup heating system. Probably corgi fur clogging the jet, it's EVERYWHERE. (:

1. How can I make the pump run long enough to fully bleed this line?
2. What are the consequences of abusing the dreaded RESET button?
3. Would it help to get naked, paint myself blue with woad, and dance counterclockwise inside a circle drawn on the floor with fuel oil while chanting to Vulcan?

STEVEusaPA

Assuming you replaced the fuel filter correctly and didn't introduce a vacuum leak, you appear to have a few problems.
If you have water in your fuel system it's never going to work.
To answer your questions:
1. I really don't want to tell you because it may not be your only problem & you may make it worse.
2. For a Riello, you will eventually damage the control, which will cost you way more than you are bargaining for.
3. No
If you're changing to gas in a few months, get a bottle of fuel treatment, dump it into tank at time of delivery. Order enough oil to get you thru until replacement. Have a qualified tech check everything you touched, and properly bleed the system.
Forget the 5 gal at a time nonsense.

BornForDying

Had a guy in my area who tried to fix his own furnace and ended up starting a fire in his house when he cycled the burner.

He should have called a professional. You probably should too.

lchmb

I'm a bit more concerned with your "making co to high" comment. I understand you want to save money, we all do. But you seem to have some serious safety issue's with what your dealing with...call a pro please!!

mrheat8

I sold a lot of mec and mectron burners, you should be able to use a droplight to fool the eye into thinking there is a fire at the right time. the control will not be hurt. I also used a 20 or 30 gal container as a fuel container. dont bother with a contaminated tank.

STEVEusaPA

I don't think it's very responsible to tell someone with no experience (and anyone else who comes across this thread) a method to fool a safety device.
The one great thing about a Riello is that it's nearly impossible to flood them.
This is why in my first post I mention it may not be the only problem here.

BornForDying

Is there a reason we need long bleed times? The burner has a tigerloop on it. If its firing properly (which is probably questionable), couldn't he just observe the tigerloop and watch for excessive bubbles?

No need to mess with lights in the tube.