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Troubleshooting Toyostove Laser 73

For the past week the overnight temperatures at the foot of the Mission Mountains have dropped to -6 degF. Coincidentally, our 275 gallon fuel tank ran dry, which caused our trusty little Toyostove Laser 73 heater (40,000 BTU) to stop working and start throwing error codes ("EE2" and "EE6"). These two codes generally point to fuel problems. Here's what I did to troubleshoot the problem.

The Toyotumi Laser 73 is a simple, reliable stove.

Things I did to troubleshoot my fuel-related problem.

1.) Define Error Codes

EE2 Error Code = Heater does not ignite.

EE6 Error Code = Heater does run through its pre-start sequence, ignites for a short time, then goes out. Likely obstruction (or constriction) in fuel supply or air supply.

2.) Helpful Info Online

YouTube Video: Toyotumi Product Overview, Troubleshooting, Maintenance

YouTube Video: Ohming the Ignitor on Your Toyostove

YouTube Video: Toyostove Error Code EE6

YouTube Video: Servicing the Flame Detector on Your Toyostove

Toyostove Laser 73 Manual

3.) Replace Filter at Tank

Before doing anything, I unplugged the stove and closed the valve at the fuel tank. The stove uses #1 heating oil, which is crystal clear kerosene or ultra low sulfur diesel, dyed pink for "off road only" use. Fuel leaves the tank, runs through the filter, through a 3/8" copper tube through the wall into the house. The filter unit is a ZeeLine/National-Spencer Model #NS-10 Filter with 1" NPT threads ($50.00). It is a water-separating design that comes with a replaceable canister filter ("No. 20 Element", $10.00). The previous homeowners had not serviced the filter in years (decades?), so the plastic housing was nearly opaque, baked orange by the sun, and brittle. The plastic crumbled in my hands with the first twist. Our local Cenex had a replacement unit on the shelf.

Old filter: National-Spencer

Old filter, broken upon removal.

New filter unit: ZeeLine/National-Spencer Model #NS-10

4.) Test Resistance on Ignitor (Ohms)

Remove front cover of stove (remove 2 screws from L and R sides). Remove control panel (4 screws). Follow red wires from ignitor to location on main circuit board marked "G". Unplug the white clip from board. Set multi-meter to the upside down horseshoe (ohms) and slip probes down back side of clip, following the wires in, to read 16 to 17 ohms (normal range). Mine was working fine. See video listed above.

Proper range is between 16-18 ohms.

5.) Kinked Fuel Line

I noticed some new, very gentle rhythmic thumping at the fuel pump during the ignition process, so I closely inspected the entire fuel line. At some point in the past, the 3/8" copper tubing got kinked at the tank end. Right at the fitting, actually, which made it hard to see. I cut out the offending flare-type fitting and replaced it with a compression-type fitting. Use a small wheel-type tubing cutter, some emery cloth, and a crescent wrench.

The kinked section of tubing I cut out.

Compression-type replacement parts are easier as they do not require a flaring tool.

6.) Inspect Fuel Strainer in Stove

Get a phillips screwdriver, needle nose pliers, and some paper towels. Remove three screws, pull out filter, inspect, and clean. The video listed above ("Toyostove Error Code EE6") shows you how to do it. 10 minutes or less. The amount of fuel that will spill out is less than 1 oz. My filter was clean.

The fuel screen is located on the right side of stove, below the opening for the red reset button. Loosen those three screws and remove the little plate and its rubber gasket. Make sure to catch the small amount fuel that will leak out.

I didn't know just how much fuel would leak out. Turned out, it was about 1 oz. I went a bit overboard with the paper towels. Sorry, not sorry.

Pull the little fuel screen out with needle nose pliers to inspect. Metal clip goes toward the front of stove.

7.) Clean Flame Sensor

Its a simple matter to unscrew, twist, and remove the flame sensor unit. Its located right above the ignitor on our stove. Clean up end with some emery cloth and reinstall.

8.) Set Clock So Automated Cleaning Cycle Works

The clock must be set in order for the self-cleaning cycle to run. Cleaning is programmed to run at 2am. You can set the time to anything you want, but it must be set to something. During the cleaning cycle the display will show "CL10" code.

9.) Fill Tank with Fuel

The fuel delivery truck isn't scheduled to come our way for a few days, so I drove into town, filled a few tanks up at Cenex, and poured them into my nearly empty tank at home. While the Laser 73 has an internal fuel pump, its not a strong one like car engines have. Its basically a gravity-feed system, so the bottom of the fuel tank must be raised more than a foot higher than the elevation of the fuel inlet fitting entering the back of the stove.

Racing-style gas tanks are the only way to go these days. None of those annoying safety nozzles.

10.) Observe Flame Color

With the stove running, the flames can be observed through the front louvers. They look a bit too yellow on my stove, which means the unit and flue may need to be cleaned. They should be blue. I'm not going to do that cleaning now. See manual if you are.

11.) Test Stove to Confirm Fix

Plug in stove, open fuel valve, and press go. Stove works fine now. The problem was a combination of low temps (sluggish fuel), kinked line, and low fuel level.


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