I am helping a friend troubleshoot a Suburban LP furnace. When the furnace starts it take several ignitions cycles before it stays running. The furnace "lights" for a fraction of a second (a puff of warn air) then goes out, then "lights" again. It takes several of these cycles before it stays running. You can hear the gas solenoid click turning on the gas. As best we can determine once the gas is on it stays on. The Sail switch is also working since the gas and ignition is turning on. Is it normal for it to take several ignitions cycles for it to stay lit?

ILVMYGT wrote:...snip... Is it normal for it to take several ignitions cycles for it to stay lit?I would say no. My best guess is the computer is not sensing a flame and it takes a few attempts before things heat up enough where it does. If it was me, the first thing I would do is clean the high energy wire to the sparker on both ends.On Edit:While I had that wire off I would also take out my meter and check to make sure it has good continuity. Flex it a little while watching the meter. Very possible it might handle the high spark load, but loose a little too much in the flame sensing ability.

What is the model of your Suburban furnace/It could be dirty contacts on the circuit board connector.Furnace may need cleaned and the electrodes adjusted.

No, it should light on the first of the 3 attempts. From your description, the Spark electrode is probably NOT at the correct gap. Doug

The burner was removed, cleaned and blown out with compressed air. While the burner was out the inside of the "combustion chamber" was vacuumed out.The connector for the electrodes and gas solenoid at the control board was cleaned. While starting the little bulb on the control board flickers when the electrode sparks.The electrode was replaced with a new one with the correct gap. Before reinstalling the electrode the high voltage wire was connected to it and spark was verified.This is an older furnace (1993). A review of the schematic there does not appear to be a separate sensor that detects the flame. The burner jet has not yet been cleaned. But you can get slight gas smell when it first starts.

This manual may help.Suburban manual from Bryant RV

Furnace Ignition Question | Good Sam Community

dougrainer
Nomad
Nov 27, 2015
No, it should light on the first of the 3 attempts. From your description, the Spark electrode is probably NOT at the correct gap. Doug
enblethen
Nomad
Nov 27, 2015
What is the model of your Suburban furnace/
It could be dirty contacts on the circuit board connector.
Furnace may need cleaned and the electrodes adjusted.
John_Joey
Explorer
Nov 27, 2015
ILVMYGT wrote:
...snip... Is it normal for it to take several ignitions cycles for it to stay lit?

I would say no. My best guess is the computer is not sensing a flame and it takes a few attempts before things heat up enough where it does. If it was me, the first thing I would do is clean the high energy wire to the sparker on both ends.

On Edit:

While I had that wire off I would also take out my meter and check to make sure it has good continuity. Flex it a little while watching the meter. Very possible it might handle the high spark load, but loose a little too much in the flame sensing ability.

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