I have an Armstrong SX90 propane furnace. The ignighter gets gas and lights for a short time but the burners do not get gas to them. I have checked all the drain lines and they are free from obstructions. I cleaned the vacuum port to the burner box. I replaced the ignighter. Any Ideas?

Try cleaning the flame sensor with steel wool or sand paper. Be careful not to touch the black/grey area of the ignitor while cleaning the sensor.

The flame sensor and the ignitor were one unit and had been replaced.

How long ago was the flame sensor/ignitor replaced?

If these were one unit you probably have a Honeywell Smart valve? Correct?

If that is the case try moving the wires around where they go into the valve. These valves have had a problem with loose terminals causing the same problem you are having.

The sensor was just replaced and yes it is a honeywell valve which has an on/off switch to it. The unit was mfg around 1997. I'll try jiggling the wires etc. If that does not help is there a cetain voltage I should see at the valve?

See this other post I just did for another person. Down the page you will see much info on the Honeywell setup.

https://www.askmehelpdesk.com/heating-air-conditioning/ducane-furnace-wont-lite-402924.html

Thanks. I'll check it out.

Thanks for the schematic. It was not the smart (dumb) valve. By observing I gained wisdom that the flame from the pilot tube was not sufficient. I took it out and cleaned the orifice and that took care of it.

You were a big help.

Good deal glad you got it going.

Hello, I have an armstrong ultra psx90 propane furnace and my (what I call the cleanout fan, not sure if that is what it is called or not) runs and I hear the ignitor trying to ignite the fuel but it never ignites and the blower motor never turns on but the cleanout fan continues to run for a long time. I have a honeywell vr8204h 1097 gas valve and I think this might be the problem based on what I have researched. Does this sound like a reasonible assumption? If so, I'm trying to locate a valve that will replace the one I have, any help would be appreciated.

Thanks