Water heater trouble shooting

[Budget Appliance Repair]

It doesn't say so for your model but on the newer ones, (the second manual), they talk about a 3 second delay before the flame sensor is checking for good steady flame after main burner lights - this appears to be when your flame falls down and most likely not able to get a stable/clean millivolt reading for the ignition module to say flame is steady so it shuts down and retries.

The flame sensor comes into play at two points of ignition, the first time is to see that pilot has ignited and is steady and to turn off spark - that is all working correctly or the sparking wouldn't stop and the main burner wouldn't light up.  After the main burner lights there is then, (I suspect), the 3 second delay to make sure the flame is burning correctly then the sensor kicks on to make sure and if not shuts down and retries ignition sequence.

 

[JJ 109]

Thanks to all suggestions guys. I got the power vent fan (had to order it) and installed it last night and it works now. Even though I had the pressure switch bypassed, it appears that without air current in the burner the flame would pull away from the flame sensor and shut it down. 

Sent me for a loop, because I thought I had it fooled into thinking the fan was there. Cost me replacing the valve too and a lot of grief.

[John5five]

did you ever figure it out. seemed the murcury bulb broke closing off your primary air to the burner