Spark Pilot goes out in 2 secs so no time for Burners to ignite
I too don't like the dancing pilot flame but I don't see how a cracked heat exchanger can affect a normal pilot flame before the main blower comes on.
First test to try.
It sounds like you are losing the power to the pilot solinoid if the pilot is shutting down in two seconds. I would be measuring between the gas valve's P & C to first see if that current is also dropping out when the pilot drops out. If it is still being powered when the pilot flame drops out then the gas valve is in question.
(one exception can be some very light debris inside the pilot tube that is forced by gas pressure up against the pilot orifice. Once the pilot shut down occurs and the gas turns off, the debris falls back down until the next call for gas) Two seconds of pilot flame is just about right for that!
The second exception would be if you have very low gas flow (as opposed to pressure) from a gas cock that is almost shut off?
If the power to the pilot solinoid is dropping out within a couple of seconds then the ignition board is in question, as Harley points out..
Last edited by how; 01-25-2012 at 11:12 PM.