Beckett AFG still fires after shutoff

[moto823]

Hows it going fellas? Quick question for you.

Just went to service a Beckett AFG burner for the season. This is the fourth year I have serviced this unit, and I am fairly certain this was never a previous issue

When the burner de-energizes and winds down it still fires for a few seconds. There is no oil delay solenoid. It was my understanding there is a check valve in the pump to prevent flame on shutdown? Explain please?

I cleaned out the J-tube and the check valve in the nozzle adapter was free and clean.

Any info is appreciated.
Thanks

[R Mannino]

Sounds like the cut off in the fuel pump is bad. Put fuel pressure gauge on the nozzle line, when the unit locks out the fuel pressure should only drop by about 15% of the running pressure.

http://www.suntecpumps.fr/Suntecus/Technical%20Literature.htm