Installed replacement "used" ECM with battery disconnected. Installed jumper between DLC pin 4/13 & let the dash blink for 1hr, turned off key, removed key from ignition, removed 4/13 jumper, inserted key and tried starting. Cranks, starts, cuts out after 1 sec., tried 2 more times but same. B2799 code is active in ECM. Cleared code but it comes back right away.