Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › Long Term Fuel Trim related to vacuum leak › Reply To: Long Term Fuel Trim related to vacuum leak February 12, 2020 at 12:44 pm #897243 Richard KirshyParticipant If you believe your dealing with a vacuum leak. There are several methods to try to pin point the source. Water spray Propane Smoke test