05-27-2026, 06:09 AM
If the engine accelerates to rated speed and slows down, there are a couple of things you need to know, is the fuel solenoid pulled in? (Visual or voltage check), does the engine exhibit black smoke? (Indicates high load).
Typically, the controls don’t allow the engine ignition system (the 12v that keeps the solenoid in, the gauges alive, and lift pump running) to stay alive without ac voltage. So that might be the case here, no ac volts and the ignition system goes down but the solenoid linkage is binding keeping the engine running at low speed.
No mention of hours but Kohler brush style ends usually run 7000 hours or more before needing brushes. If you can get to the brush holders, look at brush length. If it’s good or decent, the regulator might be faulty.
Of course the fuel system could also be the reason the engine speed drops. Lots to check but I think you have two issues here.
Typically, the controls don’t allow the engine ignition system (the 12v that keeps the solenoid in, the gauges alive, and lift pump running) to stay alive without ac voltage. So that might be the case here, no ac volts and the ignition system goes down but the solenoid linkage is binding keeping the engine running at low speed.
No mention of hours but Kohler brush style ends usually run 7000 hours or more before needing brushes. If you can get to the brush holders, look at brush length. If it’s good or decent, the regulator might be faulty.
Of course the fuel system could also be the reason the engine speed drops. Lots to check but I think you have two issues here.
Gordon Jones
1989-42~no slide-#188
2000-45'-2slide-#567
1999-45’-no slide Prevost XLV Marathon