Cummins/Onan — Cold-Weather Starting Using the Preheater
Operation · Preheater / glow plug system
From a Cummins/Onan owner's manual covering: KT38, KTA19, Kt19, KtA38, KtA50, N-855, NH-672, NH-743, NH-855, NT-855, NTA-855, NTC-270…. Check it applies to your exact model before use.
Applies to: Cummins/Onan Kt19, Cummins/Onan KTA38, Cummins/Onan KTA50
Before you start
- Do not use vapor in conjunction with the preheater; to do so could result in a fire.
- Use of the primer before the 20-second interval will wet the glow plug and prevent heating.
Procedure
- Set the throttle in idle position; turn the glow plug toggle switch to 'ON'; the red indicator light must be on.
- After the red light has been on for 20 seconds, start cranking the engine.
- Operate the preheater priming pump to maintain 80 to 100 psi [552 to 693 kPa] fuel pressure.
- If the engine does not start within 30 seconds, stop cranking; wait one or two minutes and repeat.
- After the engine starts, pump the primer slowly to keep the engine idling smoothly; in cold weather this may require 4 to 5 minutes.
- When the engine has warmed up, stop pumping, close and lock the primer, and turn off the glow plug toggle switch.
- If no start during the first three full strokes, touch-check the intake manifold for heat and check the electrical wiring.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Glow plug should be white hot; amperage 30 to 32 (minimum)
- Preheater approved for starting aid capabilities to -25 F [-32 C]
Full service-parts list: Cummins/Onan Kt19 →, Cummins/Onan KTA38 →, Cummins/Onan KTA50 →
Source: Cummins/Onan owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.