1985/10/21 Caterpillar

Engine Shuts Down Immediately After Start-Up {7400}

Usage:

3208 And 3300, 3400, 3500 Series Marine, Industrial, And Generator Set Engines Equipped With New Wiring System Or That Are Packaged Generator Sets

Reference: Service Magazine, February 13, 1984, Page 5, "Engine Will Not Restart Immediately After It Has Been Shut Down".

There are four basic causes for an engine shutting down immediately after start-up. Use the chart, solutions, and illustrations in this article to aid in troubleshooting engine shutdown immediately after start-up, until the service manuals are updated.

Time Delay Relay Prevents Quick Restart

Solution A: See Service Magazine, February 13, 1984, Page 5. The article titled "Engine Will Not Restart Immediately After It Has been Shutdown" describes the problem and solution when dealing with a Type 5 3N8900 Control Board.

Solution B: Instant restarting capability after engine shutdown can be achieved only if electric starting or DC-actuated air start is provided on the engine. In such cases remove the terminal strip jumper between Terminals 27 and 28. Connect Terminal 27 to the output side of the electric starting motor magnetic switch. If a DC-actuated air start is used, remove the jumper between Terminals 27 and 28. Install the jumper between Terminals 26 and 27. See Illustration 1.

Crank Terminate Speed To Low

Solution A: This problem has been reported on 3208 and 3300 Series Engines. At low speeds (below 500 rpm) engine oil pressure may be unstable causing the oil pressure switch to close and then open for an instant. When this happens, and the crank terminate contacts of the dual speed switch have closed, the oil pressure shutoff will arm and then shut the engine down.

This problem can be solved by simply increasing the crank terminate speed setting. Crank terminate must be set at least 100 rpm below low idle rpm to insure that the shutoff system will arm.

Solution B: This problem can occur on the new junction box type electrical system if the customer adds an electrical latch on the oil pressure shutoff circuit. This would not be a problem with the standard wiring because the shutdown signal would only occur for an instant.

Engine Control Switch Or Engine Start Stop Switch Is Released Too Soon

Solution A: The shutoff system is activated when the engine control switch (ECS) is released (moved back to run position). If the ECS is released before the oil pressure comes up, the engine will shut down. Since oil pressure does not come up as quickly if the engine has not been running for some time, the ECS will have to be held longer. See Control Panel (SR-4 Generator Mounted), Form SENR4027, Page 53, "Engine Control Switch (ECS) Released To Run Position" for more information.

Do not try to make a manual control panel do the job of the automatic control panel. Some modifications will render the overspeed shutdown ineffective for the first nine seconds after starting.

To convert to an automatic control panel, install a 4W8005 Control Group. To convert to a manual control panel, install a 4W8004 Control Group. See the point-to-point wiring diagrams on Pages 66 and 67 of Control Panel (SR-4 Generator Mounted) Form SENR4027.

Solution B: The start stop switch (SSS) on the junction box used on marine, industrial or generator set engines will also cause the engine to shut down if released before oil pressure builds up.

Desig Of Customer Supplied Control Panel

This electrical system is designed to operate in conjunction with a control panel or switch gear that is not supplied by Caterpillar. If the control panel does not contain a timer to deactivate the oil pressure shutoff circuit during start-up, shutdowns will occur. If the control panel is not wired correctly, the engine shutoff system may not function at all.

Illustration 1. Energized to shutoff (ETS).