Posted: 9/15/2011 5:46:19 PM EDT
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I'm well versed in gas engine, but don't have to much diesel experience. I was talking a friend through an ignition switch rewire on on old fork lift today and I realized that I don't know how to stop a diesel engine. Gas is simple, remove the spark and thats that. As for diesel? I figured fuel pump, but that is mechanical on this forklift. Some asshat had tried to hotwire the lift so replacing the switch was not easy for him. I was able to walk him through finding the battery wire, ignition wire (if thats what its called on a diesel) and crank wire. He got those connected and was able to get it started, but he told me there were two more wires. This thing is late 70's early 80's bare bones. No lights or anything electronic. Any ideas on what those wires are for? Also, what does the ignition wire actually do in a diesel? |
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Ignition wire will heat the glow plugs if it has them, and feeds power to the starter relay and/or solenoid.
To kill a diesel, you cut the fuel supply, since you really "can't" burn a diesel down by running it lean. ETA: Depending on the age of the fork lift, it will either have a "Pull-to-stop" cable, or when you turn the key off, the ignition switch to a solenoid on the pump to shut off fuel flow. |
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Ignition wire usually energizes a solenoid to allow fuel flow from the injector pump.
Many older industrial diesels have a simple manual shut off. You may have a handle to pull or maybe pull up on the gas pedal. In this case the ignition wire simply turns on the charging system and any other electrical systems that run with the switch on. |
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Quoted: Ignition wire will heat the glow plugs if it has them, and feeds power to the starter relay and/or solenoid. To kill a diesel, you cut the fuel supply, since you really "can't" burn a diesel down by running it lean. ETA: Depending on the age of the fork lift, it will either have a "Pull-to-stop" cable, or when you turn the key off, the ignition switch to a solenoid on the pump to shut off fuel flow. So a mechanical pump diesel will have a solenoid that shuts electronically to stop fuel flow? Would the ignition wire being hot open this valve, and being closed shut it? |
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Cut the fuel to stop a diesel.
What the other wires are for beats my. Could be oil pressure sending unit. No oil pressure no start. A diesel always runs "lean" On average a diesel has around 1000% more air in the cylinder than needed for combustion. One reason why diesels sound the way they do. Always knocking. They run on detonation. |
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Quoted:
Quoted:
Ignition wire will heat the glow plugs if it has them, and feeds power to the starter relay and/or solenoid. To kill a diesel, you cut the fuel supply, since you really "can't" burn a diesel down by running it lean. ETA: Depending on the age of the fork lift, it will either have a "Pull-to-stop" cable, or when you turn the key off, the ignition switch to a solenoid on the pump to shut off fuel flow. So a mechanical pump diesel will have a solenoid that shuts electronically to stop fuel flow? Would the ignition wire being hot open this valve, and being closed shut it? That's a question I can't answer. Depends on which lead you hook up hot on the solenoid. 
I'm a gas engine guy, too, and I'm in the tractor business, but with parts, not tech. Sorry if I'm not of better use. 
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There are two ways to shut the diesel engine:
- Cut the fuel supply; - "De-compress" it; The way the "de-compression" works is the diesel cylinders are fitted with valves that are closed during normal operation, and open at shut-off, thus reducing cylinder pressure and in turn preventing fuel detonation. |