Hi
I have what may appear to be a stupid question. My old Nissian diesel had an air choke that shut off the motor when you stpped. How do/does the 6.5 TD shut down? Does the PCM just cut the air flow? Or does the PCM remove power from a circut that kills it?
Thanks
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I have no idea on my '93 mechanical but on the EFI contolled trucks I'd say the ECM doesn't send a signal to the fuel solenoid to close the plunger and fuel is ceased.

I always knew diesels get shut off by shutting off fuel delivery at the pump

The electronic and mechanical stanadyne pumps both have a fuel soleniod that slams shut when power is not applied. On the electronic pump its the thing that looks like a stack of quarters that screws into the drivers side front of the pump. On the mechanical pump its the blade connector on top mid pump.

I challange you to test that out. hrjack showed me that if you unplug the ESO on a DS-4 it takes two minutes to shut it down from fuel stoppage. That's the EFI pump.

Is that the elec or mech pump he's reffering to? I assume its the elec because i don't see any other way to shut down the mech. I guess on the elec it will run on the housing pressure and whatever fuel is left in it, but if you take power away from the PMD, we all know what happens when you piss that thing off!:bleah:

Exactly, and what is the PMD?
An amplifier for the ecm signal to squit the fuel in the hole.

Fuel shutoff solenoid in the DB series is mechanical, forcing the fuel metering valve in the distributor head to the closed position.
At power-on, the solenoid retracts, allowing metering valve to assume the idle position, further allowing the throttle shaft\levers\rods to rotate the valve, as required, metering fuel into the pumping plungers - I think............

PCM shuts down in the EFI trucks.

I challange you to test that out. hrjack showed me that if you unplug the ESO on a DS-4 it takes two minutes to shut it down from fuel stoppage. That's the EFI pump.QM's right, I had a fellow tech try that, he unplugged it and said 'now crank it, it won't start'. Oh yeah I said? It will start, and stay running if you unplug it, not for long, but until the fuel in the transfer pump/galleries is exhausted.

The ESO is a secondary shut-off mechanism, primary is to cut power the the PMD, so no fuel is delivered, the ESO is just a safety feature incase the FSOL or PMD fails to shut off.