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Fuel/Engine Shutoff Solenoid

buddy

buddy

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Is the IP's fuel shutoff solenoid a common failure item?

I have two of them and now neither seems to function. Neither plunger moves when power applied.

The condition seems to cause the engine to die about 3 seconds after starting up. I had this issue a while back so I replaced it, and now its happening again, so I pulled off the solenoid and sure enough it doenst move with power applied.

Anyone just pull the plunger out?

Thanks
 
allens died/leaked more frequently than hex headed ones, plunger can be pulled and run without, just 1 less safety shutdown feature, as key off will de-energize FSD and truck shuts off from that also
 
I got the hex heads, but one of them is 10 years old and the New one seemed flimsy when I bought it, the cylinder part would wiggle after tightening it down, whereas the old one is stiff just not working either.

I think I just got a bad New one. I'll pull the plunger out for now.
 
Seem to remember Gmctd saying that plunger helps keep fuel from running down from pump after shutdown .
 
Wish I had my C clamp pliers with me. Took me a while using multimeter leads and a flat screwdriver to get the plunger clamp out, but trucks running like a champ as usual.

That function seems like they should have done away with it when they made the pumps electric.
 
Grounds? The shotgun answer I know but how are you checking the shutoff solenoid. I recently tried to check a Kubota shutoff solenoid and I messed up. You have to ground the body then supply 12V and 12V to the other wire too. One is pull in power the other is hold voltage. Not sure about the DS pumps but at least ground body of fuel solenoid good to test well.
 
On the DS IPs the shutoff solenoid is grounded in the PCM on one wire and recieves IGN power on the other. So not needing 12V on each line.

I think the truck runs a little smoother while on cruise control now, like maybe the plunger was causing it to stumble a little for the last few months.
 
To answer your original question its not a real common failure like the OPS or lift pump but a normal occasional failure. As in I have read a few threads over the years but its not real common.

Yeah, I forgot that but was trying to see if the body of the solenoid needs a good ground too for pull in vs hold just a thought. Have read the ground wire on the metering solenoid FSD harness is important to keep attached to the IP body.

The shutoff is a safety and the ground from ECM is the master kill switch for the DS IP's. The ECM actually cuts the engine off with the metering solenoid. BUT the wiring is so cross linked just about all is relayed and switched with the key switch anyway. I think both the shutoff solenoid and ECM are powered via the same node running from the key switch. Be careful of any back feeding on this circuit, weak key switch relay contacts, or trying to draw more current for something else.

Just as an example many have had the truck not shut off with the key switch due to back feeding this circuit from hardwiring the OPS/lift pump.
I had a similar issue back feeding.

I had a wire come loose in my trailer plug and the truck would stay running when I took the key out when in reverse. With key on run lots of circuits go "hot". The same node powers the ECM and the reverse lights. When in reverse gear current travels to back of truck thru transmission switch to bulb then grounds at rear. Well, when my trailering wiring shorted I would cut the key off but while in reverse the short would change change direction of current back feeding through reverse switch to common node and the ECM did not know I had turned the key switch off.
 
Thanks for all the info. Its not had any issues with the plunger gone. I might cut the plunger and put it back in just so there is not a hollow cavity there. Or I could just plug the hole and edit my PCM EPROM to not monitor that circuit, so I dont get the DTC13.

Since the shutoff and PMD run off the same IGN circuit its not exactly redundant either, except for redundant failure. The IP aint doing anyting if the PMD doesnt have power. It made a lot of sense in the mechanical pump, which seems like a much better design anyway.

I may not replace it at all.
 
The way I understand it is the ECM supplied ground is a kill switch in case of runaway ect. If the ECM can't control a runaway IP/engine. I think it must cut off fuel when it detects over governed speed??? I have read some have lost throttle control between idle and redline but thats different. The ECM could misinterpret that as WOT not a runaway. But in the event the ECM can't control runaway past governed speed it will cut fuel supply off with loss of ground. This could happen in the case of a shorted PMD or other short. Any short could-would be misinterpretted unless the on terminal of ECM had some redundant relays and diodes in the circuit and kill power switch was on the final wire to the FSOS. Since there are so many common nodes the cheapest reliable way to kill is cut the end of the circuit.
 
A shorted PMD/harness where it somehow outputs a high voltage to the IP without getting the signal from the PCM seems like the only real problem, and we know PMDs can do things like that.

I might replace it if I can pick one up for $25, but at $125-$150, its eating into the ATT fund :)
 
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