ritcheyvs
Veteran Member
If I remember right, some here thought it had to do with the shutdown solenoid slamming closed to hard on the 05-08 models, damaging the gears. Not bad fuel
Here's what I think I know about this.
(1) The "old" version of the stop solenoid used an external solenoid on the right side of the engine and that solenoid physically operated the external, manual stop linkage. There was an 8-sec 12v pulse provided by a timer relay that powers/operates that solenoid when the key switch was turned off. The force from that old version was limited to the force produced by the solenoid under power.
(2) A "new" SS version was phased in at different times between 2005-2008 with different models getting the new version at different times. I think the bigger engines got the new version first. This new version uses a solenoid on the front of the engine. That solenoid pushes directly on the IP rack and is spring-loaded to force the IP rack full aft (off/zero fuel). For the engine to start and run, a 1-sec 12v "pull" pulse to the solenoid retracts the solenoid (freeing the IP rack) and continuous 12v "hold" voltage keeps it retracted until the engine is shut down (via the key).
(3) I suspect the failures are caused by the momentum of the new solenoid (built up by the spring force) as it smacks the IP rack on shutdown. The rack (and the gears and plungers) should be free to move but if one of the plungers is under pressure (injection stroke) as the solenoid smacks the rack, that plunger could resist rotating and break a gear tooth. The IP plungers are lubricated by fuel so fuel quality could be a factor but I doubt it. Otherwise IP plunger wear would be a common problem.
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