Merlyn wrote:Thinking back a few years I went out to several engine breakdowns ( non starters ) whereby on an earlier Bosch course we were told that the latest diesel fuel sulphur content in LFO setups caused on certain types of inline pumps only rack bar seizures to occur with the rack bar in the stop position thus creating a non start situation.
Caterpillar had a similar problem with the single rack bar that controls all the individual pumps in a self contained block assembly jamming in their "V" type engines such as the the 379, 398 & 399 series engines. However their problem wasn't so much with the lack of sulphur in the fuel, because Cat's have a very discerning palate when it come to the fuel they drink and they only like the best, rather because of the pump design without any kind of spring release on the pinions of the individual injection fuel pump plungers therefore if an individual fuel pump were to seize the rack would jam. A seized plunger besides prevent the engine from starting will more often cause the engine to overspeed with disastrous results. A jammed rack also prevents the mechanical or electronic overspeed safety shutdown systems from working so the engine will run away until it destroys itself if the engine cannot be stopped by some other means. In order to correct the problem without a complete redesign of the fuel pumps Caterpillar installed latched spring loaded dampers in the air intake manifolds. If the engine were to overspeed due a jammed fuel rack an engine driven speed switch or remote kill switch would activate the dampers trip coils causing the dampers to close starving the engine of air. Depending on the position of the rack the engine would sometimes continue to run, all be it very roughly, giving an opportunity to shut the fuel off and prevent parts being thrown the engine space.
Troubleshooting 101 "Don't over think it - K.I.S.S. it"