At OERM we have ex USAF GE 45 Ton locomotive number 7441. This locomotive is used as a yard switcher and does a quite admirable job. Unfortunately, it also has some slight issues. Specifically, as the throttle is opened, the number 1 prime mover rpm drops from idle to perhaps 50% of idle speed, and sounds like it is headed for a stall. If the throttle is kept at that position for perhaps 10 seconds or longer, the prime mover breaks out of the stall and will increase rpm to what I believe is the appropriate rpm for that throttle position. The locomotive has two Cummins inline 6 cylinder type H motors with single disc fuel pumps without speed governing.

Does anyone here have any ideas or perhaps suggestions on how I can go about figuring out the root cause?

The 44 tonner at Rio Vista had fuel issues several years ago. You might ask up there. Seems as if we discovered it was sucking air due to a leak in a fuel line. Andy

I am assuming you have a mechanical fuel system but am not familure with the particular equipment you have. if you have not already start with the basics. Check the fuel, fuel filters, fuel lines, and fuel pump. If any of these are partially plugged or sucking air you may find the problem rather easily. After these potential problems have been eliminated you will have to go on to items like the injection pump and injectors. Be sure none of these or the lines going to and from them are leaking. Usually you will find the problem in one of these areas and it is frequently harder to find than fix.

John Bohon

we have had the same issue on our 25 tonner from time to time. The quickest way to determine if the fuel pump is the problem or if it is in the filters, line or tank before the fuel pump is to to disconnect the fuel line and return line. Attach temporary lines and put them into a 5 gallon can of diesel fuel. If the lines, filters or tank are the issue the engine will run fine on the temporary hookup. If the pump or further up line is the issue, you will know this as well.

Should the check for leaks on the suction side prove negative, perhaps you are beginning to experience a common single-disc & double-disc problem: the scoring of the distributor plate. Often becomes a problem if the engine is run out of fuel and an operator cranks the engine over for quite a bit with no fuel. The mating surfaces can scratch and score easily as the fuel oil is the lubricant between the plates. The pump will supply fuel at idle but will leak by as the engine rpm tries to increase and the pump is lagging behind the injector demand. Some of the older fuel injection repair companies will tackle a rebuild project like that but they are tough to find these days.

You might want to hunt down an older PT-equipped engine that has been retired and convert over to PT. Some H-series engines required a long-nose adapter to drive the pump, others just needed a mounting bracket. I have been told by several industrial locomotive rebuilders that they just pull out the H engines for scrap to keep the locomotives supportable by the industrial users of today. They re-power with a newer engine. Perhaps someone in that field would be a good contact. The PT system is a much improved method of fuel delivery ove the older disc systems.

Rob