MSB asked if I wished to offer a rebuttal?
Okay.I see it like this. Some people are good mechanics, and some are not. I can't judge what someone else is capable of doing. There is nothing magic, nor is there there anything overly complicated in a Stanadyne "Roosamaster" fuel injection pump. Basically, it is two fuel pumps joined together - one a high pressure plunger pump and the other a low pressure vane pump. Controls are added for RPMs, timing advance, and the amount of fuel delivered. If you are a skilled mechanic - and like fixing things, figuring things out, and learning - working on a injection pump is no more complicated then rebuilding an engine, a cylinder head, transmission, magneto, etc. Seems to be a lot of emphasis on a "hands off" attitude towards injection pumps - which is good for the pump shops. I see a lot of this as absolute nonsense. The Stanadyne rotary pump comes in various forms. The DB2 pumps used on autos - like the GM 5.7s,6.2s and 6.5s - and also the Ford-IH 6.9s and 7.3s - can be much harder to work on than the pumps used on tractors. With the DB, JDB, etc. pumps used on tractors - you can pull one apart, properly diagnose what needs to be replaced, put back togeher, set fuel delvery and timing advance with very few special tools. That, because you have the whole tractor and can adjust the pump on a running engine. A pump shop does NOT have that luxury and must rely on a pump test-stand that simulates engine conditions. "Rebuilt" pumps, generally speaking, are NOT rebuilt. Many wear items are reused, not renewed. When taking a pump apart, the close fitting parts are checked by feel and visual appearance - not by special measuring tools. Worn parts are usually very easy to see. Fuel delivery is set by using a simple 2" micrometer. Low-side fuel pump pressure set by using a 150 PSI gauge. Timing is checked on a running engine. This can be done with a plastic timing window or a gas-engine style timing light hooked to a magnetic pickup. I don't adhere to the "clean room" story either. Nothing that relies on close-fiting metal parts does well with dirt. That includes, injection pumps and other forms of hydraulic pumps. That being said, I've done many out in the field and they worked fine - when done with care. The reality is - most rotary pumps need a minimum of parts and time to fix properly. Often all that's needed is an $8 pilot tube, a $12 metering valve, a $14 seal kit, a $14 set of pump vanes and liner, and - if desired - a $35 update to elimate forever the plastic governor ring.
It takes a hour - start to finish - to do the job right if you have experience. If not - maybe, with care, it will take you four hours instead. It's a personal choice, I guess. You might get the satisfaction of learning something new and fixing the pump yourself - for less than $100 - and maybe less than $50. Or? Pay a pump shop $400 - $700 - let them do the work and then call yourself a mechanic. On some Stanadynes you will need the special Bristol wrench to remove one screw - and it will cost you $10. The plastic timing window will also cost you $10. Those are the only special tools you might need. That's my take on it - and I suspect that some people who say "only the experts" should do it,
are hestitant to do it themselves - and therefore don't like seeing anyone else do it. It seems, at least to a degree - tractor collectors and enthusiasts tend to be a "hands on" community - so why preach "hands off" with this mechancial component?
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