I've been thinking about your question this evening and it dawned on me that there IS something you can do with your injection pump if you want it operate at maximum efficiency. Change the pump thermostat. I'm not sure what kind of half-life they have but after discussions with friends who've owned and maintained this particular vintage it's probably cheap insurance and will pay for itself in fuel savings. I had to do it on my 280 SEL when I repaired the plunger underneath the thermostat. My MB mechanic friend said that he was getting crappy mileage, around 14 mpg when he changed his and his fuel economy shot back up to 20 mpg. The thermostat bulb sits in the thermostat housing and pushes down on a plunger that determines air-fuel mixture. The further it pushes down, the leaner the mixture. Problem is, when the thermo/bulb gets old it can't push down as far resulting in richer fuel mixtures and poorer mileage. The thermostat is located toward the rear of the injection pump and has two small cooling hoses attached to it. It is held on with two screws and comes off easily. Inside this housing you will find the thermo/bulb thingy. Do NOT remove the steel pin on the bulb or you will render it useless. A new bulb will cost you about $40.00 or so from your friendly MB dealer. Replacing it is pretty cut and dried, just the reversal of removal. Make sure you mop up coolant that leaks down on any of the pump innards. With this little bit of maintenance you can make sure your 280 is getting all the bang for its buck. Byeee.
Thom

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1987 300E
1967 Jaguar E-type Series I, 2+2