Steve, I've never timed an injection pump, but thought I would contribute this letter and response from the March/April 2001 issue of "The Star." It sounded promising, so I hope it helps.

Q: On my 1982 300SD's fuel injection pump, I've tried to adjust the "start of delivery" using the bent overflow pipe, but I don't know when to start timing the drips. Pumping the manual fuel lever produces continuous fuel flow out of the pipe, and the frequency of drips slows steadily. Until the drips stop, there no steady frequency. I'm also having trouble finding a 45-degree offset box wrench to loosen the injection pump; is there an alternative?

A: The drip timing specification calls for one drop per 10 seconds, but it's easier and less messy to time the pump using air instead of diesel fuel to set the beginning of delivery. Make up two clear hoses; connect one to a banjo fitting the same as the injection pump fuel inlet; connect the other to a cut-off injection line (or the bent tube you use for drip timing). Proceed as with drip timing, but instead of pumping fuel with the hand pump, blow air into the injection pump fuel feed. Stick the drip tube hose into a glass of water, and watch for when bubbles stop coming out of the hose. As you push the pump toward the block, it will become harder to blow air through the hose until the bubbles just stop. Lock the pump down there, and recheck by rotating the engine to 24 degrees BTDC on number one cylinder and blowing again. This method is accurate and repeatable within 0.5 degree of crankshaft rotation and is much cleaner than pumping diesel fuel.
To loosen the three nuts and one support bolt at the back of the pump, we use a regular box-end wrench and a wobble socket on an extension. The only unusual thing is that the throttle is supposed to be held full open while timing the pump.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References