Sounds like a small fuel leak at the EHA. It is easy to replace so it might be just as well to replace it due to the leaks and see what happens.

Other than that look at the article on Engine controls in the DIY section to see how to view the control signals (current flow).

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician