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I replace Bosch pumps when they fail. I had a shop wagon 280TE that the fuel pump screamed for years.
Many cars have pumps that are a real liability and real diagnostic techniques have been adapted to quantitatively judge these risky pumps.
I looked for an example of a MB pump but there were none. There were plenty of GM examples and I will enclose one. This technique has been refined on Domestic cars and lots of data can be defined from the scope patterns. The pattern is taken by placing an inductive ammeter on a power wire. It represents curent over time. The humps indicate peak current at each commutator segment. Characteristic shapes of particular "humps" can identify a complete revolution and thus determine rpms. Aftermarket sources have compiled tables of rpm values for these perishable pumps.
Here is an example: Before I explain any further I will show the pattern and see if there are questions. This is a GM pump:
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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Last edited by stevebfl; 05-30-2004 at 10:58 AM.
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