"The accumulator is still intended to hold a certain amount of fuel to facilitate cold-starting."

Not entirely true according to the Bentley 240 manual, which says: "the accumulator absorbs fuel pressure surges and helps retain residual fuel pressure when the engine is off".

However, the subject of this thread is an alleged mechanic's assertion that residual fuel pressure can be expected to hold overnight. I don't agree with that, and find nothing to support it in:
• Bosch K-Jet manuals
• Bentley 240 manual
• Bentley Bosch FI manual

The Bentley 240 specification for residual fuel pressure duration is "...at least 20 minutes", noting that a rapid pressure drop "(usually in less than 3 minutes) the problem is most likely in the fuel pump check valve or the accumulator".

Based on what I could find in the manuals, I believe that the idea of maintaining residual fuel pressure overnight is a myth, with or without the accumulator.


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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.