This afternoon, I went out to drive the Dart to the gym, and when I turned the fuel pump switch and the ECU on, the fuel pump whine was not there. There car started anyway. What is up with that? Did the pump just get quiet all of a sudden, or is there some setting in the MS I for fuel pump activation before start that somehow or other changed?
Sam

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I thought your pump was in the tank and making no noise anymore??

Lou

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Home of Slant6-powered fun machines since 1988

You could still hear it run for 5 seconds or so when you first turned the ecu on.

Sam

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Fuel pump activation is automatic; there's no setting to make it behave differently - it could be some components in the fuel pump "wore in" and brought noise levels down.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

The fuel pump does not run before start up anymore. I checked that out. I turned the key and ecu on, and sure enough, no fuel pressure at the gauge. Cranked, and it starts after a few cranks to build pressure, and it carries the correct fuel pressure. Then, when I hit the MSD switch and kill the engine, I hear the old familiar fuel pump noise for a few seconds, and then it cuts off just like always. So, something has changed. The ECU is no longer sending the fuel pump the message to pump first. Do you think a circuit is going in the board. Could a component be not properly functioning now?

This reminds me too much of my failing dash gauges.

Sam

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It could be a damaged fuel pump drive circuit. Do you have a Stimulator board you could use to check it? Also, check the voltage at the pump itself and see if it gets 12 volts for a couple seconds when you turn the key on. If it's getting power but not turning on, it's the pump.

I'd expect the relay to be more likely to fail than the parts inside the MS, since the internal circuit is all solid state and the relay has moving parts.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

But it does not fail to run. It only fails to turn on early. It runs fine after that.

Sam

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Seems more likely to be the relay than anything else at this point. Solid state parts usually either work or they don't; relays can become slow or intermittent.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair