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Sam Powell
Supercharged
Joined: 04 Jun 2006
Posts: 3163
Location: Gaithersburg MD
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Post subject:
Where did my fuel pump whine go?
(Tue Sep 07, 2010 12:56 pm)
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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_________________ A REAL professional is someone who knows when to hit it with a bigger hammer.
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Dart270
Board Sponsor & Moderator
Joined: 21 Oct 2002
Posts: 9592
Location: Blacksburg, VA
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Post subject:
(Wed Sep 08, 2010 5:58 am)
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I thought your pump was in the tank and making no noise anymore??
Lou
_________________
Balancing out the driver's weight for more than 50 yrs
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Sam Powell
Supercharged
Joined: 04 Jun 2006
Posts: 3163
Location: Gaithersburg MD
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Post subject:
(Wed Sep 08, 2010 8:00 am)
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You could still hear it run for 5 seconds or so when you first turned the ecu on.
Sam_________________ A REAL professional is someone who knows when to hit it with a bigger hammer.
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Matt Cramer
Board Sponsor
Joined: 01 Nov 2002
Posts: 1516
Location: Oxford, Georgia
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Post subject:
(Wed Sep 08, 2010 11:22 am)
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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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Sam Powell
Supercharged
Joined: 04 Jun 2006
Posts: 3163
Location: Gaithersburg MD
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Post subject:
(Wed Sep 08, 2010 7:43 pm)
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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_________________ A REAL professional is someone who knows when to hit it with a bigger hammer.
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Matt Cramer
Board Sponsor
Joined: 01 Nov 2002
Posts: 1516
Location: Oxford, Georgia
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Post subject:
(Thu Sep 09, 2010 12:36 pm)
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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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Sam Powell
Supercharged
Joined: 04 Jun 2006
Posts: 3163
Location: Gaithersburg MD
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Post subject:
(Thu Sep 09, 2010 1:35 pm)
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But it does not fail to run. It only fails to turn on early. It runs fine after that.
Sam_________________ A REAL professional is someone who knows when to hit it with a bigger hammer.
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Matt Cramer
Board Sponsor
Joined: 01 Nov 2002
Posts: 1516
Location: Oxford, Georgia
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Post subject:
(Fri Sep 10, 2010 7:03 am)
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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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