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Project Shrek: electric riddle

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Old 03-01-2010, 12:36 PM
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GeorgeK
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Default Project Shrek: electric riddle
OK, we have ignition, we have a turning engine, but we had to circumvent one problem: The fuel pump does not get power. It is strictly a current issue, as powering it directly works.
Relay checked, lines checked, DME exchanged, DME relay checked, alternator checked, battery checked, no dice. We thought of an alarm issue, but it seems weird to have only that isolated.

It seems that when starting the car, the pump gets power for half a second and then cuts right away, as we have one roar from the engine and it dies right away.

So, who will crack this challenge?
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Old 03-01-2010, 12:46 PM
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Indycam
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If you run a hot wire with a fuse from the battery to the pump , will the pump stay on and the engine keep on running ?
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Old 03-01-2010, 01:06 PM
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Flywheel sensor? I thought the pump relied on a certain rpm from the flywheel sensor to run after its primed?
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Old 03-01-2010, 01:37 PM
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GeorgeK
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Hotwire to the pump will keep it on and the engine runs perfectly.
Shouldn't a bad flywheel sensor cause more trouble than just the fuel pump power?
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Old 03-01-2010, 01:43 PM
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If you jumper the dme relay does the pump keep on running and the engine run ?
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Old 03-01-2010, 01:46 PM
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"No" on the DME relay jumper.
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Old 03-01-2010, 01:49 PM
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No the pump does not stay on and the engine stops running ?
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Old 03-01-2010, 01:56 PM
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GeorgeK
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DME relay jumped, fuel pump kicks in for half a second then stops. Engine stops.
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Old 03-01-2010, 01:57 PM
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darth
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Dear GeorgeK

"We thought of an alarm issue, but it seems weird to have only that isolated. " The way I understand it, the immobiliser function is accomplished by disabling R41 (DME/fuel pump).

Bill
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Old 03-01-2010, 02:00 PM
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GeorgeK
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BUt, if the alrm disables the fuel pump and the DME; we should have no spark, air flow meter, i.e. a non running engine?
Here it is only the fuel pump that is not powered.
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Old 03-01-2010, 02:01 PM
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Indycam
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Originally Posted by GeorgeK
DME relay jumped, fuel pump kicks in for half a second then stops. Engine stops.
Is there voltage at the dme relay jumper to the fuel pump after the pump stops ?
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Old 03-01-2010, 02:04 PM
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GeorgeK
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I don't know. I'll ask my mechanic to check. Gut instinct says yes because other DME functions still work, but I don't know .
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Old 03-01-2010, 02:06 PM
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If you run a hot wire with a fuse , to the dme relay leg that runs to the fuel pump , does the fuel pump run and keep on running ?
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Old 03-01-2010, 02:16 PM
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Dear GeorgeK

"we should have no spark" That is not the way I understand it, you should still have spark just no fuel pump. Are you using a 2 or 3 lead jumper?

Bill
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Old 03-01-2010, 02:20 PM
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Originally Posted by darth
Are you using a 2 or 3 lead jumper?
If he is getting the motor to run with a jumped dme relay ,
he must be doing the jumper correctly ?
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