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  Fuel Pump Relay Drive line 12v or 5v?

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Fuel Pump Relay Drive line 12v or 5v? by breeblebrax
Started on: 01-05-2015 08:51 AM
Replies: 6 (219 views)
Last post by: breeblebrax on 04-10-2015 07:45 AM
breeblebrax
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Report this Post01-05-2015 08:51 AM Click Here to See the Profile for breeblebraxClick Here to visit breeblebrax's HomePageSend a Private Message to breeblebraxEdit/Delete MessageReply w/QuoteDirect Link to This Post
Skipping a long sorted story, my mechanic shorted the Fuel Pump Relay Drive wire to chassis ground.
(Yes, he literally removed a section of insulator and ran a wire directly from the Green/White wire, to the chassis ground)

I believe the computer is now damaged as I can no longer hear the fuel pump activate when I turn the ignition to the on position.
(I have removed the jumper wire) and I see 4.5 volts on this line when the ignition is in the on position. I believe it should be 12v and only be there for 2 seconds.
Is this correct?

If it is only 4.5v and not dropping to 0 after 2 seconds, is it likely that the ECM has been damaged by the grounding out of the Fuel Pump Relay Drive line?

Thanks,
Chuck
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olejoedad
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Report this Post01-05-2015 09:59 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
12v.
Your mechanic owes you an ECM.
You need a new mechanic.
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breeblebrax
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Report this Post01-06-2015 07:43 PM Click Here to See the Profile for breeblebraxClick Here to visit breeblebrax's HomePageSend a Private Message to breeblebraxEdit/Delete MessageReply w/QuoteDirect Link to This Post
As I thought. Thanks for your quick response!
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breeblebrax
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Report this Post01-27-2015 07:55 PM Click Here to See the Profile for breeblebraxClick Here to visit breeblebrax's HomePageSend a Private Message to breeblebraxEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ok, new computer in place. 12v on signal. All seems to be good. Car wont start...
I can not catch a break on this car...

Will check fuel pump fuse when it warms up a little. Working in the driveway in Michigan.

Cheers,
Chuck
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Gall757
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Report this Post01-27-2015 08:02 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
If you want to trouble-shoot it...tell us what fiero you have.
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jaskispyder
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Report this Post01-28-2015 12:51 PM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you put 12V to the fuel pump test port in the ALDL, does the fuel pump turn on? Will the car start in this situation?
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breeblebrax
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Report this Post04-10-2015 07:45 AM Click Here to See the Profile for breeblebraxClick Here to visit breeblebrax's HomePageSend a Private Message to breeblebraxEdit/Delete MessageReply w/QuoteDirect Link to This Post
And finally a result.
I put in a new Fuel Pump relay last year. It is now bad. I took the relay apart and and found significant corrosion.
Car now runs great, except for one issue.

It now stutters at a specific circumstance while driving.
1) After you have gotten up to speed at about 2000-2500 RPM until you reduce pressure on the peddle, increase pressure on the peddle, or downshift.

This car has all new stuff, plugs, wires, ignition, fuel pump, fuel filter. air filter, you name it.

Anybody got a clue on this?

Thanks,
Chuck
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