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Old 03-16-2006, 01:40 PM   #1
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Default Thoughts on the fuel pump...

I have been contemplating the Fuel Pump and this is what I am thinking about doing.

From my reading I have gleaned that the MS FP circuit is designed to add a ground to get it running.

The stock ecu provides 12v to get the FP running...

The AFM completes the opening circuit by completing a ground...

Can we wire the FP to the ignition sourced 12v+ and use the MS to complete the ground through the AFM wiring?

Just tossing ideas out... to see what will work.... and making sure I understand what is up...

Chris
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Old 03-18-2006, 05:17 PM   #2
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I'm just going to jumper the FP to GND in the diagnostics box under the hood. Too easy. And easily reversible. markp from miata.net suggested it. I don't really see any purpose to doing it in an any more complicated way.
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Old 03-18-2006, 06:14 PM   #3
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Won't that remove the fuel kill ability in an accident?
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Old 03-18-2006, 06:24 PM   #4
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Yes, but so would all other proposals, since they rely on the MS, unless there is an accident fuel shut off feature on the MS I don't know about.
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Old 03-18-2006, 09:04 PM   #5
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you just gotta remember to turn the key off when you get into an accident :gay:
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Old 03-20-2006, 10:03 PM   #6
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So let the MS ground a relay...
And the relay can supply the 12V to the FP as the Mazda Gods intended...
Standard SPST 12V 15A should do [email protected] crapshack...
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Old 03-20-2006, 11:25 PM   #7
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I think 1.8L Maf car get it easy.. I just let the stock ECU deal with the fuel pump Even with the Maf unplug.. the pump still work just fine.
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Old 07-06-2009, 01:00 AM   #8
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Quote:
Originally Posted by Al Hounos View Post
I'm just going to jumper the FP to GND in the diagnostics box under the hood. Too easy. And easily reversible. markp from miata.net suggested it. I don't really see any purpose to doing it in an any more complicated way.
Sorry for the ridiculous thread necromancy, but is this an acceptable solution instead of running wires to the MS from the fuel pump relay under the dash?

Thanks

Last edited by albumleaf; 07-06-2009 at 01:47 AM.
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Old 07-06-2009, 01:11 AM   #9
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Quote:
Originally Posted by Al Hounos View Post
I'm just going to jumper the FP to GND in the diagnostics box under the hood.
I drove for 15k miles like that... never crashed, but hopefully in my last few conscious moments, I'd remember to turn the key to off. It is the "easiest" way.
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Old 07-06-2009, 01:34 AM   #10
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Hmmm.

I've always had mine wired to the MS. It's just one wire from the fuel pump relay under the dash. The upshot of this is that the last time I crashed, despite the fact that I was killed instantly, the fuel pump did not continue to run so my family was able to have an open-casket ceremony.

Yeah, running it with a jumper in place will work so long as the jumper does not fall out, and so long as your next of kin don't come after us for approving your bypass of an OEM safety device.
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Old 07-06-2009, 01:48 AM   #11
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I appreciate the heads up, thanks!

edit: I still have the AFM sitting there connected. I understand that the fuel pump turns on in response to the AFM, so this should work for now right? I think I'll just leave it for now while I sort out other stuffs.

edit2: Yet another idiotic question, as far as splicing wires/etc goes -- I'm a complete newbie to this stuff. I've done some soldering for some other projects so I'm not totally in the dark, but what's the best way of tapping into these things? Also did you just run the wire behind the console and around the carpet? Nothing fancy like through the dash right?

()^4444444444
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Old 07-06-2009, 02:09 AM   #12
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Quote:
Originally Posted by albumleaf View Post
I've done some soldering for some other projects so I'm not totally in the dark, but what's the best way of tapping into these things?
For non-critical, low voltage circuits, I use a lot of these:

You place it over the wire you want to tap, squeeze it with pliers, and then you can plug a connector into it. There's also a blue one for 14-18ga wire.

For critical circuits, I'll either solder it, cut the wire in half and then connectorize it with Molex 062 or similar, or something else along those lines. However there are probably 30 of those splices in may car in various places, and I can't recall ever having had one fail.

Quote:
Also did you just run the wire behind the console and around the carpet? Nothing fancy like through the dash right?
I expect that I probably used a coat hanger to pull it behind the airbox in the center of the dash. Been a while, but that's typically how I run wires from one side to the other back there.
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Old 07-06-2009, 02:17 AM   #13
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Super Moderator is a wholly appropriate title.

Looking into subscribing now, this forum is all too invaluable not to give a bit back.
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