Fuel pump only works with diagnostic jumper - Mazda MX-6 Forum
 
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post #1 of 11 (permalink) Old 4-4-03, 23:38 Thread Starter
 
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Fuel pump only works with diagnostic jumper

My pump stopped working and now it only runs if I run a wire from fuel pump to ground at the data link connector next to the battery. You can hear the fuel pump running when you use the wire, but I don't hear the fuel pump at all. With the wire I can drive fine(except I went for a longer trip and my car died and I had to get towed, but now it is working again). Without it, I can't start. I'm thinking it's electrical but I'm not sure what and where. Any ideas?

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post #2 of 11 (permalink) Old 4-5-03, 1:26
 
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Well the PCM demands an ignition signal before it will turn the fuel pump on so i would start there to be sure it's getting that signal first. You will need a wiring diagram to trace this down im afraid.
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post #3 of 11 (permalink) Old 4-5-03, 20:59 Thread Starter
 
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I think it's getting an ignition signal because the car actually starts when I force the pump to turn on. For some reason, the PCM is deciding not turn on the pump and I'm not sure why. The wiring seems to be fine. The only reason I've ever heard for the computer to not turn on the pump is that it thinks there's no oil pressure. I haven't check this yet, but what else would make the computer not want to turn the fuel pump on?

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post #4 of 11 (permalink) Old 4-6-03, 0:44
 
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I'm not talking about ignition. I'm talking about the signal from the ignition to the PCM. You can lose that signal and still get spark. When you jump the fuel pump you bypass that signal.
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post #5 of 11 (permalink) Old 4-8-03, 9:06
 
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pm me your email and i will send you a wiring diagram, it is better than the haynes or chiltons.

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post #6 of 11 (permalink) Old 5-6-10, 7:37
 
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i had that problem too but mine was a simpler fix. my vac just sucks in the fuel
not sure if the pump is working but my car starts no problem without having the wires jumped. i ended up shutting down my tach by fucking around with those wires
so be glad there is a thing called disconnect battery try again
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post #7 of 11 (permalink) Old 11-8-12, 17:47
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Sorry for reopening a very old thread but I have exactly the same problem, with my 93 AU Spec 626.

From reading here it seems that is you lose one of the crankshaft sensors the ECU won't switch on the fuel pump, is that correct?

Do we know which one is normally at fault the dizzy one or the front pulley one?

I really don't want to buy yet another distributor...
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post #8 of 11 (permalink) Old 11-9-12, 8:42
 
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I think the signal is from the distributor, but I'm not 100% certain. You should be able to check if you read the codes. IIRC it's code 3 or 4 for the sensor in the distributor. 1993-1995 Engine Controller Malfunction Codes

Actually, it can't be the sensor on the crank pulley, because 93 and 94 cars will run (though not quite as well) even if that sensor is disconnected.

I think Australian cars don't have a check engine light, but there is a way to read codes in Autralian cars, using an LED to connect the ten and gnd pins in the diagnostic box, IIRC.
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post #9 of 11 (permalink) Old 11-10-12, 2:52
 
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I had this exact same problem and jumper wire solution. Turned out to be the nuetral safety switch on the auto trans.
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post #10 of 11 (permalink) Old 11-11-12, 19:17
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I'm sure I updated this from Home...

The Distributor looks ok, I haven't checked the crankshaft one yet.

Does anyone have a logic diagram for the ECU so I can see what else would cause the ECU not to enable the pump.
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post #11 of 11 (permalink) Old 11-18-12, 21:46
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OK I don't have a crankshaft one, so sign of it or any wiring so I assume I never had one.

So does anyone else know what would cause the ECU not to power up the fuel pump.
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