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99 Miata - fuel pump does not run unless jumper wire is in place

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Best Answer miata4me , 08-29-2017 06:11 PM

Thanks for the input guys.   I checked/cleaned a couple grounds and also set the crank sensor gap.  I reseated every connector I could find.  The car now runs so it will be headed to the track for the first time in over a year :-)

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#1
miata4me

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I just installed a rebuilt engine in my son's spec Miata.  The first thing I noticed when we went to start the engine for the first time was when he turned the key, I did not hear the fuel pump run.  The pump will run when I put the jumper wire in place.

 

Any suggestions on why the pump is not running would be greatly appreciated!

 



#2
callumhay

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Might be the fuel relay, which is under dash on driver's side. Since the pump runs, I think it would be less likely to be a fuse. Look at any grounds on the circuit as well as other sensors that are in the circuit ( maybe crank and cam sensors) . Looking at fuses, ground and fuel relay first would be what I would do.

#3
davew

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Unless the Air Flow Meter (AFM), Cam and Crank sensor senses air flow/movement, it will turn off the fuel pump off after a couple seconds.

 

Basic fuel pump wireing. The ECU grounds the relay, which turns on the pump. The jumper pin does the same thing. So if the pump runs when jumped, it is not a relay or pump problem (the output of the relay). By default the issue is in the control side of the relay (ECU, Sensors, Wires)

 

dave


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#4
miata4me

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✓  Best Answer

Thanks for the input guys.   I checked/cleaned a couple grounds and also set the crank sensor gap.  I reseated every connector I could find.  The car now runs so it will be headed to the track for the first time in over a year :-)






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