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Discussion Starter #1
fuel pump isn't turning on when turn key to run position.

happened out of no where with no signs of problems beforehand.

- checked fuel pump - good
- ran thru this entire troubleshooting list at least 3 times http://www.stangnet.com/mustang-forums/threads/fuel-pump-not-working.860213/

after pulling almost the entire car apart troubleshooting and replaced the fuel pump relay, computer and ignition switch it still wouldn't turn on. I went inside for a break not knowing I left the key in the run position. went back outside to the car and the fuel pump was running?!? put the car back together and drove it around for awhile. parked it in the garage. went to start it up the next day (today) and back to the same problem.

here's where I am

rechecked the fuel pump by running test leads from the fuel pump connector straight to the battery (have hatch floor cut out for easy fuel pump replacement and battery relocated to trunk) - GOOD

jumped the fuel pump test connector and I have 12 volts at the fuel pump connector. checked with multimeter and test light.

checked the ground at the connector and it's good aswell.

What could cause this? I ran some test leads straight from the fuel pump to the fuel pump pigtail connector and still no fuel pump.
 

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the pump only runs for a second or two in rUn, and not always.

the ecm grounds the relay coil.

you can use a test light to battery pos, and the ground control, and see if the light turns on when it calls for a prime.

its a very simple circuit.
 

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Discussion Starter #3
the pump only runs for a second or two in rUn, and not always.

the ecm grounds the relay coil.

you can use a test light to battery pos, and the ground control, and see if the light turns on when it calls for a prime.

its a very simple circuit.
so connect the test light to battery pos and check for a good ground coming off of fuel pump connector? not sure I understand.
 

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yes, the coil ground

unplug it and stick the light probe into the proper female pin

do you know how relays work?

two pins, will carry the line and load it is switched

two pins will be power and ground for the coil

you want the ground.
 

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Discussion Starter #5
ok just unplugged the fuel pump relay and jumped the orange/lt blue wire (always hot) to the pink/black wire (12v to fuel pump) and nothing. I completely bypassed the relay that way so it has to be the orange/lt blue wire. is it possible that the fuse link in the orange/lt blue wire coming off the solenoid is bad even though it lights up the test light and shows 12v on my multimeter but won't power the fuel pump?
 

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Discussion Starter #6
found the problem. replaced the fusible link from the solenoid to the fuel pump relay and now I had no power at the relay (orange/lt blue). so I traced it back to this connector under the drivers side kick panel. had 12v on the side coming from the solenoid. no 12v on the relay side. cut them and tied em together and voila problem solved. somewhere in this connector the pins got messed up somehow. you can see in the photo there is a bulge only around the orange/lt blue pin. I couldn't even pry the connector apart so just going to solder them.
 

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now you know why the fuse blew, and the connector melted

too much current.

what did you do?

some high current pump?
 

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Discussion Starter #8
now you know why the fuse blew, and the connector melted

too much current.

what did you do?

some high current pump?
that's the weird part.

the fusible link was actually still good. just replaced it anyways. and the pump is just a drop in HPF 340lph. they pull max like 15-20 amps. have no idea how the connector got melted or damaged.
 

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no idea?

you are going to have a fire!!!!, if you insist in running that type of current through the stock wiring.

that melted connector was just a warning shot, and you are lucky.

the stock wiring is on the cusp of 20amps at 12 volts, and 15' length....

borrowed time.
 

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Discussion Starter #10
no idea?

you are going to have a fire!!!!, if you insist in running that type of current through the stock wiring.

that melted connector was just a warning shot, and you are lucky.

the stock wiring is on the cusp of 20amps at 12 volts, and 15' length....

borrowed time.
my pump only draws 11.8 amps.

14 gauge wiring can't handle that?

Quantum 340LPH E85 Compatible Intank Fuel Pump Ford Mustang GT 5.0/4.6 1986 - 1997, Aeromotive 11140, Quantum QFS-340FT, AEM 50-1205


if not then ill upgrade it to 12 gauge.
 

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you told me 15-20 amps?

no?

11-12 amps no problem

you better go OVER all your connections, that melted one is not a good sign.

if you have a clamp meter, I would check to verify what the actual draw is.
 

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Discussion Starter #12
you told me 15-20 amps?

no?

11-12 amps no problem

you better go OVER all your connections, that melted one is not a good sign.

if you have a clamp meter, I would check to verify what the actual draw is.
yeah sorry about that got confused with another pump.

ill check with an amp meter
 
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