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Fuel pump not running after I shorted out nc contacts in fuel pump relay

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j72x1

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Hello all
Car is Nissan model micra k11 year 1999 1.3 litre mileage 72 thousand miles. Car has been standing over 2 years.The engine turns over okay.I shorted out the fuel pump relay to facilitate draining the stale petrol from the petrol tank.Battery terminal voltage is 13 volts and slightly less at the fuel pump connector with the ignition switched on.Have I done serious damage, how might I get the fuel pump running again ? Thanks for any help, remedies or suggestions Terry
 
Using a multimeter or test bulb check for power at the fuel pump connector with the relay bridged.

If you've power and a decent earth at the connector then the pumps probably failed.
 
Hello Andy yes fuses are okay.with ignition on there is just under 13 volts at the fuel pump connector.
 
If the fuel pump normally operates intermittently and you were running it continuously for a prolonged period its coil may have burnt out? An Ohmmeter test of the disconnected pump coil should indicate its state.
 
Hello Alec
Let me give you the full picture.car has been standing over 2 years.i connected a battery turned on ignition and the fuel pump worked fine
I then shorted nc contacts 85. 86. of the fuel pump relay to drain old petrol from tank.the fuel pump did not run and has not run since.there is about 12 volts at the fuel pump connector, pump resistance is 9 ohms.the. fuel pump is not shortng to earth.thats about it really. Terry
 
If you shorted out NC contacts on a relay you would achieve nothing as they are already able to conduct. I would have thought the pump should be connected via NO contacts if it is powered by a relay.
 
Hello jj.i shorted out nc contacts as I thought it would be safer.is it not dangerous to short out no contacts? Terry
 
Oh no - Did you really short pins 85 and 86 together?

Do you know how a relay works?

I hope pin 86 wasn’t connected to the ecu, otherwise you might have blown the computer.

Your explanation is dire. Are you trying to run the car without fuel and then ruling out a problem?

Ensure there is enough fuel, and try starting the car. Does it crank? If so, do you hear the fuel pump/relay engaging?
 
Actually I may not know how a relay works.i don't know why you think I was trying to run the car without fuel.i was trying to drain the stale petrol from the petrol tank.i hoped bridging the nc contacts would allow the fuel pump to run continuously,and so drain the petrol tank.
The above makes sense to me what you wrote has confused me.read this message and see if you can help me.if you need further info just let me know. Terry
 
Contacts 85/86 would normally be the relay coil terminals. Shorting those ought to blow the fuel pump fuse. I'm surprised you still get ~12V at the pump.
 
j72x1 said:
.i shorted out nc contacts
Click to expand...
The K11 fuel pump relay doesn't have any NC contacts - it's 2 connections for the coil and 2 for the NO contacts.

Alec_t said:
Contacts 85/86 would normally be the relay coil terminals.
Click to expand...
They are, and one of them is connected to +12V and the other one to the ECU, the relay being activated by that ECU pin going to ground.
Shorting them out would have applied the full 12V to that ECU pin with basically unlimited current. If lucky it's just blown a fuse. If not then it's damaged the ECU.

Edit: The +12V for that relay comes from a 15A fuse, so if that was connected direct to the ECU pin it's very likely the ECU has been destroyed.
 
Thanks flameport for that ts likely I have destroyed the ecu.it seems I can be very stupid when I don't know what I am doing.the 15 amp fuse you mention,that would be in the fuse box by drivers right leg?
If that has not blown then the ecu is buggered.is there any way i can confirm it needs replacing?
This has been a very important message for me.please respond to it, and let me know the worst.Thank you Terry
 
You said you had 12v at the pump on one pin of the connector. If it is a 2 pin connector were you measuring across it to detrmine you had 12v or from one pin to another earth point. If you were measuring across it then the pump should have been running and must be faulty. If it was to a seperate earth then connect the other pin pf the connector to earth and the pump should run so you can drain the fuel.
You then need to measure across the connector while turning the engine over to see if the voltage rises from 0 to 12v. If it doesn't then that suggests the ECU is perhaps faulty.
 
The pump is a 2 pin connector.i connected a multimeter earth to earth and positive to positive, so the pump must be faulty?
From comments by other members it's likely I have destroyed the ecu
I am confused about the following.this morning I connected a 12 volt voltage from the cigar lighter to the fuel pump connector.i know the resistance of the fuel pump is 9 ohms and it is not shorting to earth.why did the pump not run under these conditions? Terry
 
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