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Fuel Pump Dramas! Need Help!

chef_stagea
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chef_stagea Grand Master

chef_stagea

Posted
Posted

ok so i put my walbro pump in today fitted strait up to my stock set up pretty much... plug and all!!! :blink:

then i attempted to do this 13.8 volts thing... bassicly

got a relay... had 4 terminals... 2 input and 2 out put...

2 inputs were 12v (dirtect battery feed...) and a ground...

with the out put... i cut the positive and put the 2 ends on the pos and neg.... and grounded the negaitve to the body...

i managed to get 12.5 or there abouts... did i do this wrong? any one who has ACTUALY done it got an answer for me??

it did drive like this but then it cut out n went all shit... had to take it back to stock wiring in the carpark of the local pub lol...

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Duncan Grand Master

Duncan

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Posted

well....you are checking voltage with the motor running right? 12vish is right for battery alone, alternator should show 13.5+

the wire you ran from the battery to the relay has 13.x at the relay end when the motor is running?

pins on the relay should be:

30 - wire to the battery (fuse near the battery)

85 - earth

86 - original fuel pump positive (signal)

87 - output to the fuel pump.

you should get the same voltage at pin 87 as the battery when the ignition is on.

QWK32 Veteran

QWK32

Posted
Posted

have a look on the bottom of the relay, each of the pins will have a number stamped beside it. it should be the same number on all automotive relays, so hook up the wires to the pins Duncan said and it will work.

basically explained, pins 85 & 86 switch the relay which joins pin 30 to pin 87. so when the original setup tries to turn the pump on, you use the original positive feed to the pump and any ground to switch the relays coil, which connects the new 12v feed from the battery to the new fuel pump.

chef_stagea Grand Master

chef_stagea

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  • Author
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have a look on the bottom of the relay, each of the pins will have a number stamped beside it. it should be the same number on all automotive relays, so hook up the wires to the pins Duncan said and it will work.

basically explained, pins 85 & 86 switch the relay which joins pin 30 to pin 87. so when the original setup tries to turn the pump on, you use the original positive feed to the pump and any ground to switch the relays coil, which connects the new 12v feed from the battery to the new fuel pump.

ahhh thanx so so much!! I'll get onto it!! ;)

QWK32 Veteran

QWK32

Posted
Posted

going off those pics, if you hold the relay the same way as in the pic this should work,

post-34711-1275003641_thumb.jpg

it also doesn't look like an automotive relay, but should still do the same job, just make sure you insulate the terminals so they don't short out on anything. if you want a proper automotive relay go to supercheap, they aren't expensive to buy.

pipster11 Grand Master

pipster11

Posted
Posted

its like that 3rd pic

the 12v on the left is from the ecu

the 12v on the right is from the battery

the ground goes to the chassis (make sure its a good contact, i.e. no paint in the way)

chef_stagea Grand Master

chef_stagea

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darren yes i have read that... and thats when i originally did but it did not work :) ill try the ways mentioned and see what happened... then im unplugging the pump and getting the volt reading from there correct?

chef_stagea Grand Master

chef_stagea

Posted
  • Author
Posted (edited)
going off those pics, if you hold the relay the same way as in the pic this should work,

post-34711-1275003641_thumb.jpg

it also doesn't look like an automotive relay, but should still do the same job, just make sure you insulate the terminals so they don't short out on anything. if you want a proper automotive relay go to supercheap, they aren't expensive to buy.

so i tryed this one and its getting power all the time now... do i stick with this and wire the battery lead into the acc.... or... have i stuffed it up once again...?

so ive played a little more... it only comes on with this set up when i turn the key... once its on pulling the fuse nere steering wheen doesnt stop it... and it doesnt no when to turn off?

Edited by chef_stagea
chef_stagea Grand Master

chef_stagea

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  • Author
Posted (edited)

i went out and swapped my relay over.... got a proper automotive one... same problem.. turns on with ignition... runs at like 14.2 v then once you turn the key off... it turns the fuel pump off for a few seconds then keeps pumping and just flows threw the engin and back to the tank....and has to have the power cut from it momenteraly to stop it...

Edited by chef_stagea
chef_stagea Grand Master

chef_stagea

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on my relay...

pin 30 is my new 12v lead from battery...

pin 85 is earthed

pin 87 goes to the fuel pump (positive)

and pin 86 is the car end of the old positive lead...??

i did read somewhere about r33s having the negative wire on the fuel pump (untouched at this stage) grounded? i cant see this doing anything?

QWK32 Veteran

QWK32

Posted
Posted (edited)

the reasoning behind grounding the old pumps negative is because there is a capacitor rigged up in the old pump setup, its there to help with power surges and general smoother running of the stock pump. because you are using the original pumps feed to switch a very low current drawing part (relay) it could be taking a while to dissipate the capacitors charge, hence the relay is staying pulled in. ground out that negative and see if that solves your problem.

ps. that last diagram you posted is what you said you have done anyway :)

Edited by QWK32
Duncan Grand Master

Duncan

Posted
Posted

ahh OK I may have been wrong about pin 86 and 85.

Check if you keep positive voltage at the old positive feed more than 10 seconds after the ignition is turned on. Same check for the original earth - does it have continuity to earth more than 10 seconds after the pump is turned on.

If the positive drops out, old positive to 86 and 85 to earth

If the negative drops out, old positive to 86 and old negative to 85.

That should do the trick either way - as Josh said it might be earth triggered

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