Fuel pump primary circuit malfunction?

**a3aud11** · 25-05-2012,02:05 PM

Have fault code coming up.
Fuel pump primary circuit malfunction.
If anyone can help, would be much apprichiated.

**jonathanfenton** · 28-05-2012,12:00 AM

sounds like a faulty fuel pump! ;-)

**a3aud11** · 28-05-2012,05:11 PM

Upon further finding. I have jumped the circuit using a wire bridging the connections on the fuel relay, when I do that the fuel pump fires up and works. If the fuel pump was faulty would it still be priming and working?

**zollaf** · 28-05-2012,05:31 PM

sounds like a faulty relay.

**jonathanfenton** · 28-05-2012,06:21 PM

If you've bypassed the relay and it works then sounds like relay. Put your meter in relay trigger trigger port and other end on earth if it goes live when you turn to 3rd ignition then obviously it's the relay if that stays dead then you have bigger problems. Where did you get the power from to bypass the relay? A 12v feed ie battery or from the relay supply live? Obviously the supply live will be live but rely on the trigger live from ecu to activate the relay. Goes without saying to not supply the pump from the trigger live as you will melt things.

**a3aud11** · 28-05-2012,06:36 PM

Thanks for all your your quick responses. I will out a meter on that and get back to you on that.
I thought it was the fuel pump relay so replaced it but the problem was still there. Is there more than one relay that works the fuel pump?

I got the power from the battery
hope that helps?

**jonathanfenton** · 28-05-2012,07:06 PM

No idea sorry just using generic knowledge on relays. Does it click when you turn key to position 3? (sometimes if very quiet put your thumb or finger and fire it up. Also check you dont have a immobilizer problem as the ECU could be blocking it from working.

This is how i would test it.

Relay should have 4 prongs.

Positive Signal (from ecu) +
Positive Feed (from batt) +

Negative Signal -
Positive feed (to pump) +
I would put my meter on the signal positive and negative on a known earth like bare metal or on car batt neg. turn key to 3rd position and you should see 12v
If that works try it on the relays negative signal prong if that works then continue. if not then trace negative feed and see where it comes from and fix could be a faulty earth wire.

If you get a flow from signal plus and neg then move onto the supply plus (from battery) Check that the supply plus is live by checking from the port to the battery neg obviously should see +12.

If you get to this stage you have proven the relay circuitry from ecu and battery and problem lies between the relay and the pump. I think the fuse should be in the engine bay in the 2nd fuse box. It should then go to the relay socket then to your pump.

You mention that you gave the pump a positive feed from the battery... did you put this onto the relays positive port or just run a cable to the pumps positive terminal? Try running a positive feed to the relay port that goes to the pumps positive terminal.

Hope this makes sense!... Can draw a picture if it makes it easier to understand?

**jonathanfenton** · 28-05-2012,07:29 PM

additionally check fuse FC 27
4th row down,
6th across (15a) depends on if this diagram is from a left or right hand drive... think they are backwards... this is in the car fusebox... think its drivers side under side panel.

**a3aud11** · 28-05-2012,08:16 PM

Lots of information there. Thanks. Very helpfull and definitly worth a try.
If you could draw a picture as well that would be much apprichiated!
Will try this and check the fuse and let you know the outcome. Thanks once again.

**jonathanfenton** · 28-05-2012,10:16 PM

The fuse gauge sender is different from the gauge its self... it will just send the signal to the ecu to let it know how much fuel is in. The ECU will then tell the display what to display. Would expect this to flag a fault if this had blown.