Wierd Fuel Pump Relay Problem

colinb444 · Saturday at 21:56

Hello
Looking for someone wiser than me for help.
For the last 3 weeks my 2007 3.6 tdv8 has been running terrible.
Any time I try and put my foot down car would hesitate then go into limp mode
with errors including HTC fault ???.
Over the last 2 years the car has cut out about 3 times and I have had to had to bridge the terminals
for the fuel pump relay to get it going again. Once going I replaced the relay and the car would be fine.
Out of curriosity I bridged the fuel pump relay terminals again and the car has ran spot on since
(keep removing the bridge after every journey to stop any damage to the fuel pump)
I have tried 3 different relays and get the same problems, only when I bridge the terminals
does the car run fine.
Am I just unlucky with buying duff relays (all test fine) or is there something else going on?

Any help/suggestions would be much appreciated.

Datatek · Sunday at 08:22

colinb444 said:
Hello
Looking for someone wiser than me for help.
For the last 3 weeks my 2007 3.6 tdv8 has been running terrible.
Any time I try and put my foot down car would hesitate then go into limp mode
with errors including HTC fault ???.
Over the last 2 years the car has cut out about 3 times and I have had to had to bridge the terminals
for the fuel pump relay to get it going again. Once going I replaced the relay and the car would be fine.
Out of curriosity I bridged the fuel pump relay terminals again and the car has ran spot on since
(keep removing the bridge after every journey to stop any damage to the fuel pump)
I have tried 3 different relays and get the same problems, only when I bridge the terminals
does the car run fine.
Am I just unlucky with buying duff relays (all test fine) or is there something else going on?

Any help/suggestions would be much appreciated.

Any sign of bluing on the relay contacts? Could just be bad connections but being as these cars are very complex, it's more likely to be the control for the relay is missing. Needs proper diagnostic but someone with more knowledge will be along.

mystery · Sunday at 08:47

I assume you have replaced the fuel filter to eliminate low fuel delivery and checked the relay contacts etc on the dud relay to confirm it is the relay.have you checked for 12volt signal at relay and the ground is good

colinb444 · Sunday at 11:07

mystery said:
I assume you have replaced the fuel filter to eliminate low fuel delivery and checked the relay contacts etc on the dud relay to confirm it is the relay.have you checked for 12volt signal at relay and the ground is good

Hello
Thanks for the info.
Have tried 4 different relays, all test good. Have not replaced the fuel filter yet. If it was a 12v/earth or fuel filter
problem why does it run ok when I bridge the relay.

Mark Piercy · Sunday at 11:11

Maybe an issue with the relay earth and command positive?

Mark Piercy · Sunday at 11:12

colinb444 said:
Hello
Thanks for the info.
Have tried 4 different relays, all test good. Have not replaced the fuel filter yet. If it was a 12v/earth or fuel filter
problem why does it run ok when I bridge the relay.

It'll run as you say because it's given a dedicated power supply by bridging it.

Datatek · Sunday at 14:28

Because the si

colinb444 said:
Hello
Thanks for the info.
Have tried 4 different relays, all test good. Have not replaced the fuel filter yet. If it was a 12v/earth or fuel filter
problem why does it run ok when I bridge the relay.

Because the signal to operate the relay is going AWOL which is why it needs proper diagnostics.

mystery · Sunday at 17:11

try running a ground wire from relay connection (BP) to eliminate the ECU SIGNAL,if this cures the problem then you will have to trace the BP wire back to the ECU.but also check relay connection on fuse box for tight fitment,this can be checked with a male spade connector or it, equivalent type ,you should feel the tension when inserting and removing

colinb444 · Sunday at 18:45

mystery said:
try running a ground wire from relay connection (BP) to eliminate the ECU SIGNAL,if this cures the problem then you will have to trace the BP wire back to the ECU.but also check relay connection on fuse box for tight fitment,this can be checked with a male spade connector or it, equivalent type ,you should feel the tension when inserting and removing

Thanks for that.
I have ordered a new fuel filter (needed it anyway).
Have managed to find wiring diagrams so will look into that ASAP

Regards

Wierd Fuel Pump Relay Problem

colinb444

Member

Datatek

Well-Known Member

mystery

Well-Known Member

colinb444

Member

Mark Piercy

Well fumbled member....

Mark Piercy

Well fumbled member....

Datatek

Well-Known Member

mystery

Well-Known Member

colinb444

Member

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