Fuel pump relay problem.

[thepurplepulsar]

The fuel pump doesnt seem to be getting power as it doesn't prime. While poking the relay with a test light, I managed to get the pump to prime and constantly run by bastically earthing the green wire.

The relay has 4 wires, a red wire (coil), green (ecu loom?), red (fuel pump), pink (loom).

The car started, after removing the test light (earthing green) the pump stopped.

Any suggestions on what the problem is..
Stuffed relay?
Something to do with the LT8 and green wire?
Or an earth along the lines somewhere?

Thanks in advance.

[dexi_styles]

E just had a chat with me about it the other day actually.

So ill post it here

Hope it helps ya mate.

Dex

Word of warning tho, pay close attention to wiring up the fuel pump setup.
You can use the existing car wiring and relay but the stock ECU pulls the relay in on the +ive side and the other side of the relay goes to ground.
Microtech (and just about every other ECU maker) pull the relay in from the negative side so you need to make sure you alter the existing earth of the relay pullin coil (Black) to see switched 12v+ive.

Just connect the existing earth wire (Black) across to the Black/White wire on the same relay. Its a fused and switched power supply.

The existing pullin wire from the relay (Green/Blue) will connect to the GREEN wire on the Microtech.

To test it, jusg switch on ignition and touch the Blue/Yellow wire to earth somewhere.
If all is well the pump will run. Worse case, youll pop a fuse!!
Fix that then join the green Microtech wire to the Blue/Yellow stock wire and your in business.

For some reason, if the Microtech Green wire grounds via the relay coil the pump timer circuitry fries and the pump will not be controlled by the ecu.
Its pretty exxie to get Microtech to repair it as well not to mention about 2 weeks off the road.

This way theres no need to fit extra relays or run extra wiring from the Microtech out to the stock relay.

You then just need to decide how much of the original wiring to use or whether to run and entirely new loom out with all new plugs and so-on.

The latter is my personal choice. Im not a great fan of piggy-backing into the stock EFI looms..just me tho.
This will lengthen the installation by a mile but in the long term is a worthwhile investment in time and some extra money for some new plugs.

My 2 bobs neway.

L8tr
E

[thepurplepulsar]

E just had a chat with me about it the other day actually.

So ill post it here

Hope it helps ya mate.

Dex

To test it, jusg switch on ignition and touch the Blue/Yellow wire to earth somewhere.
If all is well the pump will run. Worse case, youll pop a fuse!!
Fix that then join the green Microtech wire to the Blue/Yellow stock wire and your in business.

For some reason, if the Microtech Green wire grounds via the relay coil the pump timer circuitry fries and the pump will not be controlled by the ecu.
Its pretty exxie to get Microtech to repair it as well not to mention about 2 weeks off the road.


L8tr
E

So yeah basically what I tired earlier with the test light, is what bold section of text suggests. I tested it again just then and yeah the fuel pump does constantly run while earthed.

Which kind of narrows it down to the ECU and green wire, unfortunately. The ECU lights still flash as per normal, solid green, flash orange. Doesn't show any red error light.

E, do you know any way of confirming it's the pump timer circuitry. Or is the testing I've already done confirmation in itself?

[tassuperkart]

Im not totally clear on what way youve wired it M8.

However, the Microtech pulls to earth via that green wire.

If you have done the little chageover with the relays existing earth and applied switched 12v to that and it tests out all ok but the pump still wont run when you connect the green wire the yes, your pump timer ciruitry is rooted.

No real biggie. It wont affect the operation of the ECU apart from the fuel pump pullin.

You may have to just reverse the wiring change to the relay back to dead stock and pull the relay in via a 12v source from the key.

In this case, the fuel pump will run all the time when the key is in the run position, motor going or not. Not ideal in the case of an accident but...welll.....shit happens!

Itll cost you around 100 bucks to get it fixed. Your call.

L8tr
E

[thepurplepulsar]

Cheers Evan.

For the sake of $100 I'll do it properly and get the ECU fixed, I don't like the idea of having the pump run constantly. Sound's like a reciepe for disaster.

[tassuperkart]

In the case of "pushing coming to shoving" IMHO thats a wise choice M8.

L8tr
E