Mi16 Fuel Pump Relay Not Working

[Veero 1]

Right I have just built a new Mi16 loom. I have been extremely careful, measured 3-4 times cut once type affair. Anyway it is now in the car and ready to go. However I am getting no feedback across the fuel pump relay, as such the fuel pump is not working and therefore the engine will not run. It turns on the starter but nothing much happens apart from running my battery down.

 

Basically the injector relay clicks as it should but the fuel pump relay remains inert. There is 12v across the switching pair of pins on the relay base but it is clear the relay is not being switched to earth by the ECU. If I bridge a jumper lead from the earth pin of the switching pair on the FP relay I can hear the fuel pump spinning, but doing it with the key in the ignition on second click it does nothing. As far as I can tell the switched live goes to the base of the switched pair on the FP relay, this is then grounded through the ECU by earthing pin 03 (it's a 3 row loom), however for some reason it is not.

 

I have continuity tested the whole loom at length and all the ECU pins are going to where they should. Switched and permanent lives seem to be giving what values they should. Earths seem to be good, one large one to gearbox and another to a spade which has a good chassis earth in the cabin.

 

When I start the diagnostics test it just gives the code for end of test, so no apparent ECU errors are there.

 

I am on the verge of going mental, I have been over every single thing I can think of, tomorrow with any luck I may be able to try my ECU in another Mi16'd 205 and their ECU in mine if things go to plan.

 

Please help or suggest anything if you can, its been a long week building this thing, redoing the engine bay sensor loom and fitting it all to the car. I am near giving up with this damn thing.

 

Cheers

Veero

[welshpug 1,657]

are you getting spark?

[Veero 1]

Not 100% sure. Figured since I know the FP isn't getting power then it won't run anyways. There is definitely 12v switched live to the appropriate coil pin. SUggestions on how to test? I don't have a spare sprk plug I can use on the king HT lead.

[welshpug 1,657]

just stick something metal in the end of it and put it to earth.

[Veero 1]

Tried that before I remembered not plugging in the permanent live and it didn't work.

 

I'll try it tomorrow but if that fails what would be a good port of call? Could the not sparking cause the ECU to not make the fuel pump relay switch?

[welshpug 1,657]

TDC sensor

[Anthony 1,003]

As above - check for spark, and if you haven't got one, try another crank sensor. The fuel pump only runs when the ECU senses the engine is turning, which it won't do with a failed crank sensor.

[Veero 1]

OK will try that tomorrow. I'm dead certain it's all plugged in right. Nothing to suggest before I rebuilt the loom that the TDC sensor was kapput, infact I think it was relatively low miles, certainly I got it brand new from Citroen a couple years ago.

 

I connected the 3rd pin on the TDC sensor to the earth shield on the cable for it, should I have done? I got the impression from a wiring diagram that the earth screen for the cable went to the 3rd pin on the sensor.

[Veero 1]

But the fuel pump always used to prime before the engine was running. Now it doesn't even prime.

 

Plus there's definitely no spark, trying to rectify it now...

[Veero 1]

All sorted, had 2 pins mixed up on the TDC sensor. oh and the ICV plugged into the temp sender and vice versa.

 

Now all I need to do is fix the trim back on and get it rolling tomorrow.

 

It ran surprisingly well for being sat for 4 months.

[Chris_Mi 6]

Veero,

 

Before you close this thread, can you tell me which the IDV and temp sensor are. I've had this problem intermittently on my Mi for some time now.

 

Cheers

Chris

[Veero 1]

What do you mean which they are?

 

ICV is the small cylindrical thing with pipes that bypass the throttle and the temp sender is the blue two pin fitting on the side of the thermostat housing.

[Chris_Mi 6]

Still learning! Thanks