Technical > Wiring & Sensors

Fuel pump relay staying on when VEMS powered OFF through P259 output

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gunni:
So my fuel pump is running when the ecu is powered off, the main relay also stays on,
I´m using a 3.8 board, when I turn the ECU on the pump operates as per the software, i.e primes and then stops. serial number is 9680.

Not sure if it´s related.
At the same time pulsewidth for lambda 1.0 at idle has gone from 1.37ms to 1.42ms , no change in fuel pressure, not sure if that relates to this issue.

Kamuto:

--- Quote from: gunni on December 05, 2014, 04:45:52 pm ---So my fuel pump is running when the ecu is powered off, the main relay also stays on,
I´m using a 3.8 board, when I turn the ECU on the pump operates as per the software, i.e primes and then stops. serial number is 9680.

Not sure if it´s related.
At the same time pulsewidth for lambda 1.0 at idle has gone from 1.37ms to 1.42ms , no change in fuel pressure, not sure if that relates to this issue.

--- End quote ---
it's the protection diodes inside ecu :) if you  turn off ignition and fuel pump relay is still getting +12 from somewhere it will trigger from these diodes, if you rewire relay that it wont have +12 with ignition off no problem then

gunni:
It's unwanted as i am getting 12v from a different supply then the 12v for the ecu, and I'm using standard wiring so it's not an option at all to have this happen.

fphil:
"I'm using standard wiring" you mean E36 Pin15. You did not invert the logic? so the pump relay should be on when E36Pin15 (not wired) is grounded (0.001V)? This is what I get on the bench, also pin 15 gives a floating 0V (0.08-9) when not running.

I guess that this relay stays on because of a small be sufficient current through the solenoid.  I would try to reduce this leak using a resistance in line.
Of course the value of this leak and the sensibility of the relay are dependable

gunni:
No standard engine wiring, i.e oem loom.

I have and want to use the p259 outputs for relays, and it seems without proection diodes is the only way.

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