Mercury ECU Replacement (824003a8)

[bradleypeay]

I am about to send my ecu off to simon motor sports to be rebuilt (fuel pump driver failed). What should I check before reinstalling? I don't know what caused it to fail (possibly low battery voltage??? Battery died just before failure) and don't want to damage the new one. Tia. Brad

[wired247]

You can...

A. Save your money and don't send it in to get the ECU's fuel pump relay fixed. You can wire in auxiliary relay to turn on when the ignition switch turns on ( DO NOT RUN THE PUMP DIRECTLY OFF THE IGNITION SWITCH CIRCUIT ) to power the fuel pump circuit. $10 worth of parts and you won't know the difference. You can do the VST delete bit and set it up like a hipo motor with external pump and regulator for around $200 or just use the original VST pump set.

B. Have the ECU rebuilt. It is common in control circuits to take the main current loading off the control computers relay set by doing essentially what you did in A. but instead use the wiring that powered the fuel pump to power an auxiliary relay that in turn powers the pump. Its a LOT lot easier to change an auxiliary relay located outside the ECU than it is to change the ECU's built in relay and the vastly reduced current draw from the auxiliary relay compared to the pumps current draw will keep the ECU working like it should for a long time.

C. Spend the extra few hundred bucks and buy a Brucatto ACU and never look back.