MoTeC Global Forum

Hi,
I have a single Walbro 525 pump (max amp draw 25A) running continuously, with a second stage of two more Walbro 525s that will kick in above a certain boost level.
Worst case scenario, I will have a 75A draw across the three fuel pumps for no more than 7 or 8 seconds at a time.
How should I configure this within a PDM, given the individual 20A load ratings of each pin?
Thanks
Craig

Hi,

Does the pump actually draw that? You could group two 20A outputs or three 8A outputs with the same control strategy to cover the current draw of the pumps. Otherwise, if there is only a short period that the current exceeds the limit and then drops below the output limit you could run them off the single 20A outputs.

max current draw will depend on pressure.

As a bit of a comparison, running 3 x 450's on mine for a test ( engine not running ), at I'm near sure I had base pressure around 56psi, they pulled 45A with about a 90A peak spike startup current

Normally I PWM the pumps via a SSR, just ran them all at 100% duty for a test.

Never did test them at say 85-90psi to simulate with boost though.

But I'd say it would be quite plausible for the bigger pump to be 25A each if run at a high pressure