Substitute 'Black' relay for a 'RED' Fuel pump relay? Car running like normal 911...

[Tilikum Turbo]

I have been having issues since installing an open wastegate pipe on my car.

1 week after installation, I now only have boost until about 4500-5000 RPM...and then power drops off in all gears.

Otherwise, the car runs/idles normal.

I have no boost gage(installed 86 930 'stock' engine in a 911SC), so I can't see if I have actual full boost/partial boost.

I checked my fuel pump relays, and found 1 bad(I installed it in the HORN relay recepticle, and the horn didd't work...when I put in the other fuel relay, the horn worked).

Then I took a black/spare relay and placed it in the 'original' spot, but the car still runs with no gusto.


Are the black/red relays compatable?

Any other idea's why the car might run normal, until 4500-5000 rpm? Car is very well maintained, clogged fuel filter maybe?

Can out of the two fuel pumps, 1 actually 'sound' likes it's working, but not?

thanks for any and all help!

[mark houghton]

Go to this link and read the two pages on "stoopid relays". Several members do a great job of explaining red vs. black stoopid relay question

And this pretty much sums it up:

You can use red relays for inductive loads like electric motors (fuel pump) and for resistive loads (lights).
But you cannot use black relays for inductive loads, you only use black relays for resistive loads.

[jimtweet]

red vs black fuel pump relays