Boost a Pump Install

[flinguist]

Want to install a boost a pump. After looking at fuel pump rewire vfaq http://www.raktron.com/fuel/denso1.html, the relay wiring conflicts a bit with the MSD Boost a pump instructions, which use the same relay.
Looks to me like the power wire from the fuel pump would go to 85 and ground to 86, which is the opposite of the rewire vfaq. What do you think?

You must be logged in to view this image or video.

 

[dustyboner]

as long as the relay or the relay plug has no diode, polarity on the activation coil doesn't matter. I checked the datasheet for the relay (assuming iMSD is still using a P&B VF4-85F11 relay) and there isn't a diode.
check the plug for a diode. sometime they have black heatshrink on them and are easy to miss.

the relay will usually have a diagram on it. if you look at this one, it has the diode symbol at the bottom. The diode is connected with reverse polarity to the power supply. So on the pictured relay, you would have to connect 85 to ground and 86 to (+)

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[flinguist]

Looked at the relay schematic. Just a coil, no diode. Thanks

 

[flinguist]

Looked at the relay schematic. Just a coil, no diode. Thanks

Install went well. Put it under the drivers seat. 17 volts while idling, 20.5 volts at 25 psig.