I installed the Mallory 685 on the car and ran the window switch wire to the nitrous relay for the solenoids. the problem I'm having is when it gets to desired rpm to turn the nitrous on it pulsates the relay. If you take the wire off the relay it doesn't pulsate but as soon as its connected to the relay it starts pulsating again. if i remove the wire and run that leg of the relay straight to ground the n20 works perfect. wtf is the problem???

 

relay fucked?

 

I tried a new one from my brother in laws n20 set up and still the same result

 

it doesnt do this with the wire simply grounded? check the connection between the 2 and the mallory ground

 

take it back or send it back i orderd one and it was fine for 2-3months then it took a $h1t.the samething happened to my brother he orderd 1 also and he installed it and it was a piece of crap also he took it back and got a new 1.
these where brand new in the box they have tons of defaults the 685
and that has happened twice on both his cars 95z and 78nova
send it back
good luck........

 

The window switch wire is a ground according to page 11 of the manual. The 685 is rated at 10 amperes maximum for this. You should create a special grounding circuit with larger gauge wiring with another relay. In other words, you use the ground circuit created by the Hyfire to active another ground circuit; that is what I did. The ground created through the Hyfire's violet wire can't allow for much current. It looks to be a 20-22 gauge. My circuit activated by the window is 14 gauge and can handle 30 amp solenoids.

I too had pulsing but it was because of my fuel pressure safety switch. I have a wet kit on my LT1. The fuel pump did not deliver enough volume to keep the pressure switch from pulsing on and off. I have since then added an inline booster pump.

 

do you have a diagram on how you ran yours. I tried calling mallory for help but they are closed until august the 3rd for inventory.

 

if it is a factor of the 685 not being able to handle the current, you can use a relay to supply a dedicated ground and the 685 to activate the relay

685 to pin 85
12v to 86
chassis ground to pin 30
solenoid ground to pin 87

this uses the 685 to trigger the relay and the solenoids will have a direct chassis ground

This should not be needed tho'