I'm using the stock fuel pump wiring to trigger two different relays for my two fuel pumps. The first relay is a normal relay and the second relay is a Beuler time delay relay (it's a BU-508TD model which has since been replaced by the BU-509TD, but they function the same). My issue is that the time delay function on the second relay is not working, and the relay is instead just functioning as a normal relay.



The whole point of the time delay relay is to prevent fuel pump #2 from coming on and off rapidly, as I have a hobbs switch that'll recognize when the car is in boost and ground out pin 85 on the second relay. For simplicity, I didn't include that in the diagram because I currently have the hobbs switch removed from the circuit and am still having the issue of the time delay relay not working as intended. For reference, the second relay isn't wired up to be on all the time as it'd be unnecessarily heating up the fuel instead of just coming on when that extra volume of fuel is needed (under boost).

When I bench test the time delay relay it works as intended (staying energized for up to 3 minutes) after disconnecting power from pin 86. I've confirmed that on the time delay relay pin 30 has constant power, pin 85 has constant ground, and pin 86 is receiving a 12-volt signal when the fuel pump is energized. If I keep pins 85, 87, and 30 wired up, remove the wire going to pin 86 (where the green arrow is on the picture) and instead just jump a wire directly from the battery to pin 86 for a brief second, the time delay relay will function as intended and keep the second fuel pump running for up to 3 minutes (with the 12v wire going to pin 86 removed).

I'm at a loss why it works when I use a wire to put 12v directly to pin 86 on the time delay relay, but the 12v coming through my wiring in the car just makes it work like a normal relay.

I apologize in advance if the diagram isn't the best, this is my first time trying to use software to make one. Any help would be much appreciated.

 

I may be off but, Could it be because the wiring from the car is still "signaled"? In other words, that way functioning as a on/off, whereas when you apply the power from the battery, it is constant, and the delay needs constant rather than signaled power to function properly?

 

You gotta add a diode in so you dont discharge the coil.

 

Also need to add your switch to pin 86

 

I think pin 86 needs the on/off, because when I applied 12v straight from the battery I was just briefly touching the 12v source to pin 86 and after removing it, the relay would still stay energized for a minute or whatever I set the time delay relay to

Thanks for the heads up, I was wondering if adding a zener diode would be necessary but I guess a normal diode would have the same function. I was watching this video ( ) and it seems like they updated the new version of the relay to have a diode built into it.

That's interesting that the switch has to be on pin 86, is that just the nature of this specific relay? Appreciate the feedback, I'll add a diode and change the switch to pin 86 & report back.

 

Try the switch first.
If you get the same result add the diode.

 

Sounds good, will do.

 

For future reference in case anyone comes across this thread, I ended up putting in a 15 amp diode before pin 86 on the delay relay and that solved my issue of the time delay function not working.



I then hooked back up the hobbs switch (keeping it on pin 85 of the delay relay) and it does work that way being a ground trigger. I used the test outputs function on Hondata to keep the fuel pump on, and only fuel pump #1 is running until I pressurize the cold side (the hobbs switch is adjusted to 3 psi) and then fuel pump #2 comes on. When I bleed off the pressure and it goes below 3 psi then fuel pump #2 turns off with fuel pump #1 still running

 

No credit/ shoutout to me?
Damn this place is cold blooded.

 

Ya know, if you do a solid for somebody, just roll with it. If you're expecting props you just come off as grandiose..

 

“Its about respect to some people thats more important” (looks at mia)

 

I got ya. Most of the active regulars have helped somebody in some way, many times over in some instances. Sometimes we'll get a nod, others not so much. I'm just happy to help when I can regardless of the spotlight.

 

Sorry Pepe14, wasn't trying to not give you credit, like I said above I appreciate the help

I guess I just figured it'd be clear to anyone else who comes across this that your suggestions are what led to me solving this issue. No disrespect intended.

 

Lol im just joking around guys