Flex-A-Lite fan wire problem

[silk240]

ok, i have a s13 coupe with a blacktop sr20det, i had my fans wired up so that whenever the key was in the "on" position the fans would run constantly, with or without the engine actually on. so know i have run a switch so that i can turn the fans on and off. the problem i am having is when the switch is "on" after the engine and fans cut off, the switch is still drawing power. how can i set it up so that the switch cuts off too when the engine and fans do? please help

[r3v_v3ng3]

wire it up with the fuel pump fuse

[silk240]

that wont overload that circuit and cause a blow out of the fuse or other fuses?

[DarkknessD]

wire it up with the fuel pump fuse

Nope, it shouldnt.

[krazydriver]

Well if you powered the fan directly from the fuel pump relay... yes it would cause issues.

I think what he is suggesting is to use the fuel pump relay, to trigger the actual fan relay. This way the fan will not turn on unless the fuel pump (and engine) are running.

[silk240]

whats the process of tapping into the fuel pump rely?

[krazydriver]

Here's what i would do.

Factory fan relay gets the actual power from battery, trigger power is constantly there and the ECU controls the ground. (obviously the other wire powers the fan.

So all we're doing is switching the ground to a constant ground, and the power trigger for the relay is spliced in from the wire to the fuel pump, which will then turn on the fan when the engine is running. Relays draw hardly any current so there's no need to worry about anything setting it up like that.

Just test which of the pins off the bottom of the relays are power, and then just cut and splice.

Other benefit of this way is everything is still a separate circuit, if the fan fuse blows it's the fan, if the pump fuse blows it's the pump.

[silk240]

but the fans will be constantly running, correct? with no way to manuel turn them on or off. is it ok for the fans to constantly run, dont want to burn out the fan motors?

[krazydriver]

Well if you want just run the ground wire from the fan relay into the passenger compartment, put a switch in it, then ground it to any ground point inside.

This way the fans will only get power to run while the fuel pump/engine is running and you'll be able to switch the fan on or off as you deem necessary.

On the other hand i ran my KA AC fan as a cooling fan... always on for over 6 months with no problems.

[ca18detgabby]

why not just re-wire to the Key on you had before....... and add the switch inline?

stead of messing with the FP

[silk240]

^^ because i dont want to sit in my car while my turbo timer runs ans wait so i can turn the switch off. because if i leave the switch in the on position it draws power from the battery.

[ca18detgabby]

^^ because i dont want to sit in my car while my turbo timer runs ans wait so i can turn the switch off. because if i leave the switch in the on position it draws power from the battery.

yeah so re-wire it back to Key ON setup, and then splice in a switch on the grounded side and run that back into your interior. little extra wire is required but is very straight forward.

[silk240]

yeah i figured it out now. i put the switch on the power wire that ran from the rely to the fan, so now it runs rely to the switch, the switch to the fans. with a ground wire from the switch to a ground. then the other power wire running from the rely to the battery. soon as the engine is cuts off the fan and switch cut off as well

[silk240]

Thanks for everybody's help!

[MasterOfAngle]

I thought about wiring my flex a lite fans to my fuel pump relay but I decided to keep it thermostatically controlled since its actually better for your engine. Ive used this setup for 2 years and my battery hasnt died before even when the fans are running for 30+ minutes on a hot 95 degree summer day. But im running a 900 amp battery.

[silk240]

yeah my battery sucks, i am running a smaller battery, a miata batt., than i probably should because my cold pipe is in the way if i use a full size battery and i have not bought a battery relocation kit.