Is it true?

skipnrocks · Jul 19, 2013

I have a little ranger race truck and switched to a fuel cell. The fuel pump quit working the first week. I was told it is because I hard wired it and that it needed a relay to work properly. I also have my fan hardwired and was told I needed a relay with that also. I have had many fans hardwired and never had an issue, and was thinking previous fuel pumps I had were also.

So is it true. Do I need a relay for fan and pump for them to work properly? And if so is there some sort of inline relay I can wire in?

RustyC · Jul 19, 2013

Relays are needed because most toggle, rocker or whatever switches can not handle the current (amps) long term. Yes it will work but the contracts in the switches will eventually burn and the switch will not longer work, possible causing damage to the fan or pump due to low voltage.
My advice is to add a relay for the fan and the pump. Both can be turned on by the key switch. Find the wire that has battery voltage with the key on and use it to turn on the relays. Running them off the key switch make it easy to shut them down in the event of a roll over or other emergency.
In simple terms relay are just big switches that are turned on by another switch.

John Galbreath Jr. · Jul 19, 2013

Yes on the fan, I do not on the pump. Did not think they pulled the current to require it.

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crawlin85cj · Jul 19, 2013

The starting amp spike of any electric motor will wear on the contacts in a switch even if it is rated for the full load run amps. It never hurts to use relays on a circuit. Spares are easy to carry and swap in, typically easier than a switch.

skipnrocks · Jul 20, 2013

The harness is a mess, all cut down to eliminate all the extra but not cleaned up enough to try and use factory relays. Sounds like I may need a relay do they make one you can just wire inline?

jeepjeep · Jul 20, 2013

Yep, any parts store will have universal relays up to ~30 amp pretty cheap. I ended up using a 79 ford starter solenoid to run the high side of my Taurus fan because a higher amp relay was $$$.