Wiring questions

[SHutson]

I'm redoing the wiring on my car and have a few questions. It came to me with no fuses anywhere in the wiring. It seems to me that at least some of the circuits should be fused.

My fuel system is an electric pump from the cell to a swirl pot and the carb is fed with the standard mechanical pump from there. The last car I built (BMW vintage) was fully fused and, in particular, had both a fuel pump fuse & safety relay triggered by an oil pressure hobbs switch. That relay design may have come from the SVRA rulebook. Thoughts on using a similar system on my S2000? Overkill?

What about an impact switch in the fuel pump wiring (or even the ignition/fuel pump switch circuit). Are most of you running one?

Safety first, but would I be adding too much complexity (and potential failure points) to the wiring system?

[JHerscher]

I run a mechanical fuel pump but as I understand it you must have a g-activated or oil pressure switch of some sort for an electric fuel pump. Make sure you can reset it from the cockpit.

I’ve never run a single fuse on a race car.

there will likely be other opinions…

[David Ferguson]

Most Sports 2000 used mechanical fuel pumps, so to the wiring was very simple (Master Switch, Ignition Switch, Brake Switch, Rain Light). if you want to protect the fuel pump wiring, then I suggest you use a circuit breaker, like one of these:

https://prowireusa.com/c-24-klixon-2tc-series.html

Safety relay is probably a good idea as you would want a relay anyway for the fuel pump.

[Rick Kirchner]

I've run electric pumps for years, was unaware of any rule for a g-switch or OP switch (an OP switch then requires a start bypass). Kinda thought all of that was what the master switch was for. I have a slap cover for my single switch that turns everything on except the dash. Also, since the dash is the canary in a coal mine, its sudden absence tells me I have some kind of a voltage problem. Wire your car with mil-spec teflon wire and at least when you cut the power the wiring will self-extinguish, unlike some other insulation formulations.

IMHO, fuses are a designed-in failure point. Those little elements are subject to vibration, so if you use them, I'd use the blade variety in a vibration isolated box. You have room in a S2.....

I think a much better solution than fuses are klixon mil-spec circuit breakers. The only fused circuit I have is for the rain light, and the klixon serves as the on/off switch as well.

Also if you have the room, routing the harness such that a harness fire doesn't spread to other things is a real good idea.

Dave beat me to it!

[Jerry Kehoe]

As my car has an electric pump filling the make up can before it feeding a Hilborn pump on my FI , for safety sake I installed an impact switch in case of an accident. The electric pump has a toggle switch so this eliminates fuel pouring out all over if I can't switch it in an accident. Simple, easy and safe.