I am wonderring if it is possible to place some sort of electrical device in line a wire to allow current only to travel one way. My scenerio is this. I have a battery hooked up to a three way switch so positive and negative to the middle prongs on the switch. I have a positive and negative running from one side of the 3 way to a fuel pump and the other side of the 3 way to my tach. I also must wire from the ccu to the fuel pump. This is necessary as the sled does not have enough initial power to get the fuel pump going so I have to turn the 3 way to the power side for the pump start the sled and then switch to the tach side so it shuts off the battery feed for the pump and the now running sled has enough power to power the fuel pump. The problem is because i have power from the pump to the ccu and power to the switch when I switch the switch to turn the pump on for start up it is running back to the ccu. I obviously do not want this to happen and therefore was wondering if a diode or resistor or something could be put in line so only power coming from the ccu could go to the pump but not from the pump back to the ccu. Yikes I hope I explained this ok. Anyone?????

Diode allows the voltage to flow in only 1 direction

A sled's alternator produces AC. Not sure how you are powering a 12V DC electric fuel pump with AC. This can power items such as 12V lights, but not run DC devices such as fuel pumps. A full wave bridge rectifier is used by many to convert the AC to DC to charge a battery and/or run a 12V electric fuel pump. This is available from a dealer or supply house, and is commonly used to charge a battery in an electrically started sled. It simply installs into the yellow lead going to the voltage regulator. I use this device for turbocharged sleds to operate the electric fuel pump, with/without a battery. It must be large enough (25 amps?) to handle the devices installed inline. Maybe you already have this in the system? If so, you can just wire the alternator to charge the battery and connect the electric fuel pump to the battery and use a switch to turn it off/on as needed. The battery then provides a reserve of 12V DC energy for when the sled's AC output is too low.

The F and M Chassis sleds use a DC fuel pump which gets it's power from the ecu, which is converting only that output to DC already, it's the only thing on the sled that is DC (I used this to get power for my Digital Water Temp Gauge)...... as for your question PTM, I think a diode would do the trick.

Thanks for replies and yes a diode will do the trick the better question is sourcing the diode needed. Being that the battery is 5.4 amp hours I would think I need to stop that current going back so I need a diode at least that size if not bigger. Been trying to source where i can find an inline say 10 amp diode with zero success. fun fun fun

ptm

hmmm, I built some variable speed dc motor controls a year or so ago for a remote camera head. I'll see if I can find the name of the place that i got the parts from online, at home tonight.

Thanks guys had all the parts I needed just was looking for a quicker way. I had a relay which I am told is better then the diode and wired it in and all works great. Cant wait to get this puppy out to the track. Thanks again for the help and a big thanks to Glen Hall who sent me the diagram how to do it.

ptm

5 amp diodes are readily available, you could put in 2 or 3 in parallel to cut the current by 2 or 3.
The black casings can touch so you can twist the ends together neatly and not take up much more room, silver end is positive.

Cheers

www.globalsemi.com

I own a car audio shop and this is where I get alot of electronics parts.
Hamlet is a good guy to deal with.