I recently bought a 1989 Dakota Sport and it came with a DIY installed kill switch. When the switch is in the off position, the car will crank but won't start. When I turn the switch to the on position, I can hear a low hum coming from somewhere below the gas fill inlet - so I assumed that the switch is wired into the fuel pump. The problem is that the switch is wired to a hot 12v source and if I accidentally leave the switch in the on position after arriving at my destination, the pump continues to run and floods my engine and drains my battery.

I traced the two wires that connect to the back of the switch: One wire connects directly to a hot wire with an inline 20A fuse under the steering column I cannot trace the origin of the hot wire but assume it is tapped into the battery or another hot source. The other wire runs through the firewall to the top connector of the ignition coil spliced with the grey wire with black stripe which I believe is a 12V switched feed from the ASD relay. This puzzled me as I cannot figure out how the switch is powering the fuel pump! But I have read that putting a kill switch on the ignition coil is common.

I thought it would simply be a matter of swapping the hot connection of the switch to an ignition-switched source. So, I moved the hot wire and tapped into the A/C fuse. Once this was done, I move the switch to the on position and the fuel pump was silent - perfect. When I turned the ignition switch to ACC position (radio, dash functions all on), I could here the fuel pump cycle on - perfect. BUT when I try to start the car, it cranks but will not start.

I moved the switch back to the hot wire under the steering column, turned the switch on, and the car started without hesitation on the first crank.

This made no sense to me... I cannot figure out how the switch is linked to the ignition coil but controlling the fuel pump. I cannot understand why the car won't turn over with the pump running fed by a switched 12v source as opposed to a hot 12V source.

Thoughts? Thanks for any help!!!

 

Likely the second source you used for power for the switch, isn't powered when in the start position.

I sounds more like the previous owner had some starting issues, and this was his workaround for it.

 

I tested the fuse in both ACC and start position and it had power.... I can live with the switch but it's just annoying to have to remember to shut it off upon arrival at the destination!

 

Think I might be tempted to get a service manual for your truck, and make the system work the way it is supposed to.....

 

I second that. Was my first thought as soon as I read the OP.

 

I third that.

Sounds like he tapped into the ASD line at the coil, and is feeding it from the switch.

For 89, the ASD line also powers the fuel pump.

RwP

 

The person that wired the fuel pump should have at least ran it off a relay triggered by ignition on that is also live when cranking. Its really not the best way but it would work if you never left the key on. The pump should only cycle a few seconds when the key is on and stop if its not started.

I agree it would be best to fix the problem. If its not easy to find I would just wire it better.

 

Thank you for those that replied. Sounds like I need undo this kill switch. I am now particularly concerned as I believe the fuel pump is constantly running while the engine is running....

 

Fuel pump should be constantly running, if the engine is.

 

Ah... got it. I misunderstood Glenn440s comment. Thanks!