My original goal was to have the dual pump project be an automatic setup. If one pump fails, then it would switch over to the backup pump. I quickly ran into a problem when I tried this. The problem occurred when the truck was first started. Since the pressure was at 0 at a start, the switch would read read 0 psi and always flip over to the backup pump. I had to come up with some way to start the truck with the primary pump.

So I built a circuit that would trigger a relay for about 5 seconds when the truck starts. This would force the primary pump to be used for 5 seconds on start up. This would give the pressure a chance to build before reading the pressure from the pressure switch.

I also added a 3 position toggle switch to the electronics that would allow me to choose which pump I wanted to use or put it in automatic mode. With the switch I can force it to the primary or backup pump or let it ride in automatic mode. I put the circuit board in a small project box and mounted it under the hood. I ran the wires for the toggle switch through the firewall and into the cab.

After adding this switch, I have only driven the truck about 200 miles. So far it has worked quite well. I have also decided that I am going to add a light or some type of indicator on the dash so that I know which pump is actually being used. So that means there will probably be a part 3 to this project in the near future.

I also decided to just stick with the in-tank pump as the backup pump. I ran into a problem where I put some summer fuel in my tank which did not have any anti-gel in it. Needless to say it gelled on me. The weird thing is the in-line pump gelled, but the in-tank pump did not. So I figure that was good enough reason to stick with one out of tank pump instead of 2 out of tank pumps.

I have had some people ask about the circuit board that I used for the electronics. I am not going to release the schematic at this time because I am still working on some bugs and would like to make it better. I may offer this as a kit in the future so check back here at a later date.