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If you don't mind a little re-pinning you can use the stock bulkhead connector on these sending units to get both of your power feeds into the tank, that connector is rated for a lot of current, I use the pins that were originally power and ground for the original pump.
I did this, then I just drilled 1 hole for my grounds. Instead of passing the wire through, I ran a screw through the sending unit as a stud with both pump grounds bolted to it, then on the outside a ground from that directly to the frame. The level sender wires remain untouched. Then I setup my "hot wire" harness so the factory relay tries to turn on both pumps, and I have a ground loop on the 2 pump relays that let me play with which pump runs. One has a connector to it with just a loop, so whenever the truck wants the fuel pump on, that fuel pump is on, the other ground loop goes to my Hobbs switch. I used the same connector for the Hobbs and for the loop so I can swap them from time to time and make sure I use both pumps. I swap them when I change the oil...plus if my primary pump does fail, I can swap again and use the second pump to drive the truck home, just can't make boost because I'll run out of fuel with only 1 pump.
I think I bent the float arm when I reinstalled the sending unit...full reads 3/4 tank and I get nervous about what my fuel level really is when it's low, so I fill it prematurely...I'm not motivated enough to drop the tank again to fix it right now though, probably won't until the spring when I also need to replace the cross member above the tank...seems to be the only thing on my frame that's corroded, and it's pretty bad. I don't think I screwed up the EVAP, it seems to fill normally until the pump clicks off.
I am considering doing this to my 2000 RCSB truck. I have to keep the fuel level above 1/4 tank as is. It can be annoying. My question is, since I have a short bed, does this swap still apply? I'm not sure if the 04-06 tanks were different sizes like the 99-03 tanks were.
I want to thank this group for providing such good information and help avoid having to spend crazy money to get a nice dual pump setup.
My 08 Silverado recently had the oem pump crap out and I was considering purchasing a dual setup and when I search the web I found units ranging from $700-$1200. I was not going to pay that and read up on forums on how to garage build a 2 pump setup without breaking the wallet.
I started with ordering a new fuel pump from Amazon for $55, some AN fittings $50, 525lph pump $90, 255lph pump $70, Y pipe/tubes/hobbs $60.
I swapped the OEM pump with the 255lph as it's the same dimensions and I think 55lph bigger then oem. Wired tied the 525lph pump next to it, connected both with a Y and ran out top with - 8an fitting. I used the factory fuel entry as a return and ran it down to the bucket with 3/8 barb to help gas return near the pickup screens. I did have to hack the bottom a bit but that was to be expected. I wired the 255lph to the factory plug and ran the 525lph out the top to 2psi Hobbs switch with negative trigger on 40 amp relay. I'm still waiting for the wire bulkhead in the mail so it can be a safe seal. In all I'm in for about $350 and a little of my time which was well worth it. The 255 is good up to 600hp and the 525 can easily handle 1000hp.
The reason I went this route was not to go crazy with a Hotwire kit as the factory harness can easy support the 255 as it spikes up to 15 amps and factory supports upto 20 amps. 525 is there when I get aggressive on boost so the 40 amp relay wired through a Hobbs switch does the trick so pump only runs when I get on it.
Definitely would not have attempted this myself if it wasn't for this forum and members sharing their solutions. Thanks
11-29-2017, 01:17 PM
