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  • Assassin Mechanical Fuel system Installation

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    My very first step was to install the draw straw. To do so, either the bed has to be lifted off of the truck, or the fuel tank has to be removed; I chose to remove the fuel tank. If you do not know how to install a draw straw, here is a write up on draw straw installation: http://www.cumminsforum.com/articles/articles/35/1/Vulcan-Draw-Straw-Installation/Page1.html After the draw straw is installed, and the proper fittings installed on the straw, get the fuel tank into position to be reinstalled. Next, it is time to mount the crank hub. This step is much easier to accomplish with two people. One person to keep the engine from turning over, while the other person loosens the 4 bolts that hold the harmonic balancer in place. Remove the bolts, and install the crank hub. Reinstall all 4 balancer bolts. After that, you can go ahead and install the crank pulley. (pic1) Next comes the pump mounting bracket. Remove the oil pan bolts at the very front and center of the oil pan. (oil will not come out) Install the mounting bracket using the (2) supplied allen head bolts. (pic2) Next, install the proper fittings to the pump itself. Minus the fuel line, your pump plumbing should be setup similar to this: (pic3) Now you can bolt the pump to the bracket. Now it's time to measure your fuel lines. Start with the pickup line at the draw straw, and follow the stock lines on the frame rail, and then go above the starter, under the VP44, over the steering box, and over to the Assassin. Be careful where you place your lines, and make sure steering linkage cannot harm the lines. Once that line is installed, now measure the other part of your feed line. From the "out" side of the Assassin, route your line back over the steering box and under the VP44, and go up to the filter housing. There you will connect your line to the supplied tee. Now remove the stock banjo bolt on the fuel line coming from the stock lift pump, going into the filter housing. Install the supplied male to male webber fitting in place of the banjo bolt, and then attach your 6AN 3/8" 90* fitting to the webber fitting, like pictured below: (pic4) Now comes the tee on the feed line, The feed line coming from the Assassin ends at a straight female push-loc hose fitting. That fitting attaches to the tee, and you have another female straight push-loc on the side of the tee, and then use a short piece of fuel line to connect the tee to the 90* push-loc on the fuel filter housing. The end of the tee is female, and the male regulator threads right in. On the end of the regulator you will attach the return line using a straight female push-loc fitting, and then the return line goes down to the frame rail. This picture was taken beside the VP44, facing toward the firewall: (pic5) The next step is collecting the return fuel, and returning it to the fuel tank. There are two ways to do this - I'll explain how mine is setup first. The return line begins at the back of the regulator, and comes down the firewall and then to the frame rail. On the frame I have a tee that the return line connects to, and the return fuel coming from the Assassin run straight through the tee. Now, up near the head, there is a factory tee that collects return fuel from the VP44, and the injector return. I cut the hard line right below that factory tee, and slipped a piece of 3/8" hose over it and clamped it. That 3/8" hose connects to the tee on the frame rail, and ties the VP/injector return with the Assassin return, and all the fuel goes back to the tank in one return line. Line 1 is the Assassin return; line 2 is stock return. (pic6) Here you can see where I tied into the stock return, and ran it into the tee: (pic7) (pic8) Option #2 for a return line setup: The draw straw has 3 ports on it - 1 for pickup, 2 for return. So you can run one return line for the Assassin only, and run a separate return line for stock return fuel. I have a suspicion that running a single return line puts some back pressure on the system, and causes slightly higher fuel pressure while under throttle. I might upgrade my return lines to option #2, and see if it brings down my top-end fuel pressure, but both setups work fine. Also, a threaded plug is included in the kit to plug the 3rd port on the draw straw if you decide to go with return line option #1. Once the fuel lines are completed, the fuel tank can be reinstalled. As far as disabling the stock lift pump, I just unplugged it, and left it there. Now it's time to prime. I used an electric drill, and the belt on the lift pump pulley to spin the pump and prime the system. (be sure you spin the pump the right way, so you're pulling fuel) I also pressurized the fuel tank with air, and after a few minutes of using the drill, fuel should reach the VP44, and then make sure the lines are buttoned up, install the belt properly, (crank pulley to lift pump pulley) and crank the truck until it starts. Sometimes this process takes an extra helper to either bleed the line at the VP44 while you're cranking the truck, and the injector lines might need bled. (pic9) (pic10) I will point out the one possible negative about installing this system. After taking out the oil pan bolts, and reinstalling them, a small oil leak has been created. Some people have trouble with that, and others don't have any trouble with oil leaking. But honestly, I'm not worried about it. This pump has been installed for 8 months, and has about 1,200 miles on it, and I think I lose more oil when I wipe the dipstick off, so it's not that big of a deal. I'm sure some good quality sealant, and properly torquing the pan bolts could fix the problem. Be sure there are no leaks, and the fuel system will stay primed, and the truck will start just as fast, if not faster than with an electric lift pump.

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