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All the bits that we need to work with to feed the big 401.
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Dear Genright, please ask your welders to stop creating works of art and shipping them to hacks like us.
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The 24 bolt oval pattern is a standard in the fuel cell industry. We made a template after scoring a drawing online and blew it up to life size.
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When using a jigsaw on aluminum, you want to use larger tooth spacing to keep from filling up with molten aluminum chips. And remember to use lube.
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The internals of the Genright tank exceeded our expectations with a small sump location in the bottom and baffles at either end. Fuel cell foam can be used, but we have a record of seeing it break down with time and harsh fuel additives.
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The internals of Radium’s FCST is nothing short of artwork. With stainless hardware, top shelf electrical connections and anodized everything, it’s tragic to stuff it all down into a fuel cell never to be seen again.
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Mounting of the Aeromotive pumps is straightforward and the included Radium instructions leave little head scratching.
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The depth of our tank required the use of a Radium extended pickup to reach the bottom. Even with the pump up this high, any unused fuel from the surge tank, or the return from the engine, is poured over the pump to keep it cool when not submerged.
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Mil Spec electrical connections are not only a quick disconnect design, but weather resistant as well. Slather a little dielectric grease on the connectors before final installation.
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The fuel level sending unit from Classic Instruments requires a little tinkering to achieve full motion when attached to the FCST. This is due to the baffles in the tank.
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With a little gasket maker in a tube rated for gasoline, we cinched the surge tank down with all 24 ¼-in fine thread bolts. We are not using the FCST vent because Genright includes a rollover valve arrangement already. Radium offers all the parts and components to complete your system if need be. Our EFI system comes with -6 AN fittings, which attach directly to the Radium unit.
Story & photos by Bryan Irons
Building a fuel system capable of fueling Merican Metal Menace
We do our best here at 4WDrive to bring you the latest and greatest when it comes to the Canadian off-road world. This would be much more difficult if a fault in our test rig surfaced in the woods turning us into bear fodder. Editor Irons has zero hope of outpacing our country’s large carnivores, or editors Stanley and Mack for that matter, so we are going to do our best to reduce the chances of becoming a wheeling statistic. The most common break down we come across that does not lend itself to an easy fix is a fuel system malfunction. We knocked on Radium Engineering, Genright Offroad and Aeromotive’s doors to help with feeding our 407CI AMC V-8 trail burner motor dubbed “Merican Metal Menace”.
Most modern fuel systems consist of an in-tank high pressure fuel pump and lines for fuel and vapors to and from the engine compartment; pretty simple from the outside. The pump, typically, is situated inside the tank because it uses the gasoline as a coolant, which extends pump life. Once the tank starts running “low”, the pump becomes uncovered from its cool bath and damage can occur. For us wheelers, extreme angles or bouncing around can introduce unwanted air in the fuel system leading to stalls, lean fuel mixtures and uncovering the fuel pump from its lifeblood of cool fuel.
Epiphany hit us after getting our fuel cell in from Genright Offroad; there is at least one welding savant in California currently employed there. Scope out the pictures we took to find out why! We pulled the trigger on the bolt in “stretch” tank to make room for extending the wheelbase in our trail rig “Stinky Jeep” in the future. The drawback of being able to move the rear axle back 7-in is the loss of 19L (5 gallons) of fuel capacity bringing us down to 57L (15 gallons), not much of a loss really. This is not an expedition vehicle, and most days on the trail see us sipping around 40L depending on the weight of our right foot.
Aluminum is great at dissipating heat generated from the hard working fuel pump(s) inside a fuel cell, and it’s also lightweight. It is also relatively soft, so most of Genright’s tanks leave the factory with a steel skid plate, but our rig it pretty portly as is and for a nominal fee, you can get a beefy skid plate for your tank formed out of aluminum. Our concern with the aluminum skid centres on the materials tendency to gouge and grab onto jagged rocks that it can come in contact with. The structural strength of the skid lies in the design of the internals of the tank, and is more than tough enough to hold up the back end of our BBW of a Jeep. If we do find ourselves getting hung up, a simple layer of UHMW plastic can be adhered to the bottom of the tank making it strong, slippery and still light.
Genright uses baffles, slosh trays and a few other tricks in their tanks to try and ensure that the fuel pickup is always submerged, but we needed more. Entering stage right is Radium Engineering. Normally associated with corner carving tarmac eaters pulling two G’s through chicanes, Radium has developed a Fuel Cell Surge Tank (FCST) that keeps supercars, and off-road rigs on their side, running. Xibit could best explain its inner workings as “It’s a tank, in yo tank, homie!” Seriously! A fuel lift pump is used to move raw fuel from the bottom of the fuel cell into a holding container (the surge tank) where up to three other fuel pumps feed the engine-pressurized go-juice. The small holding container is not pressurized, and what fuel is not used to feed the engine, is poured back onto the primary pump in order to keep it cool.
The Radium FCST is designed to use just about any name brand pump you wish. All you need to do is give them the heads up of what pump(s) you have selected and they complete the build with the proper wiring connections and hose attachments, or they can supply you with the pumps already. We went to Summit racing to score two Aeromotive Stealth 340 pumps able to flow 340 lpm and at pressures up to 90 psi. We are using the same pump models to both feed the surge tank and feed the motor. The two extra spaces inside the sump can be utilized for additional pumps when requiring more fuel or, as in our case, a location for an additional backup pump just in case of a main pump failure. This allows us to easily switch over to our backup pump in just a few minutes. As far as we are concerned, a fuel pump has moving parts and lives in a corrosive atmosphere; they can and do break down.
The pumps fit in the aluminum Radium Engineering setup like a glove. We used one of their pump extension kits to reach into the bottom of the extra deep fuel cell. The unit itself is a standard bolted flange utilizing 24 bolts. Our Genright cell is setup to drop in a Jeep YJ fuel pump; this required us to make a larger hole to mount the FCST. A few jigsaw blades along with the proper drill and tap size allowed us to bolt the unit down to the thick aluminum sheet.
The FCTS comes equipped with two additional holes in the anodized top, one for a fuel level sending unit, and one for a filler hose. Our Genright cell came with filler and vent tubes welded in already, so we ordered a Classic Instruments universal fuel level sending unit to finish the kit off before bolting it down and stuffing it under the Jeep.
We are not going to deny that there is a lot of skrilla tied up in our fuel system seen before you, but we have no regrets in spending the cash on well made parts that will be sure to last the test of our stupidity. With what we have invested in our high output AMC mill, having it run lean and burning a hole in one of the pistons would by far exceed what we have tied up into our arrangement here. Add to that the security that our rig will make it home to the shop without suffering from a fuel system failure we can’t fix in the field; it’s money spent in the right place!
- Genright Offroad – www.genright.com
- Radium Engineering – www.radiumauto.com
- Classic Instruments - www.classicinstruments.com
- Aeromotive – www.aeromotiveinc.com
- Summit Racing Equipment – www.summitracing.com