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How To: Install or Relocate Your Fuel Tank
& Add a FiTech EFI Conversion Kit

Project Overview

Relocate the fuel tank from inside the cab to under the bed. This opens up storage space and eliminates the fuel vapor from inside the cab. Also, learn how to convert your truck to a fuel injected vehicle offering better gas mileage and easier starts at an affordable price.

For more information about the FiTech EFI Conversion Kit, click here.

Video Transcript »

Project Difficulty

(1 star being easiest)

Estimated Parts Cost


* pricing subject to change

Estimated Project Time

6-7 hours (Relocate Gas Tank)

8-9 hours (EFI Conversion)

Required Tools:

  • Basic Hand Tools
  • Pneumatic or Electric Cut-Off Tools
  • Thread Sealant
  • Spray Lubricant
  • Welder
  • Soldering Iron

LMC Truck:

Hey guys, I'm Kevin Tetz working with LMC Truck to bring you some tech information and how-to videos that we hope make your truck restoration project even better. In this video, we're going to walk you through the process of relocating your fuel tank from in the cab to under the bed of the truck. There's a lot of good reasons to do that, you can open up storage behind the seat and get rid of that nasty fuel vapor that we all know and love with these vintage vehicles.

We're also going to walk you through the process of a very simple fuel injection conversion that allows you to bring your vintage truck up into the 21st century,get better gas mileage, easier starts and it's surprisingly affordable.

Now you don’t need to pull the bed off of your truck to do the fuel tank conversion, but we wanted to show you exactly what we’re doing and exactly how we’re doing it, so we pulled ours off to get you a better view. We pulled the tank out just because it was coming out anyway. Now in pulling our tank out from behind the seat we found out that it had a leak in one of the seams, so it puts an exclamation point on the good reasons that there are to pull the fuel tank out from in the cab floor, we’ve gotta get it out of here.

LMC Truck gives you plenty of options for relocating your fuel tank including the 17-gallon tank with the fill neck in the top so it goes through the bed floor. The interesting thing here is that they machined a return vent, it could be an EFI return or just a tank vent. The point is you’ve got options including a larger 20 gallon with the side fill. If your fuel tank won’t fit in between the frame rails they offer a strap kit as well as anti-rattle and anti-squeak components so your tank doesn’t jiggle and rattle and squeak going down the road. Fuel delivery, well you need a sending unit, these will match your factory gauges and give you options for connectivity. If you need a fuel cap again there’s more options including this keyed one that gives you more security. This is an inline fuel pump kit which includes everything you need to get fuel to your EFI system. Fuel rated hose, fuel pump and all the push-lock connectors and clamps you’re going to need, and it’s made to be used with the FiTech EFI Throttle Body Conversion Kit and of course it’s all available from LMC Truck. This is the FiTech EFI Throttle Body it’s got all the sensors and all the connections that you need. It’s multi-pin connectors and a 5 wire hook up and you’re fuel injected. LMC Truck also offers the option of the FiTech Command Center which allows you to keep your original fuel tank and your original mechanical fuel pump and pressurizes the fuel for the requirements of the EFI. You’ve got a handheld controller to help program the system and all the cables to do that and the rest of it, it’s self-learning. Now you’re probably not going to use everything we’ve got laid out on the table here, but it’s nice to know that a company like LMC Truck has got all the pieces and parts that you’re ever going to need regardless of the direction that you go with your project.

Our spare tire occupies the same real estate as the tank does so it’s out of here. The tire carrier came out easy once we cut the frozen and rusted mounts off, that’s kind of to be expected with a vehicle this old. This crossmember goes away to make room for the fuel tank and it was riveted in, we cut the rivets off and it’s fairly simple. None of this project is really that complicated and it’s all for the most part bolt-in but I’m going to give it a 4 out of 5 just because we’re dealing with so many different components and systems all at once.

For tools, you’re going to need basic hand tools maybe some pneumatic or electric cut-off tools but it’s not that complicated. Just make sure that you got a good full toolbox or you know a buddy that does.

Now keep in mind this is a temporary mock-up of the tank. If your bed’s already on the truck, then you’re not going to be able to get these nuts and bolts. You might want to think about a captured nut set up. Once you’re done, for now, we’re just going to use a simple nut and bolt to hold it in place. Just going to cover up the holes, make sure nothing falls down in it. The sending unit needs to be carefully inserted into the tank. For our setup, we’ve chosen the traditional rubber hose and clamp hook up. LMC Truck offers the different quick-connect version for inline fuel pump delivery setups.

Now it’s really important to have all 3 tabs underneath so you’ve got an even clamp load on your rubber gasket but you’ll know if you do, more importantly if you don’t. All right, it’s seated all our tabs are in place, senders installed, now we’ve got to ground it. We lucked up with an existing frame hole we don’t have to drill. The important thing is to have a bare metal contact for a perfect ground. Now we’ve got something to pour fuel into when it comes time to start the truck. Nice! Let’s make a jumper wire to the original fuel sender that we way our new dash gauge is going to work. Now the only other thing that happens back here is to run the fuel feed line to the sending unit and the vent to the vent bung, everything else happens under the hood.

Now in the same way that you don’t need to pull the bed off your truck to do relocate the fuel tank, you don’t really need to have the hood off the truck to do the FiTech EFI swap. We just wanted to give you a really clear look at what we’re doing so you can do the same thing. Now my buddy Jeff is pulling off the original fuel pump because although it works, we’re not sure how many miles it’s got or how much life it’s got left in it, so we’re going to replace it with one we got from LMC Truck just to make sure it doesn’t become an issue.

The other thing that’s critical here, this is mandatory, make sure that you disconnect your battery, you’re dealing with a very sensitive electronic computer and you don’t want to send any spikes. You want to make sure your connections are made before you connect it back up.

The old fuel pump comes off with SAE hand tools and we got lucky because the gasket came off stuck to the pump. All the rubber lines are getting replaced but this steel line that goes from the pump to the fuel feed is getting reused, the rest of it well it’s pretty straightforward, it’s just swapping out the pumps. This is a very simple system to install but keep in mind there are detailed instructions that come with the kit that are also easy to follow.

Now unbolting a carburetor is very simple, but the linkage itself, since this truck has a 700R4 transmission, well, the TB cable stays, the rest of mechanical linkages, janked up as it is, it’s getting reused for now. Look at that. There we go, there’s some professional stuff right there. Return springs.

We clean the debris off the intake manifold just we don’t knock anything down inside the engine. Next we install the new temp sensor that came with the FiTech Kit. Make sure you use a sealant on the threads. Jeff’s got the FiTech TBI on sideways for better access to the vacuum ports on the back. We’re reusing the vacuum advance tubing and it gets plumbed into a specific port on the back of the throttle body. Alright we need some gaskets. One of the supplied gaskets goes underneath the throttle body, and we fasten it down with some nice-looking button head fasteners. The crankcase ventilation tube gets routed to the back of the throttle body, the instructions are very clear as to which ports you need to use. The rest of the ports, we’ll leave capped because there’s nothing else that requires vacuum from this engine.

Next, we can start plugging things in, starting with the temperature sensor, after that we’ll plug in the main harness and now we’re ready to wire up the specific components. The FiTech EFI System only requires one oxygen sensor, and you can pick the bank that you want to put it in. We’re using the passenger side and it needs to be 2” to 4” from the collector which is right about here so our location is here because we got clearance on the C channel of the frame.

Now FiTech gives you the option of clamping on the fitting for your O2 sensor. These clamps combined with the curved faceplate and a very crushable sleeve will get you a good seal, but like with any good electrical connection it’s always best to solder. For something like this it’s always best to weld it so we’re going to keep the system permanently on this truck, so we’re going to weld our fitting in place. Perfect! Put the sock back on the rooster, right there. Now, gravity will hold it in place while we weld. Yep, alright our threads are good, we’ll let that cool down, we can put it back in the truck. Make sure there’s anti-seize on the threads of your O2 sensor, then you can snug it into place on the fitting. There we go. The oxygen sensor harness gets routed up above the frame rail and connected with the harness from the EFI. We’ll route it safely out of the way from the exhaust later on. To reconnect our exhaust pipe, we used a wide band style clamp, that seals perfect.

Now we’ve got to install the command center. Since we’ve chosen the FiTech command center as our fuel delivery method. Now there’s plenty of options in this engine bay but there’s a few things to consider. For instance, you don’t want to be too close to a heat source, like the exhaust manifold, so you got to be out of the way of the spinning parts so here’s where we’ve chosen to install ours.

In order to keep the command center in the right orientation, our buddy Jeff made up this bracket that mounts it perfectly to the apron. We use the supplied dash 6 fuel line to route from the mechanical pump with plenty of excess line. Now here we’re just mocking up and doing a rough plumbing set up on the fittings and hoses. Then we routed the line up to the fuel inlet port of the command center using a supplied 90-degree push-lock AN fitting.

Next the high-pressure fuel line gets routed to the throttle body inlet. Slack, that should give us plenty of room. And the excess is trimmed to fit. Use a heat gun to soften up the fuel hose. Here Jeff is using some common spray lubricant just to make the process go a little easier, and then a whole lot of pressure to push past the barbed fitting until the hose is seated. Alright thanks Jeff.

OK so our fuel supply line is finished and we’ve got the push lock connectors on, and as you can see we’ve got an inline fuel filter in between the command center and the inlet on the throttle body because the FiTech System needs that. Now the command center needs to be vented, here’s a port for the vent tube this is the vent line that goes back to the fuel tank. The fuel supply hose from the tank gets pushed on to the fuel pump and it gives us a fuel circuit. There. We’ve got our fuel lines routed inside the C-channel of the frame and the small one which is vented from the command center goes into this port here on the tank. There’s plenty of slack. It kind of goes without saying but make sure you route your fuel lines safely and out of the way of anything that spins or moves, as well as away from your exhaust system, and always use fuel rated hose designated for the pressure that your system requires.

Alright like we said the command center needs to be vented that’s what the smaller line is for, so the tank needs to breathe. You can do that two ways, either have a vented cap which this one has an o-ring and is sealed or you can do a vent right here which makes this LMC Truck tank really nice. This is a great spot for a rollover or tank vent for mechanical fuel pumps or for installing the inline fuel pump return line if you need a return style system. This is the return line on the throttle body this is our configuration and the command center. We go returnless, we are going to cap this off with the plug that’s supplied in the kit.

Now this throttle body gives you 3 options for an inlet for your fuel supply. The one that made the most sense to us was this one on the driver’s side rear, right here. Now that we know where all our fuel lines are going and all the hoses are terminated and finished, you can carefully use a conventional wrench or a proper AN fitting wrench to tighten the fittings without scratching them. The command center gets grounded, and we’re going right to the battery from this terminal. This system is very simple to wire. This goes to the positive side of the command center. The red goes to the battery, this yellow wire, well, it’s for a fan controller we’re not using one on this truck, so it gets bundled out of the way. The other three wires go to the coil just follow the instructions and you’re home free. It’s very easy.

You’re also going to notice that we’re using shrink-wrapped and soldered joints only, this is the best way to do an electrical connection and it’s what’s recommended with this system. If you’ve never seen something like this done, check this out. First things first I’m going to slide my shrink tubing over top of the wire. Next we’re going to do what’s called tinning the wire. You can see the copper change color then you know it’s hot enough to take the solder. Doesn’t take much. Yep, there we are. I strip the plastic insulation off of my ring terminals always because I want to do a joint like this. Make sure that I’ve got a good contact. Of course, we’re preheating, and I can watch the tin solder joint ‘til it changes color and that’s what you call a good solder joint right there, and it took seconds. Let that cool a little bit. Slide my shrink tube up. Now I don’t like to use that intense heat. I like to use a lighter. I can control the tubing without burning it and now we’ve got a perfect solder joint and a nice-looking ring terminal.

Since we’re using a traditional coil with electronic points we’ll wire up to the coil, but if you’re running an ignition box there’s different wiring for that. Again, it’s all in the instructions. We reused the previous owner’s hardware and reconnect their throttle cable and TB cable from the transmission to the carburetor linkage. With everything else connected and wired we make our final connections to the battery terminals. Then connect the terminals to the posts just to make sure that there’s no surges to the computer.

And since this is an entirely new fuel system that’s completely dry, we threw a couple of gallons of gas in it so we had some fuel to start. LMC Truck even offers a pre-bent and pre-cut filler plate for the 66 C10, putting the icing on the cake of the tank relocation project. With the coil wire disconnected I cranked the engine over, Jeff was watching the gauge on the command center and verified that we had fuel pressure from the mechanical pump. Yep, we’re primed, cool.

Now we’ll get to set up and program the computer to our truck. Once you go through the initial setup using the handheld controller this EFI System is self-tuning making it a very simple installation, the setup prompts are easy. Just answer the questions - How many cylinders you have? Engine displacement? What kind of cam you’ve got? The Rev limits that you want? Idle speed setting? And what kind of ignition system you’re running? By the way, make sure you go through this menu with the ignition key in the on position so the settings will eventually get stored into the computer. Going to shut the key off, so it stores the settings. There’s prime. Keep in mind driving the vehicle on the road is the best way to help the self-learning process. That’s it - and the unit will adjust for optimum performance. Horses running good. Awesome. /p>

Well that’s how easy and simple it is to convert a 50-plus year old vehicle to electronic fuel injection, plus relocate the fuel tank from in the cab to behind the rear axle. We hope we passed on some great tips that will help you make the decision whether to go EFI and how to do it as well as relocate your fuel tank. Don’t forget to go through the LMC Truck catalogs or go to for more ideas on how to make your truck project even better. For now, I’m Kevin Tetz. Thanks for watching.