Internal Fuel Pump Mod (VTX 1800)

Posted by Bare | Last Updated May 27, 2014

This is a walk-through for modifying the fuel pump on the 02-04 VTX 1800, this applies to VTX models with the fuel pump located inside the fuel tank. The 2004+ N models and all 05+ VTX’s have an external fuel pump so this mod does not apply to them. The premise behind this mod is that there is always about a half gallon of fuel left in the tank that the fuel pickup cannot reach. This mod helps get a little bit more of this fuel.
In my opinion, this is a lot of work to gain only about 10-15 more miles out of a tank, so this is not a job I recommend unless you already have your tank apart for other work. As always attempt this work at your own risk.

Required tools/Materials

  • 10mm socket
  • Torque wrench capable of 9 ft/lbs
  • Philips screwdriver
  • Lineman’s pliers or Dremel tool or grinder (read low fuel sensor section and decide)
  • Bench vise
  • Hole puncher (like is used for paper) or leather punch

Fuel pump pickup
In order to mod your fuel pump like this, you will either need to ride until your tank is empty or siphon the fuel out. With the tank empty (or pretty close) follow these directions and remove the tank.

With the tank off, look at the fuel pump on the left underside of the tank. It is where you disconnected the hoses when removing the tank, and it has 8 10mm bolts holding it in place. The pic to the right is the pump after it has been removed.

Find a clean surface and put down some soft clean towels to work on so you don’t scratch your paint. Undo the eight 10mm bolts, but know that you will need to break the hex (allen) head banjo bolt for the fuel line loose in order to get to the last bolt. With the fuel pump/pickup bolts out and the unit loose, turn it counter-clockwise until you feel it hit bottom. Pay attention to how much you turn the assembly (use the bolt holes as a reference) and then remove the entire unit. This sometimes requires moving the assembly around to get everything situated so that it will come out. Just remember, it got in there, so it will come out!

With the unit out of the tank, put the end by the mounting plate (left side of pic below) in a vice and bend the end by the fuel pickup (right side of pic below). Remember that a small bend can go a long way, so don’t overdo it. Bend it only a small amount at a time. I have seen some that only require fractions of an inch and some that required as much as a full inch of bending. Bend a little, reinsert it into the tank and turn the flange until you feel the pickup end bottom out. You want to keep bending it until the pickup end bottoms out when the bolt holes all line up. Just remember to do only a little at a time until it’s right so that you don’t end up having to try to reverse the progress you’ve made.

Rubber boot
Once the pickup is bent into the proper position, move on to the rubber boot at the pickup end of the unit (right side of pic above). Carefully remove the black rubber that protects the steel wool pre-filter. Use your hole punch or leather punch to make some holes in the BOTTOM of this piece of rubber. Regarding the number of holes, I believe “the more the merrier,” but be careful not to destroy the entire rubber boot by punching too many holes.

The boot on the left was done with a leather punch, the boot on the right was done using a normal paper hole punch. Again – just make sure the holes you punch are on the BOTTOM of the rubber boot.

Low fuel sensor

With the pickup bent and the rubber boot modified, you can move onto modifying the low fuel sensor. This is an optional part of the mod as some people like having lots of miles in “reserve” after the light comes on. I do not and I think many guys wouldn’t mind the light coming on a few miles later than it does now – so here it is if you choose to do it.

Find the low fuel sensor in the middle of the pickup “arm” (see pic to right).

Remove the Philips screw to give yourself some room to work with the bracket on the sensor. Use your lineman’s pliers, Dremel tool, grinder, or whatever to cut off the existing “tab” that locks the sensor in place and shave the bracket down a bit. Once you have it cut back, bend another small tab out of the bracket to replace the one you cut off. Lock this tab in place and reinstall the Philips screw to hold it all in place like in the picture below.

Feel free to experiment with how much you want to cut off of the bracket depending on how late you want your fuel light to come on. I don’t recommend going too overboard with this since there is no reserve tank on the 1800. This sensor is your last line of defense against getting stranded, and pushing an 800+ pound bike sucks!

With the sensor modified you’ve now done everything you can do to modify the fuel pump assembly, so put the entire assembly back into the tank. Inspect the gasket that goes between the pump mounting plate and the gas tank for defects or problems that could cause leaks. If there are any visible problems (cuts, tears, dry-rot, etc), replace the gasket – this is not a gasket you should take risks with.

When reinstalling the pump, you have to torque the eight 10mm bolts to 9 ft/lbs, and you have to do them in a specific order to ensure the gasket seats properly. Check out the pic below for the proper order, starting at 1 and going through 8.

Now all you have to do is ride the bike and test it. I recommend filling a small coke or water bottle with gas and running the bike empty to test when the light comes on and when the tank runs dry. Once you’ve done this, you can dump the bottle and get to a gas station knowing how this mod has impacted your bike.

As I said at the beginning, this mod will not give you that many additional miles from a tank, and it is a fair amount of work – especially for someone who perhaps has only removed the tank once or twice. I would not spend the time doing this mod unless I had the tank off the bike for another project. BUT if I did have the tank off for another project, I would definitely do the mod. It’s easy to do, and one day it might help you get that little bit of gas you need to avoid being stranded. Heck, if nothing else, I like having the dash light come on a little later!

One Response to “Internal Fuel Pump Mod (VTX 1800)”

  1. Tim says:

    Great write-up, thanks! Also, just a thought on your comment about running the tank until empty after the mod and carrying around a spare jar of gas….This engine is fuel injected, so I wouldn’t recommend ever running it down to empty. Aside from fouling the injectors, it could also damage your fuel pump.

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