BV500: Fuel Pump Hose Clamp Installation
Many many BV 500's suffer from poor performance after about 3000 miles on the clock. The symptoms include: stalling, surging at low speeds, poor acceleration, low horsepower etc. Looking in the service manual is an effort in futility since all of these symptoms require the Piaggio service computer to diagnose. The problem is usually a design issue that fortunately is very easy to fix. Most units have been built without hose clamps on the high pressure fuel line hose coming out of the fuel pump located in the fuel tank. It seems that the problem started with the introduction of gasoline in North America that is blended with Ethanol. It appears that the blending of alcohol into the gasoline causes some breakdown in the fuel line. This causes a loss of proper pressure in the fuel line.

Update 6/1/09 - Piaggio has commenced a recall for this problem. If you have not performed this fix already, your dealer should do it at no charge. The factory instructions are to replace the hose and install hose clamps.
Tools Required
#2 Phillips Head Screw Driver
#2 Standard Blade Screw Driver
Small Hammer
Parts Required
It is important to note that if your pump has the CLEAR/TRANSLUCENT fuel hose, as shown in the picture, that you replace it with a high pressure hose (designed for fuel injection) of the same size. The clear/translucent hose will eventually break down and crack, even if you have installed hose clamps. The recommended fuel line and clamps are available at NAPA Autoparts. The proper part numbers are:

NAPA submersible 5/16" fuel line hose (part # H209)
NAPA high pressure hose clamps (part # 705-1226)
2 ea 10" tie wraps (optional)
It is strongly recommended that you wait until your fuel tank is nearly empty before doing the following inspection/repair.

The inspection and possible repair consists of pulling the fuel pump/fuel tank sender/fuel filter assembly out of the fuel tank and seeing if there are hose clamps and a black hose installed on the fuel pump. If not, it is a simple matter of replaceing with the proper hose and installing hose clamps.
Step 1
Set scooter on level ground up on its lift stand. Open fuel door. Unscrew fuel tank cap. Remove rubber shield around fuel tank mouth. Now remove four screws. Two are inside the fuel door the other two are at the extreme front top corners of the black plastic saddle framework around the fuel filler door. Lift the fuel door end of the "saddle" and then urge the saddle out from under the lip at the rear of the saddle. Then tip the rear end up and over and off to the left (as looking forward). Screw the fuel cap back on to keep crud out of the tank. Things should now look as in the picture at Fig 1.

Figure 1

Step 2
You can see there are two hoses that are connected at right angles into the fuel tank. Where each hose connects, there is a small collar ring. Press downwards on the ring while simultaneously pulling upwards on the respective hose. It should come loose. It will likely leak some fuel when it disconnects. Have a rag ready! I used a tie wrap on each one to hold them up and out of the way. Now disconnect the cable. I tucked it under the fuel cap. Things should now look like Figure 2.

Figure 2

Step 3
There is a screw collar around the fuel tank sender assembly. Use a standard blade screwdriver placed against the ribs on the collar and tap lightly with a hammer. Unscrew the collar. Things should now look like Figure 3.

Figure 3

Step 4
Rock the fuel tank sender assembly back and forth while pulling upwards. I assure you, it will break free and start to come up and out. Once it comes up, you should be careful while lifting it up so as not to damage the tank float (the thing that figures out how much fuel you have for display on the fuel gauge).

There is no need to pull the entire assembly up and out, I would just hold it up with a string or weak bungee cord attached to the handlebars while working on it.

Look at the hose below the white lid. There should be two hose clamps on a BLACK hose. If your hose is clear, as in the picture below, it must be replaced. If the clamps are not there, or you have a clear hose, YOUR SCOOTER IS install some! Buy metal hose clamps for a ½" (12mm) hose. Unscrew them completely and wrap them around the hoses. They should be quite secure, but be careful about over-tightening them. You are wrapping around plastic fittings. Your fuel tank sender assembly should look like Figure 4.

Figure 4

Step 5: Reassembly
It is basically the reverse of the disassembly. Things to be careful about... The rubber ring that is around the white cap, tends to get folded over while reinserting the tank sender assembly. Be real careful that it slides in straight as you push it back down. Line it up in-line with the front/rear of the scooter and rescrew the collar. The two hoses just snap back in place. Reconnect the cable. Unscrew the tank cap, and replace the saddle cover. While installing the saddle cover, take care about the routing of the cable release for the fuel filler door. Install the four screws, the rubber seal around the tank filler collar, and the tank cap. You're done. GO RIDE!
Article originally contributed by pdxscoot
Last Updated Fri Jun 04, 2021 1:27 pm

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