Search all blog posts here.

Search This Blog

Friday, November 18, 2011

1500 Vulcan Fuel Pump Bypass - Permanently

So the fuel pump on my 1500 Vulcan crapped going down the highway. I managed to bypass it on the side of the road and I got to where I needed to go. But why does a carburetored bike need a pump? Especially considering it worked without one until the fuel in the tank got lower than the highest spot in the fuel line. A fuel pump also costs about $300.

So here's the stock fuel line routing. The fuel goes forward from the petcock instead of going directly to the carb. (This because the stock air box is in the way of a direct gravity feed to the carb.)

The fuel line goes forward and up, then to the filter. Basically as shown here.

Through the filter and to the pump, then finally the carb.

If the petcock was right facing instead of left then going to straight to carb would be simple.

So I had this great idea to buy a 500 Vulcan petcock that is right facing and vacuum operated, too.

Well, the 500 petcock will bolt on to the take, but the vacuum port won't clear the rocker box. I should have bought a 800 Vulcan petcock. It the output for the 800 points down and the vacuum port does not stick out behind.

So I'm back to my first plan. Modify my stock petcock to right facing. Some drilling, tapping, and a plug should get the job done.

Tear it down and remove the output fitting, too.

Drill the blind end out to same diameter as the stock output size.

A hole all the way though.

Drill the stock output side only to the tap size for a 1/8 pipe plug.

Tap it.

Pipe seal the plug threads and install it.

I figure a little sealant on the brass output nipple wouldn't hurt either.

Press the nipple in.

Finished modified petcock.

Here's the bypass that got me home.

This is the hose from the filter to the pump. Notice that like the 800 the 1500's petcock output is larger than the carb inlet. I will use this hose and the stock filter, so I won't have to buy universal filter with two different fittings.

The bend in the hose is about right.

Stock filter and new straight line to the petcock.

I put some gas in the tank and then drained it back to only a reserve amount of fuel. I plan to do the shakedown on reserve because this is were the fuel flow will be the slowest. If I can run 65 mph on reserve without spurting and the petcock doesn't leak, then I will can it a success.


  1. The bike ran fine on reserve, but I am a bit concerned about flipping over to reserve on the fly. We'll see how that goes soon enough.

  2. Okay this needs some refinements that I will be publishing shortly.

    1. I have 95 Vulcan 88 1500,, and you can bypass the pump you have to first plug the 2 brass fittings that are near the opening of the carb the side where air goes in I did it for an experiment and I'll tell you it runs smoother and runs like a raped ape and I put a hundred and fifty miles on my tank with no problem the only thing I did was usually fuel output and not the reserve and ran a direct line plus I use pod air filters eliminating the stock air boxes it works really well and it never crossed out at a hundred miles an hour it seemed like it had more power then running the pump and stock air filter kit

    2. OK do I have to bypass the air boxes to make this work?

  3. I gave up and just dumped $300 on a fuel pump and related parts for the Kawasaki. The gravity by-pass will get you off the side of the road, but it wouldn't beat a heavy headwind, do 100 mph, or get the last half gallon of gas out of the tank. It will vapor on a 100° day, too.

  4. I have a 96 vn1500 and the fuel pump is constantly pumping when I hit the start button and ends up flooding. Would this be a bad pump? Someone said I may need to clean my carbs.

    1. This comment has been removed by the author.

    2. The float needle is bad or there is crude in float needle seat.

  5. I have a 1997 Kawasaki Vulcan 1500 fuel pump keeps going bad have replaced it twice the first time I rode it about a tank of gas and it quit running got another and now it won't start any suggestions