Fuel Pump

[K7TKA]

I have a suspicion my fuel pump may be going south. Will these bikes run on gravity with a full tank? Mine seems to get bad when the fuel starts getting low. I will lose one or two cylinders. After refueling it seems to run fine. At first I thought it might be a coil problem but it seems to clear up and run fine when the engine is warm. I would think coil failure would occur when hot rather than cold. This could also be a carb problem but it seems to run fine without any problems when the miss goes away. After much thinking about it I came up with the fuel pump Idea. Any suggestions?

 

[Ansimp]

Sounds like you are on the money with the fuel pump

 

[toytender01]

Tom just a thought. Have you checked your fuel filter?

 

[K7TKA]

I'm on my second fuel filter since I cleaned the tank. It's been on for maybe 500 miles.

 

[Steve83]

Well, gravity seems to flood 'em, so it should run 'em! A bit less pressure on a low tank might cause it to cut out.

 

[joedrum]

yep sounds like you got it nailed on fuel pump

 

[ekvh]

Gravity will feed them above half a tank.

 

[AApple]

Are you sure your pick-up tube inside the tank doesn't have a small hole in it somewhere? Have you tried turning the petcock to reserve when it starts acting up? If it still acts up on reserve, it may be the pump....if not, there may be a problem with the main tube. :good:

 

[dan filipi]

The only way I know to test the pump is to check pressure out. Spec is 2-3 lbs, at crank speed I believe. The spec is in the manual. Flow over time amount is in there also.

 

[Ansimp]

I would clean out your pump. I don't know if you used a prefilter after cleaning your tank but you may just have leftovers effecting the check valves in the pump.

 

[Steve83]

Remove the screws and lift the cover off the pump. You can inspect the valves and diaphragm without removing the pump, or even disconnecting the fuel lines. Crank the engine to see if the diaphragm moves up and down.

 

[Ansimp]

Steve83 » Tue Apr 29, 2014 7:44 am[/url]":1j1oaf4t]
Remove the screws and lift the cover off the pump. You can inspect the valves and diaphragm without removing the pump, or even disconnecting the fuel lines. Crank the engine to see if the diaphragm moves up and down.

Just don't have a full tank of fuel with a leaky fuel tap or one that is not turned off :head bang:

 

[Steve83]

Yeah - I guess I should've mentioned that - turn off the petcock first!

 

[K7TKA]

Thanks guys for all the responses. I picked up a used pump today from my local bike wrecker and changed it out. The bike started and ran well for a short test ride. I'll know more when the tank gets low. In the meantime thanks for all the help.

Tim

 

[K7TKA]

Well after running a full tank I got a sputter, switched to reserve and away it went for another 12 miles. I had to break out the lawnmower gas to get to the gas station. I think changing the pump fixed the issue. Now I have to take the pump off and seal it better as it is dripping a bit of oil. Thanks again for all the help.

 

[slabghost]

Always glad for good news and easy fixes. Congrats!

 

[Ansimp]

+1