Have I got a failing fuel pump??

[oddshapedballs]

So, once I've used approx. 260 miles worth of the fuel in my GSA it seems to struggle a bit, it has what feels like a hesitation on constant throttle. Completely goes away after a fill up.

Is my fuel pump on the way out?

 

[Pukmeister]

If you stop the bike, get off and lean it to the left do you hear lots of fuel sloshing back from right to left? Does the bike then restart and run fine?

If yes, your pump is not delivering enough flow to both supply the engine and drive the fuel return venturi pump (sucking jet pump).

 

[Bendy toy]

Mine did the same hesitation. New fuel pump sorted it.
Look on eBay about £30 for the motor kit.




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[oddshapedballs]

Turned out to be the Fuel Pressure Regulator.

 

[Bendy toy]

Turned out to be the Fuel Pressure Regulator.

How were you able to prove that was the cause? I'd like to check mine.

 

[oddshapedballs]

I gave it to BMW, they are able to test the pressure, mine was constant up/down/up/down - hence the hesitation, fitted the new regulator and the pressure sat at a constant. Rode it home on quarter of a tank of fuel and all feels fine.

 

[Kenny Rodkiss]

Why did filling up the tank make your symptoms go away?
Fuel pump supplies the pressure and the regulator bleeds off excess back to the tank.
If your regulator was faulty you would think it would show up no matter how much fuel was in the tank.
Glad you got it sorted.

 

[Bendy toy]

I gave it to BMW, they are able to test the pressure, mine was constant up/down/up/down - hence the hesitation, fitted the new regulator and the pressure sat at a constant. Rode it home on quarter of a tank of fuel and all feels fine.

Mine with the old pump certainly ran better with a full tank than an empty tank. It also hunted at speed which was probably the pump barely keeping up with the regulator. That was all solved with the new pump.