Fuel pump not priming?

[Cruiser]

I've ridden this bike twice. First time no issues. I got used to tapping the start and hearing the pump pressure the system, prime itself. Today was a bit odd. Had to mishaps, ramp came loose loading the bike at the house, almost lost the bike out the back of the truck. Then unloading, the second the front tire hit the ramp the ramp came down. I ran it before loading. Now it wouldn't start, no fuel pump. Tapping the start would flicker the light for the low fuel, which like many is on the whole time it's running, but instead of staying on a couple seconds it lights as you crank and right back off. Checking over all the wires it started to work again. It starts and runs but doesn't pre charge the fuel like it did before. Has any one else seen this? I'm sure it's going to be a loose wire or something but it be easier if I had an idea which one or ones to check first.

[ricoyam]

It must be pumping or else the bike wouldn't start. It needs to have fuel pressure to start and run. If not, the injector is just opening and closing without passing fuel.
There is a tip sensor which I believe shuts off the pump after 5 seconds. Not sure if these are resettable or not.

[GMP]

"Tip sensor" on a dirt bike? Really?

[bikesparky]

"Tip sensor" on a dirt bike? Really?

Yes, to avoid your leg or arm turning in to mince if it gets caught in the rear wheel after you bin it.

To be honest I don't think it's the tip over sensor as it's a little pendulum that returns to the normal position with gravity. If it doesn't work the bike still starts but cuts out after a few seconds. Even if it is stuck, a little bit of movement should make it fall down again.
I would look at the connectors to ecu and pick up. The way it works is that the pump gets primed when you crank the engine and them when the ecu gets a signal from the pick up it keeps it going.

[Cruiser]

It pumps once cranking enough. Had to kick it a few times. It doesn't, or most of the time charge up the pump. Once running it runs. But if you just bump it, it should pressure the fuel rail, then it starts easy. This only runs the pump when cranking. I'll check the switches and connections again. It's going to be a loose connection I'm sure. Or maybe the crank/start switch itself.

[Cruiser]

And tip sensor? I doubt it cause this bike runs upside down. Got it hung up on crossing some blowdown trees and my buddy grabs the bike from the front, forgot I have a rekluse and hit the throttle. It got traction as I had just heaved it over a double tree top onto soft loam.. In turn got a face full of bark dust, loam etc. bike did a 180 and ended near upside down but luckily not down the ravine. Bike never even thought of shutting off.

[GMP]

And tip sensor? I doubt it cause this bike runs upside down. Got it hung up on crossing some blowdown trees and my buddy grabs the bike from the front, forgot I have a rekluse and hit the throttle. It got traction as I had just heaved it over a double tree top onto soft loam.. In turn got a face full of bark dust, loam etc. bike did a 180 and ended near upside down but luckily not down the ravine. Bike never even thought of shutting off.

That makes more sense. My Ducati and VRod had the lean sensors but that was to be expected. They also had a CAN bus that simplified the harness to all the sensors.

To anyone in the know about the Synerject system: How does the pump know how long to prime the fuel rail? Simple timer, or pressure sensor/switch?

[bikesparky]

That makes more sense. My Ducati and VRod had the lean sensors but that was to be expected. They also had a CAN bus that simplified the harness to all the sensors.

To anyone in the know about the Synerject system: How does the pump know how long to prime the fuel rail? Simple timer, or pressure sensor/switch?

All fuel injected KTM and Huskies have a sensor, lots of others too and pretty sure the Betas also. On the KTMs it lives under the ecu.
I suspect it's a safety- legal requirement in most countries.

In regards to the priming, it's just a timer. Can't have too much pressure as the regulator bleeds it off. (in the tank with the pump)


EDIT: Just had a look at the diagram and it's the same as the KTMs. Nr 55 on the parts diagram, electrical page.

[Cruiser]

Found the lean sensor, mounted up just above battery. I checked the connection to this and popped the headlight off and tested again and now seams to be working. Tap the start to just hear the starter click and fuel pump runs and pressures up. I tapped on the lean, tip sensor and could not get it to not fire up. So right now it's working. I'd like to know what it is exactly.

[GMP]

Is it a CAN bus system? If not, should be fairly easy to defeat.

I looked and found no schematic in the owners manual.