Cutting out with rev counter bouncing off zero at same time

John Martin · Post by **John Martin** » 1 year ago

Hi All. Help needed please! Out this morning and bike started cutting out or missing a cylinder with rev counter bouncing off zero at same time. 2001 VRap 1000. Filled with fuel and it seemed to be fine for about 50 miles then started again. Any suggestions???? I'm thinking potential coil pack issue. Any help greatly appreciated

John Martin · Post by **John Martin** » 1 year ago

andybaggies · Post by **andybaggies** » 1 year ago

Filled with fuel and it seemed to be fine for about 50 miles then started again

To me that would point to something awry with the fuel system. Perhaps the fuel pump filter is clogged up to a certain height hence it's ok for 50 miles.

Is there old fuel swilling around in the tank with perhaps water ingress after laying up?

Or perhaps the 50 miles gets the engine hot enough to cause an electrical issue. I've had a coil fail but this knocked out one cylinder permanently and I've also had the connections to the coil(s) give intermittent misfires especially after heavy rain. These connection are really small and are a pain to access, they're behind the engine mount on the RHS, and it's worthwhile taking them off & cleaning & tightening the connections.

Usual checks on the HT leads & plugs is also advised.

John Martin · Post by **John Martin** » 1 year ago

Cheers for the advice. Bike was repainted and tank was sealed before paint. Was completely dry and E5 super only used. I've had coil packs give intermittent faults on other bikes. Is the fuel filter within the pump housing? If so I should've replaced when tank was sealed. In my mind it feels electrical due to rev counter behaviour when it happens. There was plenty of fuel in tank when it 1st happened

andybaggies · Post by **andybaggies** » 1 year ago

Is the fuel filter within the pump housing? If so I should've replaced when tank was sealed.

The filter sits next to the pump with various pipes etc on a mounting plate with a coverall 'bag' over it all. I couldn't find a direct plug and play replacement filter so resorted to tapping & blowing any crud loose. Note that resealing the pump unit can be a pain so, as you are thinking, it may be best to address the electrics first.

In my mind it feels electrical due to rev counter behaviour when it happens. There was plenty of fuel in tank when it 1st happened

You may well be correct so as I mentioned check coil connections, HT leads and spark plugs. Note that it uses old style coils rather than coil packs.

And a couple of left field thoughts worth checking, loose fuse/battery connections or perhaps the reg/rec is on it's way out.

Aussiejoe · Post by **Aussiejoe** » 1 year ago

Sounds like to me that the fuel drain barb is blocked, which also doubles as a fuel tank vent pipe and is causing a vacuum in the fuel tank. Look under your tank where the overflow pipe attaches, and there's an alloy barb that screws into the tank, unscrew it and if a heap of crude comes out, there's the problem. If it's blocked, water will also be seeping into the tank when the bike is rained on. Might need to blow it out with compressed air. It's a common issue with the Raptor, that same barb corrodes on the Navigator, but the Navigator tank has a seperate breather tube.

John Martin · Post by **John Martin** » 1 year ago

Cheers for the tips folks. I think it was something more simple. Discovered when fitting tank I removed battery and sensor behind it to get battery out. Not sure what the sensor is but it has a short moulded pipe. Could be air temperature. 1st thing I noticed was the sensor had come away from mounting so replaced bolt. Assume this should earth to frame. Then discover live battery cable loose. I've tightened everything up but haven't had chance to run bike due to work and Northern Irish weather. Will keep u all updated. Cheers

andybaggies · Post by **andybaggies** » 1 year ago

Aussiejoe wrote: ↑1 year ago Sounds like to me that the fuel drain barb is blocked, which also doubles as a fuel tank vent pipe and is causing a vacuum in the fuel tank.

That's a good shout....

Not sure what the sensor is but it has a short moulded pipe. Could be air temperature. 1st thing I noticed was the sensor had come away from mounting so replaced bolt. Assume this should earth to frame.

If it was on the LHS and had only one bolt then yes it is the air temperature sensor. I'm not sure it does earth to the frame though as it screws into a clip in the plastic moulding.