[Yorik]

Go through the checklist. You need air, fuel, and spark. Start with the easy stuff. Check the air filter and inlets for blockage. Check that the plugs are working as they should. Swap the two relays under the seat around and see if you might have a bad injection relay.

 

[belter]

when it stops and won't restart:

is there normal electrical power to dash, etc?
does the fuel pump run at key on?
does it crank?
does the fuel pump run while it cranks?

 

[BOTT]

Check and see what the battery reads right now. Across the battery posts read 12.8v being Ideal sitting for days. 12.6v and below, battery needs a charge. Battery is how old? Battery was charged during it sitting?

 

[Warwick1960]

Thanks guys, Plugs replaced and air filter too with service. Relay replaced along with the fuel pump. When the bike goes it’s great......it’s the intermittent problem that’s the worry When not starting normal power to the dash....It cranks fine and I think there’s power to the fuel pump. I have replaced the battery as well

 

[BOTT]

"I have replaced the battery as well" and the battery reads right now is?

 

[belter]

I think there’s power to the fuel pump.

don't think. find out if there is or not.

 

[kwick5]

Might be the Crank Position Sensor. Read the 4th post on this thread as most have different characteristics, but yours sounds like this. Crank position sensor error

 

[Stillrollinalong]

You said fuel pump was replaced, did you replace fuel lines?

 

[Warwick1960]

Thanks a heap guys,
Belter, I now know that the fuel pump is working.... I hear it every time I crank it over. That could have been the problem.
Following the crank position sensor feed, it sounds exactly what I’m experiencing
Will check it out
Regards everyone

 

[Warwick1960]

Fuel lines are in good shape apparently as they were inspected when the pump was replaced.
I rang a stealership and they said that bikes of my era don’t necessarily throw up codes
Anyone have the same problem?

 

[stoshmonster]

Anyone have the same problem?

Yeah I had something similar happen on my '95 900SS Warwick. Bike would just stall for no apparent reason and refuse to start. Wait maybe 15-20 minutes and the bike would fire up no problem.
One day after the bike stalled I opened the gas cap and heard a loud whoosh of in rushing air. Hit the key and the bike fired right up.
Turned out that the oneway inline check valve in my fuel tank breather hose was sticking and causing a vacuum to build up inside my fuel tank that was starving the carbs of fuel.
A pinched or collapsed tank breather hose or a clogged tank breather system will cause the same issue.