Hi all, was out for a run on Friday (day before getting the ferry for the North West) and the 996 decided to breakdown. Luckily my 916 monster was called into last minute service and the trip went ahead as planned. Back home now and having and trying to work out what the problem is. Bike was running perfectly on Friday, stopped after a 50 mile run to fuel up. Brimmed with E5 and about 2 miles later the bike just stopped. It felt like the kill switch had been flipped. Managed to coast to a halt at the side of the road. All electrics working fine and engine freely turning over. No coughs or splutters, just turned over without catching. Anyway breakdown service gave me a lift home. I’ve checked all fuses and OK. Whipped out the plugs and they are bone dry and a good colour. Oddly no smell of fuel though…..I can hear the pump priming. So tank off and check the hoses. The fuel breather is split and it’s not forming an air tight seal. Could this be the issue? Any other suggestions. Bikes has been faultless so far in 2 years of ownership.
Not a fuse if you can hear the fuel pump prime. Quite possibly a split hose on the fuel pump inside the tank. You may be able to see if you open the cap on the tank, fuel swirls about inside when it primes
So the breather hose split has nothing to do with it? I’ll get a replacement anyway. I’ll also double check the relays and then have a delve into the tank itself. I’d there not some venting that takes place from the fuel filler cap itself, it does seem to be fuel starvation related.
That pipe that comes from the bottom of the tank is just to allow overfilling the tank to bypass the hot engine and drip fuel on to the ground.
i'm sorry if this puts the cat among the pigeons, but never had a perished/split fuel pump supply hose inside the tank with the above symptoms. While it's true total detachment of the hose might fit in with the above, symptoms normally starts with engine not wanting to pick up from lower revs, but will still idle and at the very least you'll still get a cough on churning when trying to start. if it were me I would pursue electric first although with fuel pump priming it doesn't sound straightforward.
Not if the starter is turning and the fuel pump is priming. Even if the SS switch failed, the bike should start in neutral. Pick-up connector?
Do you have the original plastic, quick-release fittings on the fuel pump/tank base? You could try 'cycling' the pump (ignition on) with the return fuel line (R) disconnected, if you then push the spring-loaded end of the fitting in whilst pressurised it will leak/spray fuel out the end, obviously be careful if doing this.
had this on my 916, could ride down the motorway and it would die, kill switch on and off it would go again. replaced under sear fuel relays been perfect ever since.
Also linked to the breather (by the 'Y' connector) so can cause running problems if it is blocked but, as above not if not connected.
although a distant cousin of the first I.C. engine, the basic tests remain the same - with a slave (spare) spark plug attached to front coil lead and resting on cylinder head to earth out, in preferably a sun-shaded location, have you got a spark when you churn the starter with ignition on?
Bit of an up-date….tank back on and double checked all fuses/relays. The pump is defo working, with the cap open you can hear it and see the fuel moving inside the tank. The 2 relays under the seat - relay on the right is clicking, the one on the left does nothing when you switch the ignition on, is this supposed to be the case. Swapped them over and the same result. Probably turned the bike over a dozen times today, sometimes on full throttle. Whipped the front plug out and it’s still bone dry and doesn’t even smell of fuel. So I’m pretty sure that petrol is not getting through.
Thanks for all the replies so far It took 2 or 3 years to get my S4 monster sorted, I guess this is all part of the ownership experience!
About the two relays: one is for the fuel pump, as you know, the other for the fan. So unless the engine temp is high enough, it shouldn’t trigger. Nothing wrong. I too think there must be some kind of internal fuel leak inside the tank. Not necessarily a split hose. It could also be a porous one. Have you removed the fuel pump assembly to check things out? Here’s what I found in my first 916 tank shortly after buying it. I found out when it left me stranded by the roadside with what felt like I ran out of gas, except the tank was half full…
Cheers, I’ve not delved into the tank as yet and that puts my mind at rest re the relay. Looking through old service records I don’t think the fuel filter has ever been changed either. Looks like this will be my next port of call. Will update when done……. Thanks again
