Intermittent problem - Engine wont idle, smell of fuel - FPC on its way out?

[Martyn B]

Anyone care to diagnose the above issue?

It started weekend before last when I was stuck in traffic on the M5, unable to filter coz of narrow lanes. The engine got very hot and eventually I stalled it after which it refused to start and the battery gave up the ghost (thats on its last legs as well). I was lucky in that I was on a downhill section so I got it into the roadworks which are in the central reservation and managed to bump-start it. All seemed well after that and I completed a 150 mile journey without further issue except for I noticed a reluctance to run evenly at low revs.

Two days later in the pouring rain of Sunday 10th August, it started to cut out when coming to a halt at road junctions etc. I managed to get it started again but I needed to keep the revs above 2k or it would just die. I put this down to the rain at the time as it was another 150 mile sub-aqua trip. The next day I started it and it still wouldn't tick over so I took it out to test ride it but it cleared itself within the first two miles - perfect. Since then I've covered another three or four hundred miles with the problem recurring on each ride but not staying in one state for the whole journey. When it cuts out there is a strong smell of fuel (no, the fuel tank is shut ). It's managable but doesn't make for relaxed riding!

I had an FPC go on me with my previous GS (the single cam version - who didn't have a problem!) but that was a very obvious dead bike - not like this at all.

So FPC or something else?

 

[Martyn H]

The only time I've had a strong smell of fuel ( it was on my 1150R ) it was the plastic fuel connects disintegrating. Once replaced with metal ones (brass I think ) no further smell of petrol.

 

[Deleted account 190920001]

Doubt it is the FPC as you would have no fuel instead of too much. Check for leaks (probably already done) and check your ignition. Pull the plugs and see what they look like along with checking your coils.

 

[Martyn B]

Hi Martyn, thanks for replying - hows tricks? I've checked the lines (just a casual inspection) and there's no sign of any leaks or breaks. Just waiting for Cotswolds Motorrad to ring me back now...

 

[Martyn B]

Doubt it is the FPC as you would have no fuel instead of too much. Check for leaks (probably already done) and check your ignition. Pull the plugs and see what they look like along with checking your coils.

Thanks Marki - yup, guess thats the next step. Time to get the hands dirty

 

[Schtum]

It's notoriously difficult to diagnose these things via the Internet. However, when this happened to my '07 bike, it was a failed lambda sensor. The bike will run fine at higher revs but when you throttle off and the bike should run in closed-loop mode, the faulty sensor won't maintain a correct mixture and the engine conks out.

 

[Martyn B]

... failed lambda sensor. The bike will run fine at higher revs but when you throttle off and the bike should run in closed-loop mode, the faulty sensor won't maintain a correct mixture and the engine conks out.

Well, thats exactly what happens - but if it is, I'm suprised that its intermittent as normally the sensor works or it doesn't...

Again, thanks for the input

 

[Bendy toy]

Mine did this and I replaced a Lambda which was sooty black and not working. The real cause was both coils failing intermittently. One was only slightly worse than the other making it very hard to diagnose by swapping left to right.