Rattling From Inside Petrol Tank

Whilst working on my 1200 Speedmaster today I noticed after bumping into the bike a knocking noise continuing for a few seconds. I narrowed this down to the left side of the petrol tank, the side the fuel pump is on. The tank is a quarter full and the noise continues after the bike stops wobbling so it's definitely something floating on, or been knocked about by, the petrol. I'm guessing it shouldn't be doing this?!

 

So, my 20,000 mile service a few weeks ago should have replaced the fuel filter. On the checklist they marked it as N/A, on querying this, they looked at the parts diagram and acknowledged it did have one but the service kit they got didn't included the part. So they agreed to order the filter and get back to me about arranging to fit it. (I haven't heard anything yet).

I've just looked online, and the service kit they charged me for (part T3990166) does include the fuel filter. So I'll be ringing them tomorrow to chase this up. If there's anything loose they'll find it when changing filter.

Could just be I'm worrying unnecessarily, there's an awful lot of gubbins in the tank, from photos in Haynes manual, it's not obvious that it's particularly fixed in a rigid place. Perhaps it does slide around if you slosh a quarter of a tank of fuel around? (Not noticed this before though in 2 years of ownership)

Edit: From parts diagram it looks like there is a bracket to hold everything rigid, and looks awfully like older models featured in this YouTube vid so have ordered cheapo endoscope to try and take a peek tomorrow.

 

Not at the moment as the fuel cap is on the right, and the rattle on the left, and the tank sorta wraps around the frame, so with only a 1/4 of a tank of fuel, its sorta split in two halves. (Though obvious actually connect at the back)

It's not the first time I wished I could peek into dark places, so consider it a good investment. (Though perhaps I went a bit too cheap and nasty with my purchase, lets see tomorrow).

 

Hmm. Well, it's 5V as it's USB. If it's in the fuel that's OK, because there's no oxygen in the fuel for it to combust with It's the air and fuel vapour mix above the fuel that's flammable . Can't see any reason beyond weird catastrophic failure why a USB camera should create a spark between it's own electronics (bike isn't part of it's circuit), But getting it in the petrol is a distinct possibility and it's supposed waterproofness might not count much for that, Hmm, I'm now thinking twice about this, thanks for making me stop and think.

 

Thought did occur to me, but I couldn't see a float on the parts diagram, so assumed it was some sort of pressure based level detection. However, double checking there's a 'Fuel Level Sensor' on a different parts diagram that looks awfully like it has a float (difficult to tell from the diagram). This is where my face might start to redden in embarrassment.

 

So, I have just filled the tank in effort to float whatever is in there near the filler hole but after various jiggling can't spot anything. Also, it's not obvious the rattling is still there, I may now just be noticing fuel sloshing noises. It seems a possibility, that before I may have just been hearing a fuel level sensor float. (When I went to fill up, the fuel gauge showed I actually had only 1/8th of a tank, so float would have been very near bottom of tank when I heard the noises.)

As the bike runs OK and the dealer is due to have tank apart to replace the fuel filter they missed out on service, I think I'll try and stop worrying and let them find out if there's any problem.

In case you hadn't noticed, I'm a perennial worrier! But in my defence I've had 8 genuine problems with bike in the 2 years I had it from new, 2 of which where other peoples human error during maintenance, and one probably mine.

 

So, bike been in to dealers today to have the fuel filter change that wasn't done at service time. Technician didn't find anything in tank or anything else untoward. Reckoned the noise I was hearing might be electrical cables and plastic connectors that connect to the fuel level sensor. Apparently these just dangle a bit free in the tank. Must say, when I got to dealers, with a 1/4 tank of fuel, I couldn't hear anything rattling. What I heard at the weekend could just be the unusual circumstance of 1/8th of a tank of fuel with the bike upright on rear paddock stand, so what little fuel there was would have been down front of tank. One day, I may try and replicate that.

 

No, I didn't conclusively find out what was making the noise. It's now 15,000 miles later and still does it, so I guess it's nothing to worry about