I did a big tank internal cleanout recently, changed the fuel filter and checked all the pipes and tubing. Put 8 litres of fuel in, turned on the ignition, heard the pump whirring as usual.
When it came to startup time it took a bit of cranking to fire then it sounded and felt like shyte so I switched it off straight away, checked the plug leads and things and tried again. It fired straight away but only on one cylinder. I gave it a bit of throttle and the second cyl began to chime in occasionally. It needed a good VAROOMAH VAROOM but it was kinda late, my neighbours are quite tolerant of motorcycles arriving or taking off at any hour but driveway tuneups after midnight would draw comments.
So headed off for a quick test ride, chugged and fluffed down my street, and once on the main road it still wasn't happy at all, must be an air bubble in the works I thort. Gave it a real handful in 3rd and after an initial big stumble with backfires and popping it lit up, and seemed to be more willing to rev than ever before. Ran it up and down the rev range and all was sweet so straight back home and quietly into the shed
Now, point of story, in the 3 years I've had this 'bike there's two minor glitches I've just put up with as I know little about FI . The idling was rough and too fast for my likes. I tried to slow it down with the simple throttle stop screw but it got rougher. Secondly, a flat spot just as it comes off idle meant a bit of a lag after opening the throttle then a sudden jump to 2,500 rpm or more. No big deal - when taking off from a stop I had to wait a couple of milliseconds for the motor to wake up and slip the clutch a bit more than I'd like, same as riding an old British single :-) or hooning.
Today went for a decent ride, including inner 'burbs, and noticed the flat spot has gone, and the idling sounds sweet, nice and even.
Question - unlikely a fuel filter change would fix the flat spot and rough idling. Perhaps getting an air bubble in the hoses followed by some very heavy handed twistgrip activity does good things to the injectors ?? I'm thinking maybe an air lock lets the pressure build up then an explosive air release followed by a hydraulic hammer sorta knocks a bit of sense into the injectors.......
I'm thinking the dirty filter was more likely the problem than the throttle tuning the solution.
I could be wrong.
Dirty fuel filters will cause all the nasty symptoms you describe
Using the throttle to clear a driveability issue is classically known as the italian tune up.
Sounds to me that the filter could definatley cause these symptoms. On another post recently I said that my tank had some nasty shit in it. My bike was showing symptoms exactly like you describe. Turns out the nasty shit was rust sealer (appears to be done as a preventitive measure) and clogged my fuel pump sock and the fuel filter. still waiting on the sock from duc, but a bit of injector cleaner in the tank has cleared it up very well.
Could have been a pinched hose after you put the tank back on, that then came free.
>> Could have been a pinched hose after you put the tank back on, that then came free.
Not a kinked hose, but yes, that's a poxy system under there and worth a careful check when putting the tank back on.
As seems to be the custom around here I dissected the old filter. Inside the alloy body is a pleated paper shaped into a tube. The inside of the body and outsides of the paper were covered in light brown powdery stuff. No lumps, looked like the finest powder that builds up in a coffee mill.
When I cleaned out the tank there was a tiny bit of rust around where the metal pipes enter, and some ? chaff or other vegetable matter down the bottom and stuck on the mesh sieve.
Presumably the pump churns whatever comes thru the sieve into powder. When I had the pump in my hand I was wondering if it needed a bit of TLC but it looked a bit too well put together to accept any fiddling.
Could it be a good idea to put a filter on the inlet side of the pump, replacing the sieve? I mean a big one so as no to mess up the pressures/flow, there's plenny room in there.
Quote from: csp808 on October 16, 2009, 07:39:09 PM
Using the throttle to clear a driveability issue is classically known as the italian tune up.
Ditto... that's more or less how I keep my Alfa in shape :-D
I missed it in the write up. How exactly does reference to Mexican fit in this? ???