Hi all, Its that time again to pick the brains of the genius forum members. As with most my 2003 749 had sat mostly idle for the year. It was started at times and little run around but not much. As the major service was due I had the belts, valves, fluids etc all done by a great duc workshop in the uk. He found the valves were way out (probably never done) and it pulled like a train but had a strange stutter and hesitation. But we decided to leave the dyno test until later on in the year. Since trying to ride the bike a couple of times it now won't start, it cranks and sometimes sounds like it will fire but then sounds like it has locked up. I suspect this is a bad battery not providing enough amps to the starter after I neglected it for a year. However, half way on a 100mile journey and starting the bike after a coffee stop I had a strange very loud clattering sound as well as the fuel pump prime. It did start and after turning off and on again the sound hasn't reappeared. Since then the bike slower stuttered more and also the idle has become irratic between 1200 and 2500 regardless of temp or fuel level. During the service the mechanic spotted the signs of the stutter and investigated the below. 'So I spent a whole day playing with your bike , this is what I found ... The rear manifold runs to cold, front is spot on.... This started a day of digging, compression test and, front was 160-170....155 on rear.... so rear rings or bore is worn? This is not alarming, but should be considered. But it’s was still running cold on rear head, so one by one I swapped front with rear parts to see if I could find what wasn’t right.... first plugs, then coil sticks, then injectors.... after ever swap it still was the same??? The rear injector looks like it’s not as powerful as front, even after swap, this can only be electronic as it works fine in front (ps hoses swapped as well) ... This was also verified by upping and dropping fuel map on ecu, along with CO measuring at the same time..... air bypass screws were tested in min/ Max positions as well as electronic throttle body set up all at the same time!!! '.... He is happy to have it back but since I did the work to sell and there is a wait list to get it back in I would like to save his time and cost in diagnosis if possible. I will try and upload some videos when I work out how. I guess it's either the fuel pump, the fuel pump relay or the whole assembly but would really appreciate your help.
The fuel pump relay is a 2 quid part, so start with that. A PIA to get at, though, in the battery box.
Thanks pal, I have seen wiring and pumps sold individually are these just ways to rebuild instead of buying the whole pump assembly units?.
Link to the cranking, to be fair the battery was drained after many attempts. Are the pops from the air box usual?. https://youtube.com/shorts/TAmq72XG1LA?feature=share
There are posts on the forum where fuel pumps have been rebuilt with commercially available kits. There are also posts on how to repair the wires into the pump. Are you able to get the pump out and bench test it?
Probably, I don't have a garage so as long as its dry and light out I can pull the bike apart. Any idea where I can find the spex for the fuel pump relay?. Would be nice to buy one before I take the old one out.
In the YouTube video, I didn't hear the fuel pump prime. Could be the relay, but most likely the wiring in the bulkhead through the tank. I fixed this last summer on my bike. The two black wires didn't appear to have ever been soldered. In your first video it sounds like the furl pump was trying to prime, but was making a terrible buzzing sound. Not sure what that was.
