Anyone any ideas what's up with my 748s , as you can see and hear it's not priming and not starting then all of a sudden it primes and starts but sometimes it primes but still doesn't start , any ideas as this is going on to long
Dave, as your headlight is switching on but the fuel pump is not priming and the starter is not getting energized I would suggest you have a problem with your sidestand safety relay circuit. Start with checking that fuse 8 (RH switchgear) is seated properly. Then you need to check the operation of the safety relay and sidestand switch by raising and lowering the stand with the ignition on and the bike in gear. If necessary remove the sidestand switch and make sure that the two pins are not damaged and the switch is rotating properly, spray it with contact cleaner. Then you need to check the safety relay itself. The safety relay is one of the group of four down by the bottom left side of the battery. Separate the two smaller black relays from their connectors and check the undersides for signs of overheating. From memory the fan and safety relays are interchangeable so you can swap them. Whilst you are there check that the yellow one (main engine relay) is clean and sound and has no signs of overheating. If problem still persists check the wiring connectors on the side stand switch and the security of the connector for the RH switchgear in the headstock area. Also spray some contact cleaner into the RH switchgear, you may need to undo the two screws which clamp this onto the clip on. Good advice is to not start the bike with the headlight on as it really does not help to have that current draw when the bike is being started and it stresses the bulb/HID system unnecessarily . My money is on the sidestand switch then the relay btw
Cheers Denzil I've got this problem for a long time now , I have the side stand switch disconnected a few years now but I'll have a look at it and I'll also have a look at all the connectors . I've checked the 2 fuses under the seat and switched them around and I cleaned some connectors but it's still the same , I'm gonna give it a look over the weekend . Cheers
Can be so many things and as Denzil has said the relay under the seat certainly fits the symptoms. Lets see if the relay swap works before adding more suggestions.
get multimeter on pump connections Leave connected insert paper clips carefully in to back of plug are you getting power. if you are. new pump.
If it is the relays you've checked have a look for a couple of fuses under the seat as well, one of them is for the fuel pump and they can get very hot and start to melt if any corrosion is present causing problems.
. yeah I've checked them as well and all looks ok and I've took apart the engine off switch and sprayed it with cleaner but that looked ok ( must check the connector block ) and I've checked the ignition connector block and that was dirty so I cleaned that but still the same
The fuel pump fuse holder under the seat melted on my 916, the fuse and holder sort of became one sticky, black, snot-like lump - was actually still working but wouldn't have done for long. I also had an intermittent main relay (yellow relay near battery) that would prevent it starting sometimes.
Dave, I think you misunderstood my post. Looking at your video your starter button and the fuel pump are not energizing reliably and the most likely problem is one that can be implicated in both faults (if there is only one fault) and that is the RH switchgear/safety relay supply circuit. There is another possible fault which is a dodgy yellow relay but if that was a problem you would get no lights when the ignition was on. The RH switchgear circuit works like this; when the ignition is turned on the main yellow ignition relay switches +12v to the fuse box (under RHS fairing) and through fuse 8 (3A Marked "RH Switch") to the sidestand switch. If the sidestand switch is set correctly and the bike is in neutral (green light on) it energizes the safety relay coil (down by the battery ) which switches +12v to the engine run button. If that switch is in the run position, current is allowed to the starter button and to the under seat area through the orange and blue wire to energize the fuel pump relay coil which switches the fuel pump supply on. You say you have the sidestand switch removed but this will only work if you put a link in the sidestand loom connector to replicate the switch or link out the safety relay plug pins 30 and 87, the latter short circuits the entire sidestand and safety relay circuit meaning the safety relay can be omitted. If you have a link in the loom for the sidestand switch that is the first place you need to look. There are other possible problems which could be due to poor contacts on pin U of the main wiring loom connector under the front of the tank or a loss of cable continuity (broken wire)in the loom somewhere. BTW swapping the 20A fuel pump fuse with the 5A ECU fuse under the seat is not likely to correct the problem and I recommend making sure you have the correct fuse in those two fuse holders as the fuel pump is likely to blow a 5A fuse and the ecu does not get the protection it needs with a 20A fuse. Just to be sure the safety relay is not under the seat it is by the battery, also a fault on either relay or fuse under the seat will not result in the starter button failing to work. Let us know how it goes when you start playing but try to work out how it works before you start pulling stuff apart, it is quicker that way.
