Hello! I'd be grateful if anyone has any pointers to this. It seems to be an intermittent fault with the fuel pump. Started bike up couple of days back, got leathers on...then bike stopped and wouldn't refire. No pump priming sound. Pushed it into the garage and this morning had a look, pump primed ok, fired up fine. Weird. After a short while it cut out again and same symptoms... it wouldn't restart..no fuel pump priming on ignition contact. The immobiliser key logo does go out, the bike is in really good nick all electrical systems clean and correct, no error codes displayed. Any ideas - relay first I imagine?? Cheers Grant
hopefully it's something intermittent like a connector or relay as you suggest, or pump itself but can't rule out a line break in the wire(s) that run through the pump body. This seems to happen on 749/999 and Multi around that year more than other bikes. Relay swap would be first for me as fail frequently.
The relay is more or less a consumable on the 749/999 due to the position of it. Always worth a check or swap it. Check also the connector for corrosion.
My first thoughts with these types of problem is always either clogging or irregular fuel pressure . Note - this works best if the tank is below half-full. Open the filler cap and run the engine or at least attempt to start it , and look out for two things 1] fuel squirting out of the supply line to the injectors from a split ( a bad thing ) 2] fuel coming out of the return line ( a good thing ) It doesn't cost anything to have a look .... well possibly your eyesight , if it's option [1] and you aren't wearing safety glasses ....
Thanks for reply Chris, can I just fit any 12v 20A relay? I don't think the one that was on the bike is standard: Apologies if it is a dumb question...electrics are an utter mystery..
Turn it over and have a look at the positions of the spade terminals , and check the numbering on them . Then take it to your local auto-spares place and get a new one , for just a few squid . It's a very common component , and even if it doesn't fix the problem it's always good to have a spare
it's a skinny, half-size unit - I will bring up a link unless someone beats me to it - @chrisw has added an E-bay link several times, and i emulated him also a couple of times. here's one for starters, but they turn up even cheaper - get two! - i have 2 or 3 spare. https://www.ebay.co.uk/itm/2-NEW-Du...MIgue5v7PA8wIVhJiyCh0_KQ2lEAQYAiABEgIBlvD_BwE
4 pin micro relay - https://www.ebay.co.uk/itm/14133799...gyq9EtCRF2&var=&widget_ver=artemis&media=COPY Relocate the relay to the top left of the battery box. You will find a square rubber holder there to take the relay. This makes replacement a quick job. Also check the wires to the tank that pass between the vertical cylinder and the tank. These can chafe and cause a short circuit causing the fuel pump to not prime.
I have exactly the same issue with my 749. Initially thought it was the battery but given the intermittent nature of it i think its either fuel, a blockage or the relay I have just got my new relay so will have a play this weekend The fuel has been sat in the tank for ages so thats likely not helping either i never thought about the wires chafing so will check those puppies out too this is the relay i bought https://www.ebay.co.uk/itm/314968057612
It may be the fuel pump loom. I had this on my 749 - took me a long time to diagnose. Luckily, I have another 749 so I swapped the tanks and the one with the issue was cured. I had to get a new fuel pump sub loom from Stein Dinse. I posted the issue back when it happened a few years back - have a search.
Thanks for the suggestions everyone...purchased a new relay.. no change. So broke out the multimeter and checked both continuity on the -ve wires and then voltage on the +ve working from fuse to relay to connector under the tank...all seemed ok...bollox. Tis funny it wasn't complicated with the wiring diag in hand, but overcoming the mental block about electrics was more the issue! Drained tank and removed pump assembly...voltages seem to be ok all the way to the pump... A good thing to note (for the next sufferer!) is that the pump receives 12v only briefly on the initial key turn...the ECU recognises that the lines have pressure and the voltage drops... edit as per Duke of Stow's post: ...runs the pump for a certain number of seconds at key turn... so the voltmeter has to be connected prior to key turn. All good for voltages, so next was to directly connect the pump to a battery. Ah ha...nothing, bollox this risks to be expensive. So gave the pump a damn good tap with a screwdriver handle...and that's all it needed. I swear she was just laughing at me...I told her if she carries on like that she'll be sold...so we'll see how she reacts.
Did you wiggle the wires when measuring continuity to the pump? Just saying as it would be a pity if you have an intermittent wire discontinuity that reveals itself again once the pump and tank are reinstalled.
It's still not resolved for sure...I put tank back on...pump primes ok on key turn...started up fine...then after maybe a minute the bike stops and symptoms are the same...no fuel prime. I just can't see this being a wire break, everything is too new and clean and the bike was stationary for a while prior to the first time the issue presented itself. Am I looking at a new pump? ps: going to have to press pause on this, the outside temp has just plummeted...back to it tomorrow.
Just so you know, the pump prime is just a timer, the ECU does not have a fuel pressure sensor. The pump and coil power cuts back in when the ECU sees the crank trigger and it hits minimum revs for starting. The brown/white wire is the switched feed from the relay. The ECU switches the -ve side of the relay coil to energise the relay, and this is easily checked with a multimeter. Don’t rule out the crank trigger failing as a cause.
Thanks for this Ricky, I've re-stripped everything down again and really closely checked each and every wire. Seems I have exactly the same failure as yours. The black pump wire appears to be breaking down as it enters the silver sealing cylinder on the pump support plate. You can see the brown sealing material degrading. Cheers Grant
Common problem, you can carefully dig out the epoxy and repair the wire before repotting. I have contacted the original supplier in the past, they will sell them, but want a minimum order of 100
