Hi chaps, I'm hoping someone can help me. I've got a 2002 M750 ie. And it's been sitting in the garage for the last 8 years.. the last 5 or so I've 'forgot' to start it regularily.. cough. I've emptied, cleaned tank, new battery but it's not starting. If I spray some carb cleaner down the throttle bodies it will start up for a couple of seconds then stops and won't start again. The fact it will run for a few seconds with carb cleaner is promising - clearly spark ok, engine generally ok, etc - so it's a fuel delivery issue. I've investigated the fuel delivery by checking fuel pipes are clear, and removing each injector and checking it fires if 12v across it (with fuel filled pipe held above it). On the tank there is an outlet and return, and sort of weirdly (?) with the pipes off, its the return fuel pours out of, but maybe that's expected if the outlet has an internal filter, etc ? certainly if I connect a bit of pipe to the outlet and suck on it, I can hear a 'click' from inside the tank and I get a bit of petrol in my mouth. So, where it's leading me is to thing something is wrong with the fuel pressure valve: https://oem-parts.hu/en/parts/ducati/2002/750/throttle-body-intake-carburettor called '19 holder, rectifier' in diagram for some reason. As I understand it, the tube not connected is to equalise with atmospheric pressure - so I can't really understand how this works ? Is it something like the injectors fire, 'sucking' fuel through it, which opens it while keeping a slight negative pressure which the injectors need to work ? I've established that fuel only comes out the fuel tank outlet if it gets suction, so there's no gravity fuel pressure on the input side of the that valve - so it must be the outlet side which goes to the injectors that 'generates' suction, opens the valve and sucks fuel out the tank right ? But I don't really so how that could work - since the fuel on the return just comes out, filling the hoses with fuel up to the valve anyway - so any fuel the injectors needs it can get from the outlet of the tank ?? When I look down the throttle bodies and turn it over I can see only a few specs of fuel emitting from the injectors - which is what I found when I tested them: then, only when I put my finger over the end of the fuel filled hose I'd connected to them - then they sprayed fuel out as expected - so I assumed they only work if there is a lower pressure on the fuel supplying them ? Anyway, is it possible something is wrong with that, and that is causing the issue ? Can you think of a test I can perform to prove it ? I also tried just gravity feeding the input fuel hose with a funnel of fuel, and that didn't work. So theres obviously something fancy that pressure valve thing is doing what with their being no fuel pump at all. As you can see from above, I've tried to approach this logically, but also from the standpoint of someone who knows utterly nothing about how these engines work - so it is very likely I have got not only the wrong end of the stick, but entirely the wrong stick. Any help anyone can provide to help trace the issue would be appreciated. stu
I suspect the fuel pump has seized, which is a very common problem resulting from a long ‘rest’. Can you hear the pump prime when you switch the ignition on?
is the pump inside the tank then ? there' nothing else in the fuel loop that could be a pump is what confuses me. I know the carb models have a fuel pump, but couldn't see one at all on my bike or the diagram above. I can hear something doing something when the ignition is turned on yes. But I suppose that's no guarantee it works. It's in the tank, how on earth do you get at it ?
The pump is inside the tank. Item 2 in this diagram. Item 12, the fuel filter, would be best changed as well. Access is through the filler assembly which has to be removed and will almost certainly need a new rubber seal before refitting. The filler assembly is held in by a number if small grub screws. After they are unscrewed a a few turns it can be pulled out. The seal is number in the diagram 21 below and it is usually a bugger to get it all back together again.
aha. thanks that makes sense. also, the cable to the tank is getting warm - which mihght make sense if pump was seized. can i ask where you got the diagram ? I could do with finding the part numbers for all the bits.
You are a star.. Filter and pump out. Those rubber pipes perished too. Bosch pump. Definately seized. Apply 12v and nowt happens other than leads getting warm. Is there a preferred source online UK for these sorts of parts? Thinking that I just source a bosch pump it prob won't come with that filter bag thing, and that's falling apart too.
ah, got it. https://www.bike-parts-ducati.com/d..._750_IE/Monster-750-IE/FUEL-SYSTEM/96/40/0/96 looks like will have to be ducati for most bits, but not the pump! 190 quid there, and 50 quid online elsewhere. no price for the fuel filter bag thing though.. wonder if that's discontinued...
The prices from Ducati are £189.59 for the pump and a £23.48 for a filter. I can't find a price from the mesh pre-filter. There is one listed for an M600 up to 2007 here, complete with the pre-filter for £53.36. Or you can take your chance on eBay. Mahle KL145 from Opie Oils for £16.50
thanks - I ended up getting bosch pump and can filter from onlinecarparts.co.uk, a pump filter bag from ebay, and 8mm ID nitrile hose and some SS clips from ebay. should have everything I need.
