Ok, The last mechanic to work on my M750 said that the fuel pump needs to be replaced and that I could do it myself. Im trying to find some kind of instruction online but its not working out so well. Can anyone point me in the right direction? Thanks! -Rod
(I've cleaned the carbs, took the air intake back to stock and tried to get the fuel/air ratio right but its still bogs down. top speed 80mph DOWN HILL)
The fuel pump, if OEM, is a mechanical, hexagon shaped external pump. Carefully pinch off fuel line from tank, remove fuel hoses, remove the two bolts holding it to the frame. Your problem is probably not the pump though. Did you buy the bike running like that? What is your jetting? Float height? What condition are the diaphragms in?
+1 On Howie's suggestions. A carburettor overhaul is not unreasonable for an older bike.
And does the bike still have the vacuum fuel tap? When they fail, they can either leak and flood your motor or not open correctly (or at all). They can restrict fuel flow when beginning to fail.
What color are the spark plugs? They can tell a lot about what may or may not be wrong.
You can test the pump and tap by bypassing them one at a time and seeing how the bike runs. The Fuel tap should pass fuel into a bucket when the motor cranks (careful of sparks, etc when doing that). Vacuum line opens a diaphragm (which can fail). Check the lines from the tap and pump to the manifolds. Pinched, perished, leaking?
Also worth checking the air and fuel filters.
Are there any mods to the bike we should know about? Did it previously have an open airbox or pods?
Hopefully the bike may just need a full service and a few extra items to be happy.
If you test the pump, the tank has to be more than a 1/3rd full, maybe over half to feed the carbs on the "uphill" fuel line.
Oh and welcome to the forum. Introduce yourself in that section. Cheers.
Do check the diaphragms, they can impact throttle response quite a bit. I had to replace mine on my M750 at around 30,000 miles. They had fine cracks that weren't visible until you looked at them with a decent light behind them. If you find them suspect, they are expensive from Ducati, and you can't get just the diaphragm, it's the whole diaphragm & slide assembly. I used diaphragms from a DR650 and it was a quarter of the cost as buying from Ducati.
JM
Ive seen good diaphrams not seated correctly causing a lack of acceleration as the CV piston refuses to rise. Worth checking that the little o-ring on the air port hole hasnt fallen out if dissassembled at some time.
If you do find the pump the culprit, carbparts.com sells a rebuild kit MK-DF62 that'll fix it right up. I think it was about $25. The kit's for a double pumper but since ours is a single it's like getting 2 kits in one. Comes with diaphragms, gaskets and check valves. I rebuilt mine shortly after I got my bike and it needed it. The plastic diaphragms were all warped up from either old gas or ethanol.