symptoms of fuel pump needing rebuild? M750

[motoxmann]

as the title says, what are the symptoms of a fuel pump in need of a rebuild?

I have no clue when the pump was last rebuilt. I did disassemble it to clean it out and inspect the parts inside, and they all looked well to my untrained eye as there were no tears in the membrane and the valve things sealed perfectly. I've never had any bogging or misfire issues, but I have been chasing a weakish top end issue to no avail, and if memory serves me correctly the membrane may have been deformed, and looking at pics of the rebuild kits the new membranes are dead flat whereas mine I think was slightly bubbled. thoughts?

[koko64]

If the top end power is lacking fuel and not responding to jetting, then for the low cost of a rebuild kit, I would do it as a precaution. You dynoed the bike?

[motoxmann]

I have not dynoed the bike yet, but it seems to slowly be losing higher rpm power, pretty much anything above 6500rpm seems to be slowly tapering lower and lower. engine is freshly rebuilt (2100 miles since rebuild) and all mechanical aspects of it are perfect. coils test well, several types of plugs have made no change, charging system is perfect, ignition system is perfect and timed at stock spec, have tried multiple jetting combinations and the current setup seems best for the current weather (45 pilot, 140 main, FP springs, DJ needles on middle notch, nickel plated tubes, 1.75 turns out, 14mm float height), valves within assembly spec, fuel filter and fuel screen are brand new, fuel hoses are all perfect, vacuum petcock is removed, ground points are freshly sanded, negligible voltage drops across high current power and grounds wires, etc etc

I've been a car tuner for almost a decade now and have plenty of wideband stuff. I'm thinking of welding a bung to one of the pipes after the crossover and installing a digi readout wideband. just need to get it welded up as I don't have a welder anymore

[motoxmann]

also, where do you guys recommend buying a rebuild kit from? the only decent one I've found so far is:
http://www.jetsrus.com/individual_parts/002_226_su.html

[koko64]

I thought SUDCO had the Mikuni kit? DP knows who has.

What kind of filter? I had one of those bronze porous  element filters (Speco) and it gummed up on modern fuels restricting fuel to a trickle. I cleaned it with carb cleaner and it barely flowed a drop under gravity. The medium was so fine it was glued shut with the fuel detergents/waxes added to clean injectors under high pressure. Thats a long shot and down here though. I'm now running a Visu 601 (made in USA).

Sounds like its worth rebuilding the pump for sure.

[ducpainter]

Pretty sure SUDCO does have the rebuild kit.

I tried to download their catalog to confirm, but it locked up FF.

Give them a call.

I'd try a different filter, and check the small screen where the fuel line enters the carbs before I rebuilt anything

[Howie]

Sudco has them.  The kit will be listed for a two outlet pentagon pump.  Same kit. 

The diaphragms are starting to go from your description, so you may as well rebuild. 

[motoxmann]

I use napa fuel filters, I forget the number but it's the exact replica of the genuine ducati one and it flows like niagra falls haha. the fuel screen at the carb inlet is brand new (genuine ducati). I've checked it a few times too and it was always clean as a whistle

[ducpainter]

Check flow at the pump. Typically any shut off is downstream of the filter.

If it's sufficient it's time to rebuild.

[motoxmann]

definitely will do. just ordered a rebuild kit anyway. it's cheap enough and I'm sure it couldn't hurt.