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Discussion Starter #1
He completed the 7.5k mile service, & works on a lot of MV's, but says he's having trouble with the fuel pump,


"wish I could tell you the bike’s all set to go, unfortunately the fuel pump issue is
still not resolved.

I’ve disassembled and double-checked all the work done during the
course of the service, tested the fuel pump and the wiring from the
harness, I’ve checked all connectors, lines and wires relating to fuel
as well the tip over sensor and anything else that might control the
pump. I’ve confirmed the good condition of the battery and as yet do
not see why the fuel pump is not correctly priming.

I will continue on it tomorrow and contact the dealer for insights on
Tuesday if I haven’t figured it out by then, please let me know if you
have any questions and I’ll be in touch as it progresses."
it is the newest sprag design, and i wrote back telling him it typically takes a bunch of cranks to start on the first start of the day. not sure if that's related.
wondering if you guys know anything else, or some MV voodoo, he can check.
 

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What about a fuel filter. Could be clogged. Or bad gas that has gunked up the pump.

Does he have the ability to hook a computer up and isolate just the fuel pump and cycle the pump on and off?

Can you hear it whining when you cycle the key?


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Discussion Starter #3
Just visited him today. You can hear the pump priming when the key is turned on. Then when starting, lots of cranking and no turning over.
He installed a new filter, but plans top put the old one back in and try a stock battery, since mine is lithium now...
the valve check went smooth, all the clearances checked out. but getting it back together has been a headache.
hopefully will get sorted out soon.
 

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Is there fuel pressure to the injector rail.
That is what I would check next,but your mechanic should know that.
 

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Is there fuel pressure to the injector rail.
That is what I would check next,but your mechanic should know that.
True^^^^

Also I would ohm test the injectors. They may be out of range and/or have a clogged hole and need to be cleaned and flow tested. I doubt your injectors are out of ohm spec but it takes 5 seconds per injector and he is already in there. It's more likely they need to be cleaned and flow tested....If they indeed are getting fuel pressure to the rail....if not then check the fuel pressure regulator.

And get a new mechanic lol just kidding but sort of not....


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What did it do before, what did you change and what is it doing now? That should lead you in the right direction.

BTW , the manual calls for removing of a fuse after an oil change , cranking it a few times then replacing the fuse. Think it is the fuse for the fuel pump or ignition. I would check that. Maybe he removed the fuse and forgot to put it back?
 

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Wonder if the hose has popped off the pump inside the tank......

It ran before the valve check, right? And now, on re-assembly, it doesn't?

Happened to me once.... had the tank off for a while, put it back on and no start....hose popped off the pump.
 
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Wonder if the hose has popped off the pump inside the tank......

It ran before the valve check, right? And now, on re-assembly, it doesn't?

Happened to me once.... had the tank off for a while, put it back on and no start....hose popped off the pump.

if the hose is off then you should see a lot of swirling in the tank when the pump is priming
 

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Discussion Starter #12
thanks all. I relayed all your suggestions and they've been eliminated. He called a dealer and they said sounds like a bad sprag! Mind you, this is the same dealer that installed the latest sprag less than 1000 miles ago! and it was performing just fine when I dropped it off for this 7.5k service...
he did the valve check & oil change. Valves were to spec. put it back together. he says the fuel pump shuts off unless the engine is completing rotating during starting process, but it isn't.

damn, if it is a sprag, I'd not gonna be under warranty this time, and it feels like BS since it was working fine, and barely had maybe 700 miles on it.
 

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There is also supposed to be an ECU programming change to enhance starting capability. Make sure the ECU update is done.
 

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Discussion Starter #14
There is also supposed to be an ECU programming change to enhance starting capability. Make sure the ECU update is done.
pretty sure Munroe motors would've done that when they installed the newest sprag version earlier this year, but I'll bring it up. thanks
 

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Discussion Starter #15
well, he tripe checked his work, couldn't find an error. Off to a dealer; Munroe Motors in this case. Ugh... Maybe it does need a 4th sprag?
it wouldn't start, but it didn't make the typical failing sprag noises that i'm VERY familiar with. Just an electrical starter sound and not much else...
 

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When the sprag clutch slips it throws the timing out on the phonic wheel by the ECU counting the wrong number of teeth,so no start until you turn the ignition key off and back on again to re-set the ECU.
But I don't think the sprag is the problem in your case because you would hear the sprag slipping and it has been replaced recently.
Also the motor should at least shows signs of starting after key off then back on.
Did your mechanic check the fuel pressure as we all asked you.
 

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well, he tripe checked his work, couldn't find an error. Off to a dealer; Munroe Motors in this case. Ugh... Maybe it does need a 4th sprag?

it wouldn't start, but it didn't make the typical failing sprag noises that i'm VERY familiar with. Just an electrical starter sound and not much else...
Make sure he checked that the engine, while it is cranking, is turning the engine over at the specified RPM range listed in the service manual. Very important!

As it was told to me by my MV Agusta dealer, if the engine is not spinning at the proper RPM then that means that either your sprag is slipping or your starter is weak.

Did he hook up a computer while cranking the engine to verify cranking RPM?? That is the question. Make him give you a number range to verify he did this.

This is the only real way you will know if your sprag is slipping!

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