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Discussion Starter #1
2015 TV, has always been a slow starter (a few cranks before fuel delivery governed by the CPU, with latest dealer update). However, increasingly I'm having to crank her for a long time, to the point that the battery begins to wane after a minute or two of intermittent cranking bursts.

My initial thought was spag clutch, but the engine is definitely turning over, so I'm assuming sprag engaged.

Then I thought fuel starvation, as I noticed the rush of air intake when opening the fuel filler cap.

Also, I nearly always hear the fuel pump prime for a few seconds, even when the engine/ignition is turned off and then immediately back on again.

I've left the fuel cap open (to prevent the vacuum), and still no difference.

The only time the bike seems to start on the 2nd or 3rd revolution of the crank (as it should), is when I don't hear the fuel pump priming, but don't know why the pump sometimes doesn't kick in, which suggests fuel delivery is good at the time, but no rhyme or reason why sometimes it primes and sometimes not. I've even tried different mapping (Sport, touring, rain).

She's been regularly serviced, new plugs etc. and the battery seems good (as it does last a while with all the cranking), and eventually fire up.

Sometimes, you can hear her trying to fire, until eventually she does, and then purrs without any misfire and runs fine.

Any suggestions of a remedy would be gratefully received.
 

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Think you will find it is the sprag mate, will turn over fine but takes ages to start=sprag
 

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Discussion Starter #3
Thanks for the quick response 👍. My understanding of the sprag clutch, is that once engaged (through centrifugal forces) to crank the engine, I would noticed if the sprag slipped out and just the starter motor was rotating by the change is sound and lack of load on the battery? Or have I got a completely wrong visualisation of what happens?
 

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...
Any suggestions of a remedy would be gratefully received.
Hi and welcome here. It's your first post here, so I would first suggest you give a little bit more information on your bike. 2015 seems to be part of the first batches delivered for the TV. What is the mileage? What is your use of the bike...

That would be of help so any of us can be helpful...

Now that being said, beside the clutch, it could be ignition linked. Check all fuses first...
 

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Discussion Starter #5
Thanks for your message. The bike done 22,000 miles, with the majority (whilst I've had it since 2018) has been on long trips (3k to 5k miles at a time). Not used daily or for commuting.

The fuse link sounds interesting, please explain, as I though that once a fuse goes, its gone? Or are you suggesting it the cable that might be faulty?
 

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Thanks for your message. The bike done 22,000 miles, with the majority (whilst I've had it since 2018) has been on long trips (3k to 5k miles at a time). Not used daily or for commuting.

The fuse link sounds interesting, please explain, as I though that once a fuse goes, its gone? Or are you suggesting it the cable that might be faulty?
When a bike doesn't start, it may have multiple reasons. And for debugging reasons as well as power limitations, multiple fuses are installed. Main fuse is clearly ok, as well as the one leading power to the starter. It may not be the case of all of others...

Now, that being said, if it starts anyway after multiple tries, forget the fuse, and get your sprag clutch checked...
 

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Personally, I think your answer lies in the first lines of the problem description.

The start sequence for your bike includes sensors to tell the engine rpm and also voltage to the ECU and other circuits of the bike. If certain parameters are not met, the bike will not start. Not hearing the fuel pump prime on occasion is interesting because I thought a three second prime was always included when the key was first turned on. I will look into the manual for that.

It is unlikely that it is a fuse issue as fuses are on or off.

Now, what I believe is that your battery needs to be replaced. The 2015 bikes came with a notoriously weak battery and thea will affect the start sequence as the battery is depleted while cranking.

When did you last replace your battery and with what?
 

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Here are a couple of things that might help:

477607


This diagram walks you through what you need to have a successful engine start:

477608
 

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Discussion Starter #9
Thanks for the recent responses. The fuse explanation does not seem to me as a possibility, as was mentioned (either off or on), so the battery could be more plausible. I haven't replaced the battery whilst I have owned the bike (2 years), and do not know the history if it has been replaced beforehand. That said, the battery does seem to be pretty good, as I have attached a volt meter before and whilst cranking. Before it reads 13.7v, and during cranking 10.5v. Is that not sufficient for all the systems to function? And the battery does last quite a while during cranking before waning, and then recharges quickly once started. I also leave it on a battery minder when not being ridden.
 

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Right about the fuse being on or off permanentl (Did some diagonal reading while doing something else;)). Battery could be also. I remember mine dying in 2018 on 2015 TV. While the readings on the voltmeter seemed good, it did not allow more than one start at the end, and struggled to charge while riding ( long running time was needed to recharge it), and sometimes it did not start at first attempt. Replaced it the next day with a lithium battery and never experienced the issue again...
 

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The 10.5 volts indicates that your battery is toast.

The indicated voltage will not support ECU operation and is the most likely cause of your failure to start scenario.
 

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Discussion Starter #12
Many thanks for the contributions from you all. I think thank I will invest in a new battery and report back with the results when done. TTFN
 

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The 10.5 volts indicates that your battery is toast.

The indicated voltage will not support ECU operation and is the most likely cause of your failure to start scenario.
Hi! Agreed...You need a new battery...!!!
I had the sprag clutch replaced 3 times and I feel I became an expert. Every time it failed on me makes horrible grinding sounds. That being said, first of all you need a new battery and second you need to RUN to a Mv service center to have the latest map installed!! it is vital to the sprag clutch!!! if the problem persist, you need a new sprag clutch.
 

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+1 on battery. Eliminate the simple first. I replaced the OEM battery with an Earth-X LiPo with BMS. The difference in cranking authority was immediate. My suggestion would be to beg or borrow a known to be good LiPo battery that has the most capacity that will fit in the battery box and see if it makes a difference.
 

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Welcome to the family @MBD !! Where are you in the UK? Please introduce yourself in the "New Member"section and add you locale to your profile.
I'll second the battery...but unless you are into weight savings and prepared to buy an appropriate Li battery tender, I would suggest just getting a fresh Yuasa battery. Mine typically last 8+ years living on a good maintainer when not being ridden.
 

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Discussion Starter #16
Ok everyone, I've replaced the battery with a brand new fully charged BS Batteries Motorcycle Battery - SLA Sealed Lead Acid BTZ12S (I'm not fussed about a few kgs of weight savings), and now she won't start at all. She cranks over very much like before the battery replacement. However, interestingly, after the first attempt of turning over, when the bike went through the normal set up sequence of 3 second fuel pump etc. before the All OK, attempts to start her after the first failure of lots of cranking, the start up sequence gets to the 'all OK', but I cannot hear the fuel pump prime anymore! Any ideas?

I am guessing that some of you may come back and say still 'Sprag clutch', however, if you do, please explain (if you can) the rationale, because if when the starter motor engages the sprag clutch (through centrifugal forces) and cranks over the engine, surely the sprag is functioning? If the Spag were not engaging, I am assuming that I would only hear the starter motor spinning, and no engine cranking?
 

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I would first do a continuity check on FUSE 1.

Then check the Fuel Pump Relay.

477680


477681
 

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Also....look carefully at the wires going into your starer relay/main fuse. This 4 wire connector is known for developing poor contacts, excessive resistance, and resulting melted wires/connector.
Another consideration is your battery cables themselves, especially the ground cable ans its connection to the chassis/engine.
 

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Discussion Starter #19
Ok, so I've replaced the battery, I've checked the fuses, I've inspected (not corroded) and cleaned the 4 wire connector plug contacts. I've established that the sprag clutch must be working as engine is cranking and can feel & smell (hand over exhaust pipes) fuel/air mixture coming out when cranking under the starter.

It appears that the length of time before the engine starts after many attempts to start her, is taking longer and longer, and now the new battery is running flat.

I am running out of options for a logical explanation, and remedy?
 

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I do not have a TV;but, there have been many instances of folks not getting all the wires back in the correct terminals. I would charge the battery and recheck my work.
 
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