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Discussion Starter #1 (Edited)
Hi All again,

Sadly, due to an unknown bug (identified now as Forum-COVID-20) in the StromTrooper system, my original post (and login details) were deleted. I had written war and peace regarding the issue, but I will give the five minute version.

Problem:
Once warmed up, the bike would bog down/misfire with large throttle applications. The more the bike was ridden, the worse it got. It was most noticeable above 5000rpm. The wider you open the throttle, the worse it got - if you backed the throttle off to a 'slightly accelerating' position, the bike would tend to accelerate up to about 5500-6000rpm before starting to misfire again.

Initial thoughts and problem solving:
It felt like fuel starvation of some sort - whether this was due not enough fuel being physically available for injection, or whether the dreaded TPS issue wasn't allowing enough fuel to be injected. Either way, it felt like with more air there wasn't enough fuel to be a stoichiometric mixture. In order to look into it, I did the following checks:
  • Put the bike into dealer mode, "_C00"shown at tick over with the motor running, so no obvious sensor issue. Bike ridden in dealer mode and the TPS mark would move at reasonable times.
  • Pulled the rear spark plug to have a look. All looked well, though they were original from 2013. After no significant results from the below investigations, I put a new set of plugs in to rule them out. No change.
  • Checked for blocked tank vent. Tried a short burt of acceleration with the fuel cap popped (and not too much fuel in the tank!) as well as checking that the vent hose was letting vapour out. All seemed to be as normal and there was no difference to performance.
  • Pulled off the fuel tank and pulled the fuel pump out - the strainer was full of horrid gunk which I cleaned off it by bathing it in methylated spirits multiple times. I cleaned the remainder of the fuel pump assembly and the bottom of the fuel tank. I also inspected the inside of the fuel tank, but there were no signs of rust etc. After re-assembling the tank, the bike seemed to go okay for a little while, however once it warmed up, the problem came straight back.
  • Pulled off the O2 sensor and tested it to ensure it was generating voltage - test came out okay.
  • Checked the connection, condition and seating of the TPS - no obvious issues (though I realise this doesn't preclude there being a problem with it).
  • Checked the freedom of movement of the upper butterflies and lubricated their pivot points - some slight resistance but nothing serious. Now very free-moving but no impact.
  • As there was no further fuel filter in the 2012-2016 DL650, I thought that I had gone as far as possible with the fuel system, short of the pump being on the way out.
  • Importantly, I had noticed that when I first started the bike, even when it was hot, it seemed to pull through to high RPM once, but not again after that.
  • Put in some injector cleaner and rode the bike a reasonable distance in order to see if it was gunk from the strainer that had made its way into the injectors and was stopping high volumes of flow. No difference.
Input from other StromTroopers:
Unfortunately, their posts also got deleted in the Forum-COVID-20. They gave some excellent advice which resulted in the fixing of the bike. Apologies to this guys for the delayed response, but I was hoping that our thread would somehow miraculously appear like Trump's plan to have everything rolling in time for Easter... bizarrely, it didn't work out like that.

Cryoman:
3 thoughts:
Unlikely but check: side stand switch is being activated because of a loose spring.
Unlikely but check: high pressure fuel filter is clogged, perform fuel flow test
Most likely:TPS Issue: When the throttle is opened fully, the motor bogs down and loses power. Back the throttle...

Blaustrom:
I would say your syptoms are classic fuel starvation because of a partly plugged up high pressure filter. First do the fuel flow test and report back.

1 other...?

Solution!
Thanks for all your respective help with thinking about the problems with the bike - looks like I have fixed it!

Did a fuel flow test, only just got the minimum numbers stated in the maintenance manual of 167ml in 10 seconds. The forums had indicated that it should be a figure closer to 300ml from most people's experiences.

Decided to pull apart the fuel pump again and try cleaning the pressure regulator as that seemed to be the only element of the pump assembly that I hadn't cleaned thoroughly and could be stopping the pump working effectively (unless the pump was damaged by the crap it had to pump previously).

Unlike the original DL650/1000, the 2012 onwards model doesn't have a second filter, only the initial strainer, so any blockage beyond the pump would have to be a result of the pressure regulator.

I soaked the pressure regulator in methylated spirits for about 15 minutes with the odd shake, as well as rinsing the strainer and pump again. Put it all back together and did another fuel flow test - this time I easily got ~300ml in three cycles of the key (approx 10 seconds running time for the pump).

I also removed the TPS and ensured that it was clean and checked the connection, but nothing untoward externally. Reinstalled in the same position as marked by a paint pen across the top prior to removal.

On the test run, I allowed it get up to temperature before giving it a wrist-full, as it was when it was hot that it seemed to be struggling. After getting it up to 3 bars on the temperature gauge, gave it full throttle and it pulled cleanly through the rev range. Rode along for another 5 minutes and then proceeded to repeatedly accelerate to the red line throughout the gears - not a cough!

Looks like a partially blocked pressure regulator was the issue. My explanation as to why it would work whilst cold/after first start is that when it's cold, the engine management system is trying to give it more fuel and less air anyway in order to make the mixture rich enough. If it was turned off and back on again, it would prime the system as the key went on and provide a small additional overpressure of fuel prior to starting. This would leave sufficient pressure in the system to do one pull to high revs, but not enough for a further high throttle application.

Not conclusive by any means, as I have no fuel flow data from the ECU, but I think it fairly well explains the symptoms.

I have now ridden the bike about 300km since the fix, including plenty of 'spirited' riding. Not a cough and performing very well indeed!

On the upside, now it has new spark plugs, a clean fuel system/tank and an owner that knows a bit more about how it works.

Thanks for your help!
 

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This is the first time I read that the newer 650 models have no high pressure fuel filter. I wonder if there is anybody else that has investigated the design of these pumps?

Dirtstrom: Very well summarized. The other "1 other...?" was blocked tank vent. This is very rarely reported here, so quite unlikely.
 

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Discussion Starter #4
Thanks Blaustrom.

There is no distinct high pressure filter. The description in the manual doesn't talk about a high pressure filter either, though it is marked on one diagram (but never referred to in text or included on the subsequent tear-down diagram). I have included both images from the manual as attachments.

I did check the blocked vent - I will edit my post. Tried a short burst of acceleration with the fuel cap popped (and not too much fuel in the tank!) as well as checking that the vent hose was letting vapour out. All seemed to be as normal and there was no difference to performance.
270806
270807
 

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Discussion Starter #6
Yes, that's what I was referring to in my description above - it is only marked on that one diagram as #7, but there is no mention of it in the description or in any other part of the fuel system section. It is also not shown in the tear down of the fuel pump in the second diagram.

Unless #7 is integrated into the plastic housing that the pressure regulator sits in above the pump and is not visible when looking into any of the holes? I had a good look at it and could only see white plastic, the same as the outside body, through each hole.

I did soak/flush this assembly too in case there were bits of gunk stuck inside it, but nothing of any significance was flushed out.
 

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Discussion Starter #7
Have had another look at some other forum posts - what a silly piece of design! To have it completely invisible in that housing is very poor indeed.

I will implement the filter bypass when I next get some time to pull the bike apart.
 

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I was under the impression the regulator assembly includes the ceramic high pressure filter. kfh000
 

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Discussion Starter #9
It seems like it is located in the plastic housing which the regulator fits into, however there was no obvious sign of it when I disassembled the fuel pump. I had interpreted it as a legacy drawing which had not been updated when the new manual was produced, as they did not mention it in any other section, however it must just be considered a non-serviceable item and have not talked about it further, strange as that is.

Thanks again for all your help.
 

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Yes, the filter is integrated into what is refered to as the fuel pressure regulator assembly. The upper section of #2 in the 2nd drawing. The sctual regulator is a metal assemble that looks a lot like a PCV valve. I did this mod and replaced the pump too a few years ago. You'll be amazed at the crude that washes out of the filter, though you may have already gotten most of it out. VSRI has detailed instruction on the filter bypass. Sorry I don't have a direct link to the procedure.
 

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I had the same exact issue with my new 2014 leftover that I bought last summer, at 700 miles it was not rideable. The dealer finally test rode and and found that anything over 60mph was hard to achieve. The folks on this forum told me it was probably the fuel pump/fuel filter, and I would have cleaned it myself, but it was a new bike so they replaced the fuel pump under warranty and totally cured the issue. Must have had very old gas in it when I got it, though they denied that too.
9fingers
 
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