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6th Gen running/rideability issues??


MJH

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So, some quick background ... most likely related, but not entirely sure? Put between 1-2 gallons of gas in the tank that I did not realize had some 50:1 premix in it, but was with another 3-5 gallons of good gas, basically filling the tank at "home", prepping for a future ride. One issue could be, that I then didn't ride it for a week or so, so the "premix" prob settled into the bottom of the tank? When I did get around to going for a ride, everything was just fine ... ran great all day, a nonstop 3-4 hour ride, never stopped or dismounted, besides at lights/ stop signs, totally about 170ish miles, then it went to crap! Started acting like it was running out of gas, losing power, and would not accelerate from anything under like 7-8K? Above that, it definitely seemed to be running on all 4, but below that felt more like it was dropping at least 1 it not 2 cylinders?? 

 

Was getting to the bottom of the tank, so I figured what the obvious "culprit" was ... and was already set for my gas stop in the next 15-20 miles, but was only at the last bar on the fuel gauge, and not even blinking at me yet. As soon as I would close the throttle it would want to die, and I could keep it running with more throttle, but it was fighting BAD!! It died on me several times, trying to limp it uphill into the gas station I happened to come along, and I got it there. Hoping filling it up would "dilute" the "bad gas", and would be able to clear it out once full. No such luck ... it continued to get worse and worse, biggest problem was it would not pull under any sort of load ... i.e. HILLS!! Good luck not encountering hills in the Sierra foothills!! I tried to make over one section to where it would basically be near all downhill to get it back to the house ... no dice!! Racked up a total of 9 miles from the fill up, to where I gave up, and didn't want to risk making things worse!

 

Conclusion ... the last leg of my trip, which should had been under an hour, took me almost 6 hours, and a chaotic loading of the bike into the back of a borrowed truck, with less than idea tie downs/ramp etc. Reagardless ... was still a GREAT day on 2 wheels ... just a not so great conclusion. 

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So, it still would start and run, but as it got worse, the RPM needed to keep it running kept getting higher and higher ... so it was now more like hitting 8-9k to get it running on all 4, and it would die on it's own unless you kept giving more throttle, and even then, sometimes keeping it running was next to impossible.

 

So I start pulling it apart, drain the tank, pull the airbox, and look down the intakes with the throttles open ... and what do I see? Front 2 cylinders, #2 looked a bit "wet", and #4 is full of fuel! One of my biggest concerns/issues ... cannot figure out why the fuel would not run down past the valves into the crankcase? I already dumped the oil, because the crankcase was definitely diluted with fuel ... but am I missing a reason why the rest would not get through that cylinder, past the valves, rings etc.?? Something to do with the "VTEC" maybe?? 

 

I help the throttle open, before draining the oil out, and tried to crank the fuel out of the cylinder, but nothing seemed to change??

 

So, I'll leave it at that for now, and hope I get some tips/pointers on which direction to go? Planned on either pulling the injectors and manually cleaning them, as well as likely getting some new plugs into the bike ... I don't have a lot of background on the bike, and only had it a couple months. I kinda went through a lot of it, cleaning and checking over a bunch of little issues from the previous owners, but had no running/driveabilty issues ... 'til now!

 

So, with that, I'll see what comes back from the great knowlegable people on here ... Thanks in advance!!!

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MJH

 

sorry for your woes.

I don’t think a 50:1 fuel oil mix would cause any of this. Maybe a slightly oily exhaust and maybe fouled plugs.

 

When you say No #04 cylinder intake chamber was full of fuel was it both ports or just one? If both then either both valves were closed when you looked or you have something wrong with your cam shaft assembly. Remove the plugs and turn the engine over to cycle the intake non Vtec valve. If it is just one then the one that’s full of fuel would be the Vtec valve which keeps closed until 6800 rpm.

 

Now there shouldn’t be any fuel in large liquid form in any of the chambers because once you switch off the engine from running it would be warm and any wetness of fuel from the injectors/intake manifold would evaporate. To have large amounts of fuel in there it points at a fuel problem. With the air box still removed switch on the ignition to let the fuel pump prime. Is there any fuel coming from any of the injectors, especially No 4. If it is then the injector is leaking past hence the flooding. if leaking send for ultra sonic cleaning or replace with new ones if you can afford the cost. 
 

Is the FPR working that is screwed onto the end of the fuel rail. Disconnect the vacuum hose, does it leak fuel. If so the diaphragm has ruptured and will allow high pressure fuel back into the intake stacks through the vacuum hoses.

 

let us know how you get on.

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Sounds a bit like a ruptured Fuel Pressure Regulator diaphragm. This dumps excess fuel into cylinders 3 and 4 via the vacuum hose. Remove the vac hose from the FPR, is it dripping with fuel?

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I agree - the 50:1 gas is not the problem.  I keep a can of it around for power equipment and on a couple of occasions others inadvertently used it in non 2 stroke engines with no issues. If it's old and deteriorated that's a separate issue from the 50:1 mix.

 

If you doubt the valves are opening, with the engine off and air filter out you can roll the throttle wide open and look down the throttle body at the intake valves to see what's happening.  

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On 9/26/2020 at 2:42 PM, Marooncobra said:

MJH

 

sorry for your woes.

I don’t think a 50:1 fuel oil mix would cause any of this. Maybe a slightly oily exhaust and maybe fouled plugs.

 

When you say No #04 cylinder intake chamber was full of fuel was it both ports or just one? If both then either both valves were closed when you looked or you have something wrong with your cam shaft assembly. Remove the plugs and turn the engine over to cycle the intake non Vtec valve. If it is just one then the one that’s full of fuel would be the Vtec valve which keeps closed until 6800 rpm.

 

Now there shouldn’t be any fuel in large liquid form in any of the chambers because once you switch off the engine from running it would be warm and any wetness of fuel from the injectors/intake manifold would evaporate. To have large amounts of fuel in there it points at a fuel problem. With the air box still removed switch on the ignition to let the fuel pump prime. Is there any fuel coming from any of the injectors, especially No 4. If it is then the injector is leaking past hence the flooding. if leaking send for ultra sonic cleaning or replace with new ones if you can afford the cost. 
 

Is the FPR working that is screwed onto the end of the fuel rail. Disconnect the vacuum hose, does it leak fuel. If so the diaphragm has ruptured and will allow high pressure fuel back into the intake stacks through the vacuum hoses.

 

let us know how you get on.

Yeah, the fuel was sitting both ports. I had held throttle open, when the tank was still on, and it never seemed to clear the fuel out, so I was thinking it was either a VTEC/cam problem, but my familiarity with how the whole system is limited.

 

I didn't really think the "pre-mix" would be the entire culprit, but might had been related. I hadn't gotten around to pulling the plugs yet, but I will, as well as put the tank back on so I can "troubleshoot" some more? Got some more starting points, and sounds a bit like the FPR might be the issue? Hoping so, cause otherwise, I'm thinking might be some sort of cam/VTEC issue.

 

I'll probably dive back in tomorrow morning, and see what I find ... will keep updating.

 

Thanks for the help ... one and all!!

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On 9/26/2020 at 3:46 PM, Grum said:

Sounds a bit like a ruptured Fuel Pressure Regulator diaphragm. This dumps excess fuel into cylinders 3 and 4 via the vacuum hose. Remove the vac hose from the FPR, is it dripping with fuel?

 Yeah, from the previous reply, that is what I am "hoping" for?? Otherwise, I think the years/mileage, and questionable maintenance may lead to a valve train issue. Not the greatest of news, if so, ohhhhh well ... got it for a bargain price, so rebuilding it, or getting a lower mileage motor to swap in??

 

Thanks for helping ... I'll update as I get more info.

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On 9/26/2020 at 8:34 PM, BlackheathMatt said:

So poor running deteriorating to the point the bike would only make power at revs when the vtec valves operating - and then a cylinder full of fuel 

 

Sounds like the non vtec exhaust valve on the affected cylinder not opening fully or at all for some reason.

 

If the previously mentioned FPR is not the issue, the I was already thinking that I got some issues with a valve or multiple valves just not "functioning" ... meaning a worn out/flat cam or lobes. Hoping not, but sure seems to keep pointing in that direction??

 

Thanks for the feedback!

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Sorry not to be more helpful. Not VFR specific but have seen broken springs cause dropped valves in car engines before.

 

Goes without saying be aware of the risk of further damage to rings/con rod by running an engine that's trying to compress an incompressible liquid in one cylinder.

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