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Engine dying when coming to a stop


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OK I moved this to a new thread so I wouldn't hijack some else's.😐  To recap my VFR was dying most of the time whenever I came to a stop at red lights or stop signs and occasionally just decelerating into a tight turn.  It would always start right back up no prob but the same would repeat at the next stop.  Idle is where it's supposed to be, new fuel pump, cleaned and balanced injectors. plus I could find no loose vacuum lines or loose connectors.  To me the simplest and easiest troubleshooting was to unplug the Power Commander III and see what's up.  I did exactly that and took it for test ride #1 this afternoon and could not get the bike to repeat the problem. Hmmm.  I will repeat test ride tomorrow to be sure but so far it is looking like the PCIII may have been the culprit.  So my question is does that mean the PCIII was defective or could it have just been a bad map?  I have  zero experience with the PCIII's but have found an online manual @ DynoJet's website.  Also another question is does the bike even need this PC?  It is my understanding that the stock ECM is pretty capable of adjusting to changes such as my Two Brother's Pipes.  Does the PCIII actually improve HP, Torque, or MPG?  Or does it just give you controllability?  Thanks for any advice or sharing experiences with this.

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Know nothing about a PCIII but I have read where there have been running issues caused by bad Grounds for the PC. So have a good look at the wiring for it and make sure both power and ground wires have good solid connections. At least you've identified the culprit to your engine dying issues.

Cheers.:beer:

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Bike ran perfectly fine when it left showroom floor. There is no reason it shouldn't now if maintained in good condition.

 

It's air-flow mass that determines power and fuel & ignition needs to match for optimum output. With your mods, there is absolutely zero reason to have PCIII on your bike. Only needed if you've got extreme mods that factory ECU cannot adjust for. Such as big-bore high-comp pistons on stroker crank, larger valves with fully-radiused seats, D-ported intake-tracts, turbo or supercharger.

 

If you've got driveability problem, it's most likely maintenance issue. Worn plugs, cracked plug wires, dirty injectors, clogged fuel-filter or sock screen. This causes issue with spark and fuel. Using PC to try and compensate is not solution. Proper troubleshooting with testing and measurements to find faulty or misadjusted components is correct procedure. Followed by replacing worn-out faulty part and re-adjustments. Mis-adjusted TPS sensor and idle-switch is very common culprit.

 

In this case, very common for PC to cause more problems than it helps. Restore bike back to factory-fresh clean condition and it'll run perfect like when it left showroom floor. You're halfway there with disconnecting PCIII, now remove it completely and you've solved problem for good.

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OK after second test ride the issue has completely disappeared so obviously it WAS the PCIII. So since I am removing the PCIII I'm guessing I need to remove the O2 eliminators as well?

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no. you can leave those alone for now. Make only one change at a time.

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Had a similar problem with my 06 and a PC3. Turned out it was that where I had the PC3 located, which was in the space just behind the rear brake fluid reservoir shown in red. My sergeant seat had a tab on the underside that pressed on the PC3 when I sat squarely on it, like when stopped at a light, and it would start to misfire from then on. Went through all types of troubleshooting until I noticed the indentation on the PC3. I shifted the position of the PC3 to avoid the tab and has been working perfectly ever since.

 

 

PC3 space.JPG

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I had a similar problem with my VFR.  But I have a Bazzaz Zfi installed.

 

Whilst the Bazzaz was installed properly, according to the instructions, I really hate the use of scotchlocks.  They might work for a while, but in the end - in my experience, they just result in bad connections.  I traced it to the fact that the scotchlock that was connected to the switched power lead was dodgy.  I removed it and soldered the wire instead.  Then went around and removed the other scotchlocks that were used with the Bazzaz Zfi and haven't had any problems since then.

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  • 2 months later...

Update:  After removing the Power Commander 3 and the problem disappearing, it began to resurface 3 or 4 days later.  I started keeping track of when this problem would occur and under what conditions.  It took quite a while but suddenly one day I had an AHA moment. I knew the culprit.  But to be sure I started predicting when it would occur and when it wouldn't.  And I was right every time.  It is a fuel pickup problem happening inside the gas tank.  Only when I have 1/3 of a tank or less and as I come to a stop the remaining fuel is thrown forward to the front of the tank -- away from the fuel pump and its pickup --  and the injectors are starved of fuel and the engines dies.  After coming to a complete stop the remaining fuel in the tank sloshes back and levels out and the pickup can get fuel again.  The bike restarts easily, idles fine, and accelerates like a demon.  Until I come to a stop again and the problem reoccurs.  Fill the tank up and the problem completely disappears until it gets back to the 1/3 full level and it all starts over.  Removing the PC3 fooled me because I filled the tank up at the same time making the problem disappear.  I broke the cardinal rule of troubleshooting and made 2 changes at once.🙁.  So then after taking it to the dealership to let them confirm and possibly fix the problem they discovered that the tank etching and lining process to remedy 5 years of storage with bad fuel left in the tank did not take and is already beginning to bubble and separate  from the inside of the tank.  The rust damage was just too great.   Sooooo I've got to replace the tank.  ☹️.  I have located an '04 tank in pretty good shape for an excellent price (😉🙏 thanx Curt) and posted the question of fitment to my '05 and (🙏 thanx to Cogswell) he has assured me that the fitment will be the same. 

As a side question,  is there anyone here who has seen the inside of these tanks and can tell me whether or not there are baffles welded into the bottom and/or sides?  That seems to me would prevent my problem from happening but maybe mine got rusted out during the 5 years of storage?  As far as I can tell there is no way to change the height or level of the fuel pickup to fix the problem so I am hoping that just replacing the tank will solve my problem.  If anyone knows different please inform me and have my gratitude for the education of a VFR dummy. 🤪

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4li3nvfr

 

No baffles in the tank. It’s an unusual fault as the last time I replaced my pump the pick up is right at the bottom of the pump near the tank bottom and located inside, what I would call an aluminium scrubbing pad. There is also a very fine screen filter fitted on the inlet as well. There is a rubber hose that connects the main filter and this could have a hole in it. Apart from that the pump is securely fitted to the assembly so movement of the pickup would be strange.
 

Does your fuel gauge indicate correctly as it could be that the float has been bent and although it says you are at 1/3 full it could be you are almost empty, hence fuel starvation?

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That is a possibility but I doubt it because I can continue riding for another 40 or 50 miles or so without running out.  The problem may be the fact that this is a replacement non-OEM fuel pump.  Maybe the fuel pickup mounts differently to it and is raised up a little too  high?  I have not personally laid eyes on this because my local Honda shop has done the work.  I will ask them about it.  Thanks for the info.

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12 hours ago, 4li3nVFR said:

That is a possibility but I doubt it because I can continue riding for another 40 or 50 miles or so without running out.  The problem may be the fact that this is a replacement non-OEM fuel pump.  Maybe the fuel pickup mounts differently to it and is raised up a little too  high?  I have not personally laid eyes on this because my local Honda shop has done the work.  I will ask them about it.  Thanks for the info.

Think you are onto it, especially as you have a non oem pump. I wonder if the whole assembly has been replaced or only the pump? 

Attached is the fuel pump description taken from the 5gen Service Manual, I'm sure the 6gen won't be too different. It specifically states the pickup is within its own tank to prevent the issues you've had. Perhaps this tank is missing around your mesh filter.

 

IMG_1127.PNG

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Awesome!  Thank you Grum for the pic and text.  That definitely helps me see what is going on in there. I'm gonna show it to the Honda guys in case they don't have it.

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12 hours ago, 4li3nVFR said:

Awesome!  Thank you Grum for the pic and text.  That definitely helps me see what is going on in there. I'm gonna show it to the Honda guys in case they don't have it.

Here's a view from the 2005 6gen parts list, item 6 shows the rubber tank arrangement for the fuel pickup.

 

20210729_225510.jpg

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7 hours ago, Grum said:

Here's a view from the 2005 6gen parts list, item 6 shows the rubber tank arrangement for the fuel pickup.

 

20210729_225510.jpg

Grum, sir, you ARE the GOAT!👑🙏

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  • 3 weeks later...

My ‘04 does this too. At about 1/3 of a tank it will start to do exactly as you have described. I’ve owned mine since new so I know my parts are all OEM.  I usually just try to keep the tank above 1/3 full.  If you figure it out please post the fix, I’m very interested.

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  • 3 weeks later...

UPDATE:  My local Honda shop installed the replacement tank and it now has all new innards according to the diagram that Grum so nicely provided.  Unfortunately when taken for a test ride the dying issue remained with <1/3 tank of fuel. And to make matters worse (by throwing gasoline onto the fire)😆 heh, sorry.....the non-OEM fuel pump that was recommended here in the forum has shorted out and melted its wires.  Rather than replace it under warranty and risk having the same thing happen all over again I have decided to bite the bullet and purchase an OEM Honda pump at a slightly discounted price.  Hopefully this will abate all problems and I can be back on the road soon.  Wish me luck or offer alternative advice.  Either would be greatly appreciated.

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I certainly wish you luck. Having a fuel pump short like that is unusual, was there any chance the pump was running dry? Sorry, just realised that can't happen, as soon as the engine stops the ECM kills the Fuel Cut Relay stopping the pump.

Sounds like an expensive repair. I guess you have no other alternative than to get the tank back to OEM spec and take it from there.

The other thing that sticks in my mind when not doing the job yourself, is having the confidence whoever does the job does it properly!!

Keep us posted.

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This sure is an unusual and I'm sure frustrating problem.  The best I can do is like Grum and wish you the best with it.  And +1 on letting us know how it goes. 

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UPDATE #3:  Got the bike back today with OEM fuel pump plus all new innards of the tank installed.  The Honda shop took it for two separate test rides on different days with the tank near empty and had no probs, said it ran great.  I tested it personally with the tank near empty and NO dying when decelerating or coming to a stop.  Yay!😁  Tank is full of 93 octane now so we'll see if it continues to behave correctly when the tank gets near empty again.  Wish me luck. Will update again in a few days.

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Wow...this makes me want to get hot on my fuel tank/filter/injector replacement project! 🙃

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1 hour ago, 4li3nVFR said:

UPDATE #3:  Got the bike back today with OEM fuel pump plus all new innards of the tank installed.  The Honda shop took it for two separate test rides on different days with the tank near empty and had no probs, said it ran great.  I tested it personally with the tank near empty and NO dying when decelerating or coming to a stop.  Yay!😁  Tank is full of 93 octane now so we'll see if it continues to behave correctly when the tank gets near empty again.  Wish me luck. Will update again in a few days.

That's great news. Certainly sounds like the new oem pump has solved the problem, expensive as it is.

I'm still surprised that the non oem caused the problem, perhaps it was not the exact type for your bike or was poorly fitted, perhaps with some sort of damage to the fuel pickup area, who knows? The important thing is you have the matter solved and your bike is reliable once again. Enjoy the riding.

Thanks for keeping us updated.:fing02:

 

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  • 3 weeks later...

UPDATE #4:  Three tanks of 93 octane have come and gone through my VFR fuel system and the bike is performing flawlessly.  No more dying when tank is low.  YAY!👍

Added benefit:  recently we've had a couple of 51 degree mornings and the VFR is loving the extra power...seems like 30 more horsepower....🏍️!

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2 hours ago, 4li3nVFR said:

UPDATE #4:  Three tanks of 93 octane have come and gone through my VFR fuel system and the bike is performing flawlessly.  No more dying when tank is low.  YAY!👍

Added benefit:  recently we've had a couple of 51 degree mornings and the VFR is loving the extra power...seems like 30 more horsepower....🏍️!

Mate, this is great news and thanks for the good follow up, we can all learn from this.

So it proves that your non OEM pump must have had an issue with the fuel pickup area, or perhaps a faulty installation or damage caused with the installation, would love to have had a close look at the removed pump.

Glad your OEM pump has solved the issue. Enjoy the ride:fing02:

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