My Bike's Struggles with Acceleration and Higher Speeds

[Phil Tarman]

I've posted before about the bike feeling "choked" when I try to give it more than 3/4 throttle. It got so bad on the way back from Spearfish (after doing fine most of the way to WV, all the way up to Spearfish and from Spearfish to Torrington (a little over 200 miles from Spearfish) on the way home. Ken Malone (RedBird on the Forum) and I both gassed up there, but my bike started running badly before we'd gotten much south of Torrington. By the time we left Pine Bluffs, WY, I couldn't get up to 70, and as we left Cheyenne I was doing well to get t0 65 and I couldn't hold that speed uphill.

So, I finally got around to taking the bike to the shop, fully expecting to be buying a fuel pump. But so far, the mechanic working on the bike is mystified. He's in the process of putting it back together now after pulling the throttle bodies and doing whatever gets done to them. There were some old codes in memory, but none that related to the problems I've been having. So far, all I'm spending money on is labor. The mechanic says it's being a learning experience.

I'm hoping that it gets back together and running right so I can make the MSTA ride to the Boathouse Cantina in Salida, CO, next Friday.

 

[seagrass]

Phil this reminds me of a few years ago when I was travelling with a friend to the VJMC rally in South Austraila. It was about 1100 miles each way and along the way after both of us filled up at a Caltex service station my friends bike started running rough.

When we next filled up, at a BP service station, his bike ran OK. As I travel with a Caltex fuel card (pre-paid fuel card) I chose to next fill up at Caltex again and to our surprise my friends bike started running rough again.

For some unknown reason my friends bike would not run well on Caltex fuel but ran OK on the BP fuel.

I wonder whether you are having a similar problem. The big difference is that my friends bike was a Suzuki XS650 with carburettor and no ECU and the NT should compensate for minor fuel variations.

Seagrass

 

[Phil Tarman]

Seagrass, I don't think that's the problem. The first times I ran into this issue was back in October of '17. On that trip I fueled up at Conoco, Sinclair, Texaco, and Chevron stations and the brand of gas I bought didn't seem to make any difference. The issues I experienced coming back from Spearfish might be related to the brand of gas. I bought the last tank at a Cenex station. Cenex is a sort-0f off-brand so I guess it could be part of the issue if I hadn't had the same issue ten months ago while running several different brands of gas. I guess we'll see...or not.

 

[tawilke46]

Phil, also could you have purchased your fuel shortly after the storage tanks were filled? Water sits on the bottom of the storage tanks. When the tanker truck filled the underground tank, it could have stirred up the water up in to the fuel.
Had an experience with water in the fuel coming back from Florida many years ago. Filled up in St Petersburg, can’t remember what fuel as this was back in 1974. Car was running rough, could barely maintain 45 to 50 mph. Stopped in Tallahassee put some fuel conditioner in the tank with some fresh fuel. Still ran real rough and could not maintain the speed limit.
After getting back to Baton Rouge the dealer found water in the fuel filter. New fuel filter after cleaning water out of fuel system and my problem was solved. Ran perfectly......
If I see a fuel tanker at a gas station, I move on to another station.

 

[ARKNT]

Good luck with your issue Phil. As it seems intermittent it may be tough to find. It seems someone here mentioned the fuel pump and/or filter. Is your mech checking those?

Brad

 

[Phil Tarman]

I think he's checking the fuel pump and filter...I'll make sure that he has. I guess it's possible that water might have been in the fuel I bought and not in RedBird's. There were three pump islands and a lot of tank caps in the area. RedBird did use a different pump, but we both got the same grade of fuel.

 

[junglejim]

Maybe if you added some of your stove fuel to your gas it would cure the issue.

More seriously, Dudely's problem is more likely be a fuel delivery system problem than the fuel itself. The bike's response to the Seafoam you added indicates that. NTs are not very particular about fuel in general (water is a different issue). I use Cenex a lot because around here some stations sell non-ethanol regular and my bike loves it. Here is hoping your mechanic gets yours fixed.

Dudley is probably just waiting for a more inconvenient time to stall out completely - like when you're 100 miles from home and it is an hour before a big storm hits. At least it should be easier to diagnose then (after the rain stops).

 

[Macka]

Phil, I have mentioned previously that I had identical (intermittant) problems and found the filter blocked. A new tank unit solved it. You cannot buy just the filter but I now have a spare used pump.

Macka

 

[Phil Tarman]

BTW, I did offer to sell you a 2011 NT700V with 30,000 miles with all the farkles possible on it in pristine condition...

That might end up to have been a better deal.

 

[Macka]

If you have to take the fuel pump out to replace the filter, is this something that you could just clean the filter on, and then reinstall? Chris

The filter and pump can be separated but the filter is a High Pressure moulded plastic unit.
It may be possible to install some other (small) EFI filter in place but you would thereafter have no fuel gauge as the sender unit is mounted (screwed) to the top of the filter.
I guess that someone (engineer) could spend a few hundred hours redesigning it to make it work but my time is more valuable to me than that!

Macka

 

[ARKNT]

I remember a magazine (probably motorcycle consumer news) doing an article on a kit to replace just a filter but that was not on an NT with fuel sender mounted to it.

Brad

 

[Brillot2000]

The issue sounds to be in the fuel delivery system but can be misleading. When the bike is at speed, its demand is at its highest. If the fuel pump is not keeping up with the demand for the bike, it basically starving for fuel. If there's a fuel filter, it should be replaced. I do recall someone mentioning that the fuel filter is a part of the fuel pump assembly and cannot be purchased separately. This certainly puts things into a pickle.

Issues with the throttle body or fuel injectors will probably throw a code captured by the ECU. Fuel flow related issues would not throw a code. Decreased fuel flow can be caused by two basic issues, a restriction in the fuel filter or a failing fuel pump.

There is another possibility, the system voltage is dropping under a heavy load and causing the ECU to operate its threshold voltage and dipping below it from time to time. "Dips" in the operating voltage would also affect the performance. Just another possibility to look at. I suggest that you look into monitoring the battery voltage under operating conditions as well.

I am suggesting the above based on the that the ECU is an electronic device that requires a steady and stable voltage level to operate correctly. The entire bike relies on the ECU to operate and maintain its performance. Items such as these are overlooked by mechanics, however, this is something a system engineer would look at.

 

[Macka]

Initially I was very sceptical about the filter being the problem as it was intermittant and over a period of nearly 12 months.
99% of the time the bike would run normally.
Just very occassionally it would "hold back" and on one occassion it rolled to a stop but started again immediately.
With my experience I knew that it felt like low fuel pressure or a restriction but it happened so rarely that it seemed illogical.
During this period of intermittant trouble the bike would still pull 165kph multiple times.
Since replacing the tank unit I have done nearly 3000km and it has been perfect with even better power than before.
I have not hit 165kph since then but have done 140kph a couple of times.
On removal, the filter was extremely blocked.

Macka

 

[Phil Tarman]

Macka, I went by the shop today and talked to the mechanic. I told him about your experience and he said that he was going to be looking in that direction. He had planned to run a check on the fuel pressure, but their shop didn't have a connector that he needed (I think it was a connector to put on to the fuel line, but I'm not sure about that). If it turns out that I do need a fuel pump, I'm guessing that I'm looking at least another week before I can ride again. :-(

I told the service manager that at the rate this was going, I was going to end up paying them rent for the work table than for labor and parts. He assured me I wouldn't have to pay rent. He didn't assure me that I wasn't going to have to pay them a bunch of money.

Shoulda' bought that pristine, well-farkled 2011 NT.

 

[Macka]

Phil, I did not have a suitable connector for my Fuel Pressure Gauge either.
Rather than stuff around trying to find one I trusted my experience and just replaced the assembly as I was 95% sure that I was right.
Sometimes you have to trust your judgement in your trade without being able to prove it!
It was the same when I had the failing MAP Sensor.
That one took me ages to pin down as well and it was more or less confirmed almost by accident.
Replacing that Sensor solved that problem.
Obviously, from this distance, I cannot positively diagnose your problem but I believe that your symptoms "fit the bill".
If your engine loses power under load but recovers when you back off the throttle I would be confident that the filter is the cause.

Macka

 

[DirtFlier]

I believe the filter is integral with the pump and cannot be replaced separately. Now, whether or not it can be cleaned once removed from the tank is unknown.

 

[Macka]

Further to my post below, even if the mechanic can get a suitable connector for his gauge, it will only show low pressure/flow if that is so.
Access is also a major problem.
As you can only test the pressure/flow outside the tank it still will not tell you whether it is a weak pump or a blocked filter.
It is not possible to test the pump itself without removal, dismantling and testing in a substitute immersion tank.
I have never heard of any workshop (including mine) with such a facility.
EFI specialist workshops MAY have such equipment but I don't know of any near me.
It is far cheaper, quicker and easier to just replace the pump and hope for the best, having eliminated as many other possibilities as you can.
Sometimes you just cannot get a 100% answer.

Macka

 

[Macka]

I believe the filter is integral with the pump and cannot be replaced separately. Now, whether or not it can be cleaned once removed from the tank is unknown.

No, it cannot be successfully cleaned. Mother Honda has made sure of that!
You could cut it open, remove the paper filter and fit some other substitute paper filter if you could find one the right shape to seal internally.
Then you would have to rejoin the plastic body and seal it against 3 BAR pressure successfully or you are going to have your fuel pressure being dumped back into the tank and have the same loss of power as now.
As I said before, if you have unlimited time and the will to try, it MAY be possible.
Life is too short for that as I have recently found out.
If I can be bothered, I will take a picture of my old filter and post it here but there are many pictures of used tank units on Ebay.
Have a look there.

Macka

 

[Brillot2000]

No, it cannot be successfully cleaned. Mother Honda has made sure of that!
You could cut it open, remove the paper filter and fit some other substitute paper filter if you could find one the right shape to seal internally.
Then you would have to rejoin the plastic body and seal it against 3 BAR pressure successfully or you are going to have your fuel pressure being dumped back into the tank and have the same loss of power as now.
As I said before, if you have unlimited time and the will to try, it MAY be possible.
Life is too short for that as I have recently found out.
If I can be bothered, I will take a picture of my old filter and post it here but there are many pictures of used tank units on eBay.
Have a look there.

Macka

For those willing to rebuild their fuel pump assembly themselves. I found this rebuild kit on eBay, KENRO New Carbon Fuel Pump Honda NT700V 2010-2011, Replaces Honda 16700-MEW-D41

 

[mikesim]

For those willing to rebuild their fuel pump assembly themselves. I found this rebuild kit on eBay, KENRO New Carbon Fuel Pump Honda NT700V 2010-2011, Replaces Honda 16700-MEW-D41

Curiously, the Ebay listing references the NT700V part designation (MEW) however when you enter the NT's info into their compatibility checker it says that the Kenro pump is NOT compatible with the NT700V. Methinks I would stay with a genuine Honda pump..... The strainer sure does look an awful lot like some of the strainers we have for electric fuel pumps.

Mike