Engine Fluttering Sound

[thanosgp]

I do not have the ability to test fuel pressure myself but I spoke with a friend who is more mechanically smart that myself with motorcycles and he mentioned he might have some sort of inline tester that goes between the fuel line and fuel rail. Trying to coordinate that with him. At one point my attention was focused on a potential fuel pressure problem and I even did some research to determine if the bike had a fuel pressure regulator but most of my searches only returned the fuel pump sending unit. Replacing the fuel pump has always been in the back of my mind just trying not to go there quite yet.

Sorry to hear about your problems. I had similar gremlins with random stallings and heavy vibrations at 3-4000 rpm, or above 120-130km/h.
Like you, nothing cured my worries until i changed the fuel pump.
Upon turning over the engine the pump would hum and sound healthy ,but the unit wasnt. Please do not use the Honda part cause its very expensive.In fact ,it had the Mitsubishi logo on it,indicating a quality item.My mechanic found a similar automotive pump for 60 euro and since then it works like a charm. The access to the pump thou is a p.i.t.a. Hadnt heard another pump fail except of a guy in germany with an integra 700 (same bike but selling with different bodyworks as a scooter)who paid aprx 500 euro parts and labor .
I had reached the point of wanting to sell the bike. Glad i didn't. Wont part with ,it unless it lets me down multiple times.
Greetings from Greece,hope the sution is near.


Στάλθηκε από το MI MAX μου χρησιμοποιώντας Tapatalk

 

[rippin209]

I know the fuel pump in newer vehicles is lubricated by the fuel, I'd imagine the fuel pump in the NC is similar, have you run out of fuel at all?
Then again it could have simply failed without a reason.

 

[Jt105]

You can buy just the pump motor for $70. You will need to pull the pump assembly and replace the motor...
Quantum T35 Intank Fuel Pump With Strainers For Honda NC700X 2012-2018, Replaces Honda 16700-MGS-D33
Quantum T35 Intank Fuel Pump With Strainers For Honda NC700X / NC700XD 2012 2013 2014 2015 2016 2017 2018, Replaces Honda 16700-MGS-D33

I was curious and did a quick search and found this part. It looks to me like it would work.

 

[thanosgp]

I know the fuel pump in newer vehicles is lubricated by the fuel, I'd imagine the fuel pump in the NC is similar, have you run out of fuel at all?
Then again it could have simply failed without a reason.

Right!Big mistake to ride any bike on fumes ,thus stressing the gas pump with less lubrication.I never rode my bike till the canister was empty and put only premium gasoline in my nc.However it gave up on me.When my mechanic and me took out and cleaned the filter attached to the pump, the gunk inside the tank and the filter after 36.000km was horrible.Maybe the additives inside newer gasoline attacks o-rings and builds up gunk.I am 47 yrs old and ride bikes with clutch sfor 35 yrs.Changed many bikes all ,2nd or 3rd hand ,but never had any major problem.My nc is my first new purchased bike ,given me lots of grief till i sorted things out.However, it is the ABS-CBS model and i will never give it away if it continues to be reliable!

 

[thanosgp]

You can buy just the pump motor for $70. You will need to pull the pump assembly and replace the motor...
Quantum T35 Intank Fuel Pump With Strainers For Honda NC700X 2012-2018, Replaces Honda 16700-MGS-D33
Quantum T35 Intank Fuel Pump With Strainers For Honda NC700X / NC700XD 2012 2013 2014 2015 2016 2017 2018, Replaces Honda 16700-MGS-D33

I was curious and did a quick search and found this part. It looks to me like it would work.

Thats exactly what i did. You replace only the motor ,that you purchase with new o-rings and new filter.Then youre good to go!

 

[showkey]

Getting the bike ready for the first spring ride.........so..........was able to provide another data point.
Repeated the compression test on the NC without opening the throttle. ( all other variables were the same)
Reading was close to 130 psi

Repeated compression test with open throttle and it was again 250 psi.

At always very risky to jump to conclusions and skipping important tests.........but........125 psi “looks” to a good value given the test protocol used in prior tests.

 

[SergeantChuck]

Getting the bike ready for the first spring ride.........so..........was able to provide another data point.
Repeated the compression test on the NC without opening the throttle. ( all other variables were the same)
Reading was close to 130 psi

Repeated compression test with open throttle and it was again 250 psi.

At always very risky to jump to conclusions and skipping important tests.........but........125 psi “looks” to a good value given the test protocol used in prior tests.

I appreciate your taking the time to do this again. I did not have an opportunity to retest the compression this weekend but hopefully will have time this weekend. Having a hard time finding free time. It makes me feel better that you came up with the same psi without the throttle wide open.

I probably shouldn't but I'm still riding the bike even though she is not in tip top condition. Probably why I'm not in such a huge hurry.

 

[SergeantChuck]

The access to the pump thou is a p.i.t.a.

I assume it will requiring removing the entire tank. Any helpful tips? I'm at the point of buying a fuel pump. It sucks not having the full power of a bike already lacking on power but the bike is too dang good of a commuter.

 

[670cc]

I assume it will requiring removing the entire tank. Any helpful tips? I'm at the point of buying a fuel pump. It sucks not having the full power of a bike already lacking on power but the bike is too dang good of a commuter.

I read the service manual on this topic just a few days ago. To the best of my recollection, at a minimum, you need to remove the brackets over the tank at the fuel filler area, which also means removing the side and tail plastics. Then you remove the fuel tank and turn it upside down to get the fuel pump out.

 

[showkey]

There is one more concern ( risk) with replacing the fuel pump with no testing. The pump is just one part of the system. The pressure regulator is a major player which is a separate part.

 

[670cc]

Adding to what showkey wrote, the NC service manual explains how to check the fuel pressure. It does require an in line type pressure gauge, or an inserted fuel line with a T fitting to connect the pressure gauge. Unfortunately there is no test port as found on automobiles.

Given the trouble and expense of replacing the fuel pump, I’d advise testing the fuel pressure first if you can acquire the necessary tools.

 

[thanosgp]

I read the service manual on this topic just a few days ago. To the best of my recollection, at a minimum, you need to remove the brackets over the tank at the fuel filler area, which also means removing the side and tail plastics. Then you remove the fuel tank and turn it upside down to get the fuel pump out.

That is the the right order of labor to reach the pump.I did not test the fuel pressure prior to the motor swap,because there was no test port as you mentione.Lucky enough the swap worked like a charm and i got rid of stalling and heavy vibrations getting a new bike back.Vmax is higher now and acceleration silky.

 

[potter0o]

Fiddling with the gas tank is easier when it has less fuel so plan accordingly with your fueling relative to when you plan to start the work.

 

[Hondafan]

You can do a fuel flow test fairly easily. If the flow is lower than spec, it is probably a restricted filter. On the left side of the bike behind the radiator, you can see a pressure fitting on the fuel line into the fuel rail. Disconnect it. Place the hose end from the tank into a graduated container. Turn the ignition key on and allow the pump to prime into the container ( about 2 seconds). Do this 5 times. The minimum amount of fuel after that procedure is 8oz. I checked mine a few years back and it took about 20 minutes
I have had a few filters on various bikes clog up. Generally the bike will not achieve anywhere near it's top speed, and will cut out if you give it full throttle. A pressure regulator failure, will make the bike near impossible to keep running, and will tend to pop and backfire.
Just keep in mind that you can have high fuel pressure and low flow. Or high flow and low pressure. If you have less than 8oz. of fuel after that test, you definitely need to remove the pump assembly.

 

[MiG Angel]

Do you have heated grips? Have they dislodged at all? Are they in their correct position? ...had a similar situation.

 

[SergeantChuck]

You can do a fuel flow test fairly easily. If the flow is lower than spec, it is probably a restricted filter. On the left side of the bike behind the radiator, you can see a pressure fitting on the fuel line into the fuel rail. Disconnect it. Place the hose end from the tank into a graduated container. Turn the ignition key on and allow the pump to prime into the container ( about 2 seconds). Do this 5 times. The minimum amount of fuel after that procedure is 8oz. I checked mine a few years back and it took about 20 minutes
I have had a few filters on various bikes clog up. Generally the bike will not achieve anywhere near it's top speed, and will cut out if you give it full throttle. A pressure regulator failure, will make the bike near impossible to keep running, and will tend to pop and backfire.
Just keep in mind that you can have high fuel pressure and low flow. Or high flow and low pressure. If you have less than 8oz. of fuel after that test, you definitely need to remove the pump assembly.

Thanks for the suggestions. Since I have changed the injectors, I am familiar with the fuel line location and the removal of the fuel line. If I have time, I will try this today. I do have one question. When I disconnect the fuel line, the existing fuel will drain out. Did you catch that fuel in your container or just the fuel from the test?

 

[SergeantChuck]

Do you have heated grips? Have they dislodged at all? Are they in their correct position? ...had a similar situation.

Are you saying your heated grips were causing the engine to run terribly?

 

[Hondafan]

Thanks for the suggestions. Since I have changed the injectors, I am familiar with the fuel line location and the removal of the fuel line. If I have time, I will try this today. I do have one question. When I disconnect the fuel line, the existing fuel will drain out. Did you catch that fuel in your container or just the fuel from the test?

Start the test with an empty container.

 

[SergeantChuck]

You can do a fuel flow test fairly easily. If the flow is lower than spec, it is probably a restricted filter. On the left side of the bike behind the radiator, you can see a pressure fitting on the fuel line into the fuel rail. Disconnect it. Place the hose end from the tank into a graduated container. Turn the ignition key on and allow the pump to prime into the container ( about 2 seconds). Do this 5 times. The minimum amount of fuel after that procedure is 8oz. I checked mine a few years back and it took about 20 minutes
I have had a few filters on various bikes clog up. Generally the bike will not achieve anywhere near it's top speed, and will cut out if you give it full throttle. A pressure regulator failure, will make the bike near impossible to keep running, and will tend to pop and backfire.
Just keep in mind that you can have high fuel pressure and low flow. Or high flow and low pressure. If you have less than 8oz. of fuel after that test, you definitely need to remove the pump assembly.

Conducted this test last night. After the 4th priming of the pump, I was already over 8 ounces. I don't know what kind of pressure should be coming out of that hose but the flow seemed pretty strong. It wasn't shooting out like a fire hose but it was coming out quickly.

 

[SergeantChuck]

Tried to run a second compression test last night that almost ended badly. I got everything setup and began the test. I spun the throttle handle to the WOT position and started to crank the engine. When the meter reached about 155 PSI, the hose shot out of the spark plug hole with the threaded end still in place. I got lucky and was able to take a narrow set of needle nose pliers and spun out the piece that threads into the spark plug threads. Looks like the father-in-laws gauge has seen better days. One the plus side, it most likely was going well over 155 PSI because it shot off almost immediately.