NC750x (year 2020)

[Henrik Boensvang 9]

Hi all mechanical minded people,

 

I’ve just installed the accessory socket, the relay kit (and the saddlebag support stay)

 

But now my NC750X doesn’t want to start.

 

HISS is turning off.
Fuel pump runs.

 

When I click the starter button the starter engine turns a couple of times and the engine fires a couple of times but doesn’t sustain.

 

So far I’m suspecting some kind of electrical malfunction. Maybe a sensor?

 

Does anyone have a good idea?

 

Thanks in advance.

[Argyll 1,334]

Sounds like it's a flat battery.

[Henrik Boensvang 9]

Hi Argyll, thanks for writing.

 

I thought this as well, and when I put the battery in the charger it was indeed low. So I gave it the night in the charger. But now I’ve installed the fully charged battery back in the bike and the problem persists.

[Argyll 1,334]

Yes, but if the battery is bad then it will not hold a charge. Your battery charger may suggest that all is well but sometimes it isn't.

 

It might not be the battery that is the issue here but it does no harm replacing it anyway - you'll have to do it sometime.

[Henrik Boensvang 9]

Hi again Argyll, I appreciate you helping me. I’m really a newb with these sorts of problems.

 

I just put the multimeter on the battery poles and it shows 12,7 V with the key in the start position. When I press the starter button it drops to 12,4 V and in the few moments of when the engine turns around by it self the voltage actually goes to 13,3 V.

 

Does that indicate a bad battery? I would be more than happy if it would help to just change the battery.

[Argyll 1,334]

Hard to say without being there.

 

A good engine will produce 14.5v when running so 13.3v whist cranking sounds ok. However, I'd like to know why the battery was drained in the first place - was it due to several attempts to start the bike?

[Argyll 1,334]

You should go through some basic checks.

 

Kill switch ok.

Plug leads correctly attached.

Inspect plugs for signs of fuel.

Open tank filler cap in case of vacuum.

Check for plugs sparking (only if you know how to do this)

Is the fuel fresh? 

 

There are many more things to check but it's a bit pointless without hearing/seeing the start up procedure. Can you post a brief video?

[Henrik Boensvang 9]

Hi Argyll,

 

I’ve tried to upload a Youtube movie of the process. I turn the phone to the backseat as I hoped you could hear the fuel pump running. It does run but you can’t hear it because of a passing car.

 

https://youtube.com/shorts/6gT3yJVML0w?feature=share

[Henrik Boensvang 9]

13 minutes ago, Argyll said:

You should go through some basic checks.

 

Kill switch ok.

Plug leads correctly attached.

Inspect plugs for signs of fuel.

Open tank filler cap in case of vacuum.

Check for plugs sparking (only if you know how to do this)

Is the fuel fresh? 

 

There are many more things to check but it's a bit pointless without hearing/seeing the start up procedure. Can you post a brief video?

 

Kill switch ok.

 - Yes

 

Plug leads correctly attached.

Inspect plugs for signs of fuel.

- Haven’t tried these two

 

Open tank filler cap in case of vacuum.

- I’ve tried this.

 

Check for plugs sparking (only if you know how to do this)

 

Is the fuel fresh?

- Do you think I could drain the tank completely and try with a new fresh tank? Is there a smart way of emptying the tank?

I ran 130 km. On the fuel yesterday without a problem and I have a little over 4 L left.

 

Update - One time I’ve managed to keep the engine running if I kept the starter engine running while giving full throttle, then releasing the starter engine, and just holding the full throttle. It was only “just running”. So no rev’ing.

[Argyll 1,334]

Maybe you are short of fuel?

 

Others with more experience of your bike may have some other ideas if you can wait a while.

[Henrik Boensvang 9]

I appreciate your help, Argyll. Thanks a lot.

 

I suspect I might have dislodged a wire or connector somewhere, but my eye can’t spot it, so if someone knows of an “obvious” wire or connector to check I’d love to hear about it.

 

The problem began after I installed the accessory socket, the relay kit, and the saddlebag support stay. I’ve only dismantled the left side of the bike.

[Argyll 1,334]

Well, that's likely to be worth investigating. Check all your connections, including battery earth.

[Henrik Boensvang 9]

Update - no progress

 

I’ve wiggled all the connections I’ve could get my hands on, but none are loose. The connection from the battery to the engine is also ok.

 

I’ve even taken the right side off to see if anything was out of order there. 

[Grumpy old man 4,682]

Reverse the work you've done, for example disconnect the accessories and the relay. I presume the bike was fine before the work.

[Henrik Boensvang 9]

Hi Grumpy(😄), yea.

 

That’s what I’ve been doing yesterday. I talked with my MC-dealer today and he had a theory that it might be the fuel relay. I’m gonna try to place a fresh one when I get back to the bike.

 

I just think it’s weird that it creates a fuel pressure, but then it drops…

Edited July 28, 2022 by Henrik Boensvang

[Henrik Boensvang 9]

That didn’t work. I’m stuck on start then die motorbike.

 

 

[RC166 698]

When you installed your saddlebags pannier frame kit, you haven’t crushed any fuel or breather pipes near the fuel tank have you? Just a thought.

[Grumpy old man 4,682]

It sounds like the pump is priming fine.

Don't play with the kill switch turn it on and leave it on, use the key, only use the kill switch in emergency. 

When trying to start Don't  twist the throttle it shouldn't need it. 

I'm lead to believe from a post on this forum that the Fuel pump relay and the radiator fan relay are the same, try swapping them but I can't help but think it's something you've disturbed. Have you put the bike back to as it was before you started and clean all the connectors you've disturbed. 

Good luck 

 

[RC166 698]

What make/type of support stay/brackets have you installed? Any photos?

 

I think we all probably agree with Grumpy that something has been disturbed. 

[Argyll 1,334]

Do any of our electrical boffins think that it might be an intermittent problem with the sidestand switch?

[Grumpy old man 4,682]

11 minutes ago, Argyll said:

Do any of our electrical boffins think that it might be an intermittent problem with the sidestand switch?

Perhaps he's disturbed the switch connector?  But does the switch not kill everything, even the starter? Oh! But I do remember a nc700 spinning with no start because of the side stand switch. 

[Henrik Boensvang 9]

Hi all, I appreciate you taking your time to troubleshoot with me.

 

It’s all genuine Honda equipment. I ordered it through my dealer from the Danish distributor.

 

I pulled off the Top box kit and loosened the pannier support stay’s screws that fix the pannier holders in the bottom of the bike. So the support stay is still connected to the passenger foot holds.

 

The only two things that are installed by me are the center stand and the 12 V socket in the plastic (no electrical wires are connected to it).

 

 

I completely agree with Grumpy regarding not touching the throttle. It actually only “starts” without me touching the throttle, but I can only sustain the engine by turning the handle as I show on the last video. This is just something I did for the video.

 

And that’s why it’s weird to me… the engine does seem to catch on.. but then apparently decides not to continue operations.

 

I tried switching the two Fuel pump relay and the radiator fan relay around, but that didn’t do anything.

 

The only electrical things I’ve touched (Intentionally) are:

 

- the battery, disconnected the ÷-pol

- the fuse box, installed the 7,5 amp fuse and the relay for the sub harness

- connected the sub harness to the plug in the frunk, and seen it work.

 

After this, I installed the plastic panels and this placed me in the current situation.

[Henrik Boensvang 9]

2 minutes ago, Grumpy old man said:

Perhaps he's disturbed the switch connector?

Is this the cable on the side stand? I’ve tried to hold in the clutch and the brakes. Shouldn’t that check for that fault?

[Grumpy old man 4,682]

Have you connected the sub harness to the correct plug, have you tried disconnecting the sub Harness and removing the relay to see if the bike starts.

The side stand, is just worth  try.

 

[Grumpy old man 4,682]

I'm lead to believe that the sub-harness plug is hidden behind the panels not in the frunk