Engine Randomly Cutting out

[Jakeoster]

Hello, I’m having this problem with my 03’ VFR800 non ABS model where the bike runs and idles perfectly fine. Then seemingly at random it simply dies. Sometimes it will start again without having to pull over, sometimes it does not and I have to coast over to the side of the road to restart it. It has led to a couple hair raising moments. 

 

Ive searched around and found a number of different things but I’m not sure where to begin diagnosing first. 

 

I’d like to get it sorted out because as it is, I’m fairly reluctant to ride the bike. 

[Grum]

Hi Jakeoster.

Sympathise with you - Not a good situation to be in.

 

Do you get any flashing error codes from your Fi Light? Can you hear the fuel pump prime every time you turn on your ignition? Are you hearing any relay buzzing noises? Is there ever a situation where the starter Doesn't crank the engine over?

 

Have a good look at the state of your two 30a fuses A and B. Check for any discoloration or burning of the fuse connections.

You may also have a bad earth connection via the Blue Connector for the front of the bike, this can cause issue for the Engine Stop and Headlight Relays, see the site for adding a ground wire to the Green Wire of the Blue Plug.

Check your battery connections are tight.

Also measure your battery charging voltage with engine running should be around 13.5 to 14.5v.

Download the service manual and look at the Circuit Diagram to make sense of the above.

Lets know how you get on. Good Luck.

Cheers.  

[Jakeoster]

Hello, thank you for posting! 

 

FI Error Codes: None that I’ve seen

 

fuel pump priming: Can’t recall it not priming

 

relay buzzing: Can’t say I’ve heard anything 

 

starter: whenever I start the bike it always turns over. Although once when it died, I recall there was a bit of delay on getting it started again. At the time I thought maybe the kickstand spring was weak and maybe the kickstand switch deactivated and shut off the bike. Occasionally if I haven’t rode in a while it’ll take an extra push of the starter to get it to fire up. 

 

I have the FSM downloaded already so I’ll take a look at what you suggested. 

 

Cheers!

 

 

[Jakeoster]

It may have to do with the wiring harness you mentioned. I remember a month or so ago when I replaced the oil/filter/coolant and had the fairings off, I found it odd that section of harness had a label on it that said “made in China”. 

 

Fuses and battery connections appeared to be ok.

[Grum]

You will have to have a good look at your earthing situation.

In the front of the bike is an Earthing Block. It's yellow and has a whole heap of green earth wires going to it, poor connections in this block has caused lots of issues and the block can discolour from high resistance joints. The idea is to solder all these wires together and ensure there is a good ground to them all.

 

The other earth fault is on the blue connector Green wire. On the Green wire of this connector, the side that leads to the front of the bike, you need to splice in another wire onto it and properly Ground this wire to frame. Cut the insulation around the wire, solder a wire to it then ground the other end.

 

Also have a good look at the Fuel Cut and Engine Stop Relays for operation, good connections, and wiring as well as the Bank Angle Sensor.

 

Have a good look at your whole wiring harness for any visible signs of abrasion or cuts into the wiring harness.

When the bike dies, are there any strange issues with Headlights not working, blinkers or instrument lighting?

Another thing you could try with the front cowl off and access to all the front wiring is to Start the bike then start flexing and moving cables, tapping relays etc. to see if that kills your engine, you may just stumble onto the problem that way.

 

A thing to keep in mind that up front of the bike are Three Critical Items - The Bank Angle Sensor, Fuel Cut and Engine Stop Relay. BOTH Relays must be energised for Engine ops, and a fault with any of the three will kill your engine. The Kill Switch could also be an issue However an activated Kill Switch will inhibit your Starter from cranking and that's not happening.

 

Also make sure there is nothing intermittent or faulty with your side stand switch and its wiring. Probably easiest to check this one first.

 

Good Luck

Cheers.

[Jakeoster]

This weekend I’m going to go out and ride until it dies again so I can get a detailed report of what happens. It’s hard to recall because it’s a frantic moment when it happens. But this time I’ll be on the look out. Just watch lol, this time it won’t do it just to mess with me hahaha. 

 

Then I’ll begin the process of dismantling the bike and take a look at what you’ve suggested. I’ve also got speed bleeders to install and a digital manometer to sync the starter valves while I’m at it anyway. 

 

This gremlin will be purged one way or another, and I will return to VFR riding nirvana 

[Grum]

Good one Jakeoster. I like your positive attitude, yes there are plenty of members who could also chip in with help for you. Look forward to hearing what you may find. Agree, when a VFR is on song it's a fantastic machine. Isolate that Side Stand Switch first.

Good Luck.

Cheers.

[Jakeoster]

Thanks! 

 

Apologies, it took a little while to replicate the problem. 

 

Can confirm that the instrument cluster and electrics do not cut out when the engine dies. I can then start the engine as normal after. 

[SweViffer]

On 2018-01-19 at 2:31 AM, Grum said:

You may also have a bad earth connection via the Blue Connector for the front of the bike, this can cause issue for the Engine Stop and Headlight Relays, see the site for adding a ground wire to the Green Wire of the Blue Plug.

 

Just pitching in here. The owner of the problem bike is located in the USA, so the bike should have been fitted with the upgraded front harness during a recall. Check to see if it actually has, otherwise there is new bits to add to the bike that could cure this. Any american with specific knowledge may pitch in here to correct me, but if I recall correctly the shield with the frame number should have a marker punched into it if the recall have been done.

 

Edit: Forgot to add that the quoted fix is not relevant when the recall have been done, since that wire is cut and the earth rerouted elsewhere.

[SweViffer]

My guess would be a partially corroded kill switch, but the relays previously mentioned are also worth having a look into. Good luck! :-)

[Grum]

4 hours ago, Jakeoster said:

Thanks! 

 

Apologies, it took a little while to replicate the problem. 

 

Can confirm that the instrument cluster and electrics do not cut out when the engine dies. I can then start the engine as normal after. 

So are you saying the engine just dies, you pull in the clutch or select neutral hit the starter button and the engine starts?

OR. Do you always have to turn the Ignition OFF then On again to start it? Does the starter Always crank when starter button is pressed? Listen for the Fuel Pump Priming every time without fail when the Ignition is turned ON, make sure this is happening.

Does the engine stop instantly (loss of ignition) OR cough and splutter a bit then dies(loss of fuel pressure)?

Does it ONLY ever die when riding, has it ever died while just idling?

 

Need to get as much info as possible about when it happens, what the indications are and just exactly what's required to start it again. There's plenty mentioned above to check, however with a more detailed description of exactly what's happening might help to zoom in on a specific faulty item.

Cheers.

 

[Terry]

The sidestand switch can also cause these sorts of issues, I'd check whether it is properly attached at the pivot, and the wires and connector are in good shape. 

[Jakeoster]

On 1/27/2018 at 4:53 PM, Grum said:

So are you saying the engine just dies, you pull in the clutch or select neutral hit the starter button and the engine starts?

OR. Do you always have to turn the Ignition OFF then On again to start it? Does the starter Always crank when starter button is pressed? Listen for the Fuel Pump Priming every time without fail when the Ignition is turned ON, make sure this is happening.

Does the engine stop instantly (loss of ignition) OR cough and splutter a bit then dies(loss of fuel pressure)?

Does it ONLY ever die when riding, has it ever died while just idling?

 

Need to get as much info as possible about when it happens, what the indications are and just exactly what's required to start it again. There's plenty mentioned above to check, however with a more detailed description of exactly what's happening might help to zoom in on a specific faulty item.

Cheers.

 

 

Hello, 

 

when the engine cuts off, all I have to do is pull in the clutch and start it. Don’t have to turn off ignition or anything. Instrument panel is still on and functional. 

 

As an aside, I synced the starter valves today and what a difference. The bike is so smooth now, no more lurching or bucking when trying to change gear while riding. Was thinking of getting a Power Commander before to smooth it out, not anymore!  

[Grum]

55 minutes ago, Jakeoster said:

 

Hello, 

 

when the engine cuts off, all I have to do is pull in the clutch and start it. Don’t have to turn off ignition or anything. Instrument panel is still on and functional. 

 

As an aside, I synced the starter valves today and what a difference. The bike is so smooth now, no more lurching or bucking when trying to change gear while riding. Was thinking of getting a Power Commander before to smooth it out, not anymore!  

 

Well, if you just pull in the clutch and it starts, then that means the Side Stand Switch might be OK otherwise the starter would not crank over.

Suggest you start looking at the above recommendations and see how you go. There is plenty of info for you to start checking. Good Luck.

[Jakeoster]

On 1/27/2018 at 2:10 PM, SweViffer said:

 

Just pitching in here. The owner of the problem bike is located in the USA, so the bike should have been fitted with the upgraded front harness during a recall. Check to see if it actually has, otherwise there is new bits to add to the bike that could cure this. Any american with specific knowledge may pitch in here to correct me, but if I recall correctly the shield with the frame number should have a marker punched into it if the recall have been done.

 

Edit: Forgot to add that the quoted fix is not relevant when the recall have been done, since that wire is cut and the earth rerouted elsewhere.

 

 

Hello, I have heard about this recall and checked on Honda’s website. It appears there is no open warranty claims on my bike. The harness on the bike has yellow tape bars on it, leading me to believe that it has been replaced. 

[Jakeoster]

Is there a trick to removing the engine cut off switch from its half clam shell housing? I fidgeted for a while trying to wrangle it out. Looks to be held up on a small plastic tab. Hesitant to give it too much force and break it as I looked in a few OEM parts catalogs and it’s not clear if they sell a replacement. Seems you can get the lower part with the engine starter switch, unsure if that includes the kill switch or not. The whole assembly is listed as item #13 in the OEM parts catalog but there’s no part # listed for it. 

 

I’ve looked in the FSM, no mention of removing it. 

[Grum]

5 hours ago, Jakeoster said:

Is there a trick to removing the engine cut off switch from its half clam shell housing? I fidgeted for a while trying to wrangle it out. Looks to be held up on a small plastic tab. Hesitant to give it too much force and break it as I looked in a few OEM parts catalogs and it’s not clear if they sell a replacement. Seems you can get the lower part with the engine starter switch, unsure if that includes the kill switch or not. The whole assembly is listed as item #13 in the OEM parts catalog but there’s no part # listed for it. 

 

I’ve looked in the FSM, no mention of removing it. 

 

Have you done an electrical check of the Kill Switch? If you have the circuit diagram of your bike, you could check the operation of the switch at the connector it plugs in to. If you have a multimeter simply set it to the minimum ohms range or buzzer continuity mode and probe the two wires for the switch, activate the switch numerous times to verify its operation. As stated before, if the Kill Switch goes faulty you will NOT be able to crank your bike nor will you hear your fuel pump prime!!!!!!!!!! You don't appear to have this situation. SO, do you really need to replace this switch?

 

Have you checked the integrity, both mechanically and electrically of your Side Stand Switch, verify this up to the ECM input? Have you checked that ALL your frame Grounds and the Ground Block in the front of the bike are all Good? Verify the Fuel Cut and Engine Stop Relays, sockets and wiring are all good. If it was my bike this is what I would be looking at first.(assuming you have had a good look at the two main 30a fuses and wiring).

Cheers. 

[Terry]

On 1/29/2018 at 7:44 PM, Grum said:

 

Well, if you just pull in the clutch and it starts, then that means the Side Stand Switch might be OK otherwise the starter would not crank over.

Suggest you start looking at the above recommendations and see how you go. There is plenty of info for you to start checking. Good Luck.

AFAIK, for the starter to run, you need a continuous ground path. That would be through the neutral switch (in neutral) or if not in neutral, through the clutch switch AND the sidestand switch (stand up). So you can start in neutral with the stand up or down, or in gear with clutch pulled in AND the stand up. 

 

If the bike HAS to have the clutch pulled in to start in neutral, I'd suspect the neutral switch or diode may be dodgy, but that doesn't rule out an intermittent fault from the sidestand switch. It would not be a big deal to bridge the sidestand 2P connector (i.e. create a permanent ground path) and ride the bike like that and see if the fault re-occurs. That does disable the interlock system so one could potentially ride off with the stand down...that can end badly at the first left hander as I found out in my youth before sidestand switches became a thing.

[Grum]

3 hours ago, Terry said:

AFAIK, for the starter to run, you need a continuous ground path. That would be through the neutral switch (in neutral) or if not in neutral, through the clutch switch AND the sidestand switch (stand up). So you can start in neutral with the stand up or down, or in gear with clutch pulled in AND the stand up. 

 

If the bike HAS to have the clutch pulled in to start in neutral, I'd suspect the neutral switch or diode may be dodgy, but that doesn't rule out an intermittent fault from the sidestand switch. It would not be a big deal to bridge the sidestand 2P connector (i.e. create a permanent ground path) and ride the bike like that and see if the fault re-occurs. That does disable the interlock system so one could potentially ride off with the stand down...that can end badly at the first left hander as I found out in my youth before sidestand switches became a thing.

Hi Terry.

Thanks for chipping in, good to get some other heads involved. Agree with your logic, simply shorting the Side Stand switch wires is another way of isolating the switch, you could also do the same for the Kill Switch purely for fault finding! 

 

I gather that he is able to start the bike in both modes Clutch in, SS up, and in gear as well as the normal neutral start. Agree that the neutral switch and blocking diode will effect the Start logic but not kill the engine once running. When running the critical info to the ECM is the ground sourced from the SS Switch.

Cheers.

[daved]

I had similar symptoms on my  800Fi, turned out to be a faulty engine stop relay, swapped it with the fuel cutoff relay(they are the same) and the problem changed from total shutdown to slow down, would also mean the bike wouldn't start sometimes(no fuel pump priming noise) 

[Grum]

On 28 January 2018 at 11:53 AM, Grum said:

Does the engine stop instantly (loss of ignition) OR cough and splutter a bit then dies(loss of fuel pressure)?

 

4 hours ago, daved said:

I had similar symptoms on my  800Fi, turned out to be a faulty engine stop relay, swapped it with the fuel cutoff relay(they are the same) and the problem changed from total shutdown to slow down, would also mean the bike wouldn't start sometimes(no fuel pump priming noise) 

 

 Thanks Daved. Exactly why I asked the above question but NO answer. Looking at the circuit diagram it looks like all four Relays - Engine Stop, Fuel Cut, Hi and Low beam are all the same.

Cheers.