Engine cutoff at 70+ mph is just marginally frightening

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keithq

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On my way back from a brief trip a week ago, as I was pulling into my drive, the engine seemed to stop/start quickly. On subsequent trips, at speeds over 45-50, it would seem to stop/start where it was as if you had completely rolled off the throttle and then went back to speed. A short lunge and then back to normal.

Heading down for some BBQ with a few other FJR types last weekend, it got worse. Once, I noticed my tach needle go waaaaay up and quiver, before dropping back down as if it was doing the start routine. Another time, the letters ERR flashed across the dash LCD before the engine came back on. At first I thought, well, my cruise control is cutting out. But then while at the BBQ place in Stephenville, the bike would go dead, the radar detector would say 'low voltage' and the Garmin would warn it had lost power.

Since it seemed like it might be due to some electrical issue, I unplugged what I figured was the biggest drain, the Denali lights, from my fuse block under the seat. We diagnosed a low RPM in idle and will check that later (out of town now w/o the FJR). But low idle is not the issue at speed obviously. On the way home, the engine dropped out or everything seemed to turn off multiple times on I-20 at speed. Very disconcerting when there are 18-wheelrs all around and people in massively oversized pickups who want to know why you on that dang bike are not going 89+mph!

Finally reached up and unplugged the radar detector somewhere in Ft. Worth, probably 30 miles from home and the bike ran fine all the way home.

So, apologies for the long post but any collective wisdom would be appreciated. I plan on doing a quick 100 miles this coming weekend with and without the detector running to see if that is the real issue. Note, all my electronics are routed to the Eastern Beaver fuse block *except* the radar, which is plugged into the pocket 12volt.

Keith Quigley
2019 FJR1300A
2021 Yamaha XMax
 

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Check that your connections to the battery are solid.
Check battery voltage (after sitting with ignition off overnight).
Check charging voltage at idle
Check voltage at ~3500 rpm
Get battery load tested
Make sure sidestand switch is not flaky
Check stored fault codes.
What year is the bike? Might want to see if failure can be induced by wiggling ignition switch.
Any anomalies with respect to dash lights - especially high beam indicator and signal lights? (ground spider or other connector)

(I highly doubt it is your radar detector unless it is drawing a LOT of power for some reason - unlikely or it would blow a fuse or cook a wire.)

If you have voltage issues from some of the above tests, you may have to find what's up - stator, R/R, bad ground somewhere etc...

Good luck!
 
++ to "Check that your connections to the battery are solid."
Have had these exact symptoms on a prior bike when the negative battery terminal wasn't tightened down after maintenance. That little bit of intermittent resistance in the electrical system causes mass confusion. First thing I noticed was my headlights dimming/flickering when the idle dropped after engine warmup.
 
That is also a symptom, flickering lights in neutral at a stop light, low idle. Give it a little gas and it steadies out. Will need to check the battery terminals as I was in there not too long ago connecting my fuse block. Maybe one or the other is not tight enough. Good call.
 
That is also a symptom, flickering lights in neutral at a stop light, low idle. Give it a little gas and it steadies out. Will need to check the battery terminals as I was in there not too long ago connecting my fuse block. Maybe one or the other is not tight enough. Good call.
Sometimes, the red vinyl cover for the positive lead gets caught under the screw and makes for a poor connection. I listed connections first because it seemed the most likely given your symptoms and your mention of connecting the fuseblock.
 
That is also a symptom, flickering lights in neutral at a stop light, low idle. Give it a little gas and it steadies out. Will need to check the battery terminals as I was in there not too long ago connecting my fuse block. Maybe one or the other is not tight enough. Good call.
Were you able to identify and resolve the root cause?
 
Realized I never fully answered this one. Finally took all the plastic off and noticed the threaded nut under the positive side was just gone. I must have never tightened it up enough and in riding, it just decided to take a leap. Funny story, called a local Harley dealer near my home and asked their parts department if they had any. They had no idea what I was talking about. Apparently, their batteries posts are threaded so no connecting little nuts. My nearest Yamaha place, Freedom Powersprots in Hurst did however have some. In fact, their parts department just gave me a small plastic bag with several different types of connectors, screws, nuts, etc. Very nice.

So now, I am all tightened up and have good power! Went out for a brief 45 miles ride just before the weather turned too cold (again) here in north Texas. 86 degrees two days ago and it was 34 when I got up this morning.
 
On my way back from a brief trip a week ago, as I was pulling into my drive, the engine seemed to stop/start quickly. On subsequent trips, at speeds over 45-50, it would seem to stop/start where it was as if you had completely rolled off the throttle and then went back to speed. A short lunge and then back to normal.

Heading down for some BBQ with a few other FJR types last weekend, it got worse. Once, I noticed my tach needle go waaaaay up and quiver, before dropping back down as if it was doing the start routine. Another time, the letters ERR flashed across the dash LCD before the engine came back on. At first I thought, well, my cruise control is cutting out. But then while at the BBQ place in Stephenville, the bike would go dead, the radar detector would say 'low voltage' and the Garmin would warn it had lost power.

Since it seemed like it might be due to some electrical issue, I unplugged what I figured was the biggest drain, the Denali lights, from my fuse block under the seat. We diagnosed a low RPM in idle and will check that later (out of town now w/o the FJR). But low idle is not the issue at speed obviously. On the way home, the engine dropped out or everything seemed to turn off multiple times on I-20 at speed. Very disconcerting when there are 18-wheelrs all around and people in massively oversized pickups who want to know why you on that dang bike are not going 89+mph!

Finally reached up and unplugged the radar detector somewhere in Ft. Worth, probably 30 miles from home and the bike ran fine all the way home.

So, apologies for the long post but any collective wisdom would be appreciated. I plan on doing a quick 100 miles this coming weekend with and without the detector running to see if that is the real issue. Note, all my electronics are routed to the Eastern Beaver fuse block *except* the radar, which is plugged into the pocket 12volt.

Keith Quigley
2019 FJR1300A
2021 Yamaha XMax
Had similar issues with Mine and it turned out to be water in the gas. You might want to get some stabil or DryGas and see if that helps.
 
Had similar issues with Mine and it turned out to be water in the gas. You might want to get some stabil or DryGas and see if that helps.
OP already established that his issue was a intermittent battery connection.

Gas needs to be pretty bad to end out with phase separation. With ethyl alcohol in typical E10 pump fuel, it will tolerate a fair amount of moisture before it separates out (up to 0.5% or so). Alcohol-free gasoline will absorb only 0.01% or so before separation so an alcohol-based stabilizer will help. Note: Although E10 is more tolerant of water, it also has a greater tendency to absorb moisture from humid air. Best defence is to get fresh gas from a station with high turnover and keep your tank full.
 
Had similar issues with Mine and it turned out to be water in the gas. You might want to get some stabil or DryGas and see if that helps.
I've experienced water in fuel after buying gas in a remote area small station which I generally avoid - big mistake. However, the option would have been to run out of gas in the middle of nowhere before finding another station.
My experience was sputtering and loss of power after some miles, but not a sudden shut/cut off of engine.
For a sudden cut off, I agree that an electric connection is the likely culprit as already addressed.
 
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