Author Topic: Intermittent fault. Bike won't rev past 6000rpm (Read 2779 times)

robbo · « **on:** 26 April 2019, 09:20:19 pm »

This fault first occurred last November. Performing an overtake the bike felt like it had hit the limiter, but with only 6000rpm on the clock. A tad disconcerting to say the least. My first thought was a blocked tank breather, but popping the filler cap didn't solve the problem. I searched through the forum posts and only came across one with very similar/same symptoms. Sadly that bike didn't get fixed over a 6 month period, and the owner gave up on Fazer ownership. I did the relevant TPS checks which proved ok. Although the Pipercross air filter was only 2 years old I replaced it with a new one, a spare is always handy. On riding the bike, the fault was gone.
Wind the clock forward to last Sunday on a breakfast run, full tank of my usual 97 octane, about 30 miles into the ride the bikes pulling like a train. Accelerating out of a roundabout onto a dual carriageway.......the faults back, 6000rpm the involuntary limiter is hit, change up runs fine to 6k then same again. Pull into first layby, pop the tank cap, no rush of air. The fault persists all the way home, even after an hours stop. Change the fuel filter and check that nothings been sucked into the air filter. A quick whizz up the road, bike runs ok, Today did just over 150 miles of mixed riding, with plenty at high revs, bike ran perfectly. I'm not convinced the fuel filter was the culprit as cutting the old one in half revealed nothing untoward.
When the fault manifests itself it happens bang on 6000rpm in any gear, but revs as it should with the clutch in or in neutral. I was told the ability to rev freely in neutral proves the TPS is ok, but don't know if this is true. Obviously no rev counter fault codes are displayed. Naturally a degree of lack of confidence in overtake situations now exists. The one thing that I will try if/when there's a next time, is to not touch the bike, just ride it the following day to see if the fault persists which might prove if it's possibly heat related. Thinking caps on people, answers on a postcard to...... .Thanks in anticipation of some suggestions.

unfazed · « **Reply #1 on:** 27 April 2019, 01:39:12 am »

TPS will not cause that issue.
It could be a loose connection disconnecting due to the vibration at 6000rpm. I had a similar thing years ago on a 400 four Honda, ran fine and sometimes under acceleration over 7000 it would cause the kill switch connector to come apart, then when revs died it started again. Frighting when it happened overtaking a truck. It was only when I started pulling connectors apart I discovered it,

Check all the connection under the tank for corrosion and the left side panel.

Do not rule out the Regulator/Rectifier, 6000 rpm is 1000rpm above the max output limit of the Rectifier/Regulator which sounds like the Ignitor is shutting down due to excessive voltage.

robbo · « **Reply #2 on:** 27 April 2019, 06:58:10 am »

Thanks unfazed, I 've spent some time trawling through the forum searching for similar fault postings. I've been jotting down a list of possibilities and the regulator is high on the list. Red98 had a similar issue with his 600, which if I remember correctly spanned 43 pages and 17 months of trials and tribulations before changing out the regulator. As you know it's very alarming when this type of fault happens, and both times it's been whilst overtaking. In the Haynes manual it says that the regulator can be taken to a Yamaha dealership for "testing". Maybe it would be worth sourcing a replacement as a process of elimination. Thanks for your input, much appreciated.

ogri48 · « **Reply #3 on:** 27 April 2019, 10:16:43 am »

i'd go down that road mate. Even if it aint the reg/rec you got a useful spare. I had a similar prob on a vfr 750 that turned out to be he reg/rec. luckily for me it was such a common fault with them it was the first thing I tried

robbo · « **Reply #4 on:** 27 April 2019, 01:11:45 pm »

A fault on a Honda

.....doesn't ever happen does it?

That's it, a regulator it is then. Just got to decide on genuine from a breaker or a repro one for twice the price.
Decisions decisions, it's never ending.

roxburd · « **Reply #5 on:** 27 April 2019, 07:11:28 pm »

Is it a digital limit? Like a rock-solid 6,000 exactly, like it's an electronic thing that's going on?

Or is it around about 6,000-ish with some wandering up and down?

The former would suggest something digital/electronic whereas the latter something else.

Electric:
The bike uses the wasted spark system, so if one spark plug is failing it could take out two cylinders, giving a 50%+ drop in power?? I've found in the past that replacing the plugs can be a quick and relatively cheap way to fault-find.
Otherwise, I'd say it's more likely to be the ICU then the R/R??

Non-electric:
Have you checked your fuel line isn't crimped?
EXUP closing at 6k for some reason?

Don't know really - just thinking out loud. Good luck!

ogri48 · « **Reply #6 on:** 27 April 2019, 07:42:06 pm »

I had an issue just like it on my thou to do with induction, but I know youve already checked that. The power cable for my garmin has an inline box built in about the size of half a fish finger. It had moved around under the seat and partialy fouled the airbox trumpet. ran perfectly to 6k, then four stroked like buggery and died

ogri48 · « **Reply #7 on:** 27 April 2019, 07:45:43 pm »

re the reg rec, I went new repro route but someone suggested one of a different model (think it was a firestorm) was more resilient (Christ knows why) so I got that, and it never happened again.. Bike was getting on a bit in all fairness

robbo · « **Reply #8 on:** 27 April 2019, 09:55:13 pm »

Roxburd, It's bang on 6k in any gear. Feels exactly the same as hitting the limiter. If you rolled off a touch it would run ok. As the rev counter registers fault codes,exup valve,tps etc I did wonder if I located the single wire between the rev counter and igniter, cut it and rejoin with crimps. If the fault reoccurred I could snap this link apart and see if the bike would run ok with no rpm indication. Changing the clocks was on the list of possibilities for the other forum member who had this problem, but as I mentioned earlier, he'd had enough and sold the bike. This is one scenario where the ability to plug in diagnostics would help.The fuel line was checked when I changed the filter, and the exup overhauled 5 or 6 weeks ago. Plugs are about 2 years old, bike only used April to Octoberish. I'll change the regulator as not too expensive in the scheme of things, but does seem a bit "poke and hope", whereas I much prefer a logical approach. Thanks for your suggestions.

unfazed · « **Reply #9 on:** 28 April 2019, 01:01:59 am »

Just pull the plug at the clocks it will run without them

robbo · « **Reply #10 on:** 28 April 2019, 08:32:58 am »

Quote from: unfazed on 28 April 2019, 01:01:59 am

Just pull the plug at the clocks it will run without them

Excellent, thanks

Red Ceri · « **Reply #11 on:** 28 April 2019, 01:08:19 pm »

Robbo, I've got a complete spare bike if you want to swap out parts to find the faulty one.

robbo · « **Reply #12 on:** 28 April 2019, 01:37:53 pm »

Wow Ceri, thanks for your kind offer. As you can imagine, this is going to be a pita fault if it persists after I change the regulator, and will certainly take you up on your offer. Thanks again, much appreciated. Hopefully see you on the May Day run.

red98 · « **Reply #13 on:** 06 May 2019, 11:07:14 am »

Had a play with this , disconected the regulator and started the bike , result....a stutter at 6000 , pulls through on the stand , not brave enough to try it on the road

......ROBBO , texted you buddy , hope this helps.......

robbo · « **Reply #14 on:** 06 May 2019, 06:34:31 pm »

Thank you so much for going to all that trouble Mr.Red.

Very interesting findings. Bike's run perfectly over the last 2 days, but a regulator change is the next job to do. Have replied to your text, thanks again.

PieEater · « **Reply #15 on:** 06 May 2019, 09:39:51 pm »

Have you checked the Reg/Rec cable block under the left hand side of the tank, it's a weak point that suffers with age / corrosion - http://www.yamahafz1oa.com/eskortsdefectiveconnectorreplacement.shtml

red98 · « **Reply #16 on:** 07 May 2019, 06:38:23 am »

Good point pieman

........when i disconected the reg for the test i had to grip both sides of the connector with some water pump pliers

even then it put a bit of a struggle, bit of corrosion in mine but mines not a show bike and i think it had a hard earlier life , worth checking ROBBO If you havn't already...

robbo · « **Reply #17 on:** 07 May 2019, 10:39:29 am »

Great suggestion PieEater, I'll check that out. I've printed off the article you attached and will do that mod as is a definite improvement on the original plug. Much appreciated, thank you.

robbo · « **Reply #18 on:** 07 May 2019, 09:58:51 pm »

Managed to track down a supplier of the suggested replacement connectors. They come in various amperages and figured 30A would be sufficient. They only seem to come in packs of 10, so will have a spare set if anyone wants to do this mod.

ogri48 · « **Reply #19 on:** 08 May 2019, 11:40:52 am »

had to do this mod on a mates honda shadow. I done away with the connector block, cleaned up the wires, soldered them and heat shrank over the joints to finish off. He said afterwards it must have been a problem for a lot longer than he thought, as his bike ran like a different machine. Good call on picking that up mate...

unfazed · « **Reply #20 on:** 08 May 2019, 05:41:56 pm »

Had to do the connector to the Regulator/Rectifier and Alternator on the 1000 also, see pics. I used Anderson Powerpoles (Torberrys) connectors

robbo · « **Reply #21 on:** 08 May 2019, 07:20:03 pm »

Didn't know which company specialised in the connectors, so just blundered around the net until I hit on the make Dent-de-lion, which looked very similar to the ones in PieEaters attatchment. Hopefully this mod plus a change of regulator will remedy this very intermittent fault.

ram · « **Reply #22 on:** 09 May 2019, 05:19:01 pm »

these are good for vehicle wiring bits and nearby to me
http://www.vehicle-wiring-products.eu/
they do the powerpole ones here:
http://www.vehicle-wiring-products.eu/section.php/159/1/powerpole-connectors