FZS600 - No power, won't go faster than 50, engine not smooth

[Torque]

Hiya,


My Yamaha was not used for almost 2 weeks, then 2 days ago I've got the parts, replaced some and went for MOT. Everything was fine till today.
I've went back from a trip, it has no power and didn't rev on gear higher than 4k, if you open throttle more than 1/4 it's starts to splutter, but it splutters very gently, like it was planned or ECU programmed.  You just need to give it less throttle and it does not splutter.
It has no power to go on hill higher than few %, also won't go faster than 50mph.
I can rev it without gear till 7k rpm, but the vibration and noise is very bad.

Since there is no magic there can be 2 issues, fuel or ignition, right?


I was trying to remove spark plug cables separately then start engine, but engine runs much worse even If I remove one of them (so I assume that it's not related with just 1 cylinder or 1 faulty spark plugs).


What you think I should check next?


I know that carb sync and valve clearance it's important, but I don't think that such a power drop would happen after 2 days. I will do it in a next few weeks.


I've 4 guesses:
a) Water in fuel (have issues with tank drain pipe, which is blocked right now to not leak), but I don't think that it would happen in a 2 days.
Motorcycle was running well after 2 weeks of resting, so 2 days are not so much?


b) Coil/coils?


c) Fuel pump


d) Is there ECU or something like that to check?


What's your guess and what's the way to check it? I've most of necessary tools and multimeter (to check voltage, resistance etc.)


Thanks guys

[bozboz]

Sounds very similar to when my fuel pump was packing up. Does the pump prime for longer then usual?

[AdieR]

Mileage?

Service history / recent work?

You say you've replaced parts - what were they (ie, is it possible you've disturbed something during the work you've done?)?

You say you pulled the plug leads off - the cylinder you disconnected must have been firing properly (hence why it ran even worse after; if it were faulty, pulling that lead off would make no difference). Have you tried the same with the remaining leads (or, indeed, have you one downpipe cooler than the rest?)?

[Paul]

If it were me I'd:


1) Drain the carb float bowls
2) Drain the tank and replace with new fuel
3) Bypass the fuel pump
4) Bypass the fuel filter


And see if there was a difference.


Assuming there wasn't any difference, I'd clean out the carbs (jets and airways).


And if none of that worked, I'd look at the ignition system.


Which for me, means staring vacantly at the ECU hoping God would miraculously intervene.

[darrsi]

Have you had the tank up/off?
Kinked fuel line maybe, and is the fuel tap switched fully on?

[Deefer666]

Sounds like fuel starvation/tank vacuuming, more than likely kinked breather hoses on the underside of the tank, could be fuel pump or filter

[Torque]

Thanks guys for help.

Mileage?
Service history / recent work?

Mileage 40k+, service history unknown from previous 10k.

You say you've replaced parts - what were they (ie, is it possible you've disturbed something during the work you've done?)?

Just suspension and brake system. Shouldn't affect.
 

You say you pulled the plug leads off - the cylinder you disconnected must have been firing properly (hence why it ran even worse after; if it were faulty, pulling that lead off would make no difference). Have you tried the same with the remaining leads (or, indeed, have you one downpipe cooler than the rest?)?

I've tried all cylinders and all of them works fine (because it works much worse after pulling plug leads off)

Have you had the tank up/off?
Kinked fuel line maybe, and is the fuel tap switched fully on?

No I hadn't last time, however I will double check it.

Assuming guys you point fuel issues, then I will focus on it. It's already dark, but hopefully tomorrow morning if it's not raining I will be able to do something.
Thanks you are insane

[Torque]

It's to dark today to do something, but I've ridden her just to "trace" the issue and noticed that you can exceed the 4k RPM by just pushing throttle to the limit. It splutters very badly, but accelerating, after it exceed 6k-7k RPM it's splutters a little or going smooth (depends on mood).

Tomorrow I will drain all the fuel, then refill with fresh one. If it won't help then I will bypass fuel pump and filter. If it won't help then I will measure resistance of coils. If it won't help then I will get the carbs off and clean it. If it won't help then... I will read all 40+ pages of FZS 600 splutters topic on the forum

[Paul]

I think it's going to be clean the pilot jets out and the fine drillings (airwways).
Which means taking the carbs off I'm afraid.

[Fazerider]

Simple things first: catch the fluid you drain out of the carbs so you can see whether there is water present.. if that's not the problem, check the air intake... a rag left there, for example, can do a good job of strangling the power.


<edit> My guess the pilot jets are clear, if it starts and runs at low speed the problem sounds more like air or fuel starvation.
One check you can do when it's dark is check the plug caps, leads and coils for sparks tracking.

[darrsi]

Do a quick TPS check as well, they make the bike run like shite when they break down.

[Torque]

Ok I've drained old fuel from tank and carbs.
Filter seems to be fine (not blocked), since when I was draining fuel it was going down very fast.
When I've replaced with new fuel, I've switched off then on bike for a few times, so pump could build the pressure. (I could hear clicks).
Checked coils resistance 2,4ohm (both) and pick up coil resistance 199ohm.

When I've ignited bike, it wasn't running smooth for a 2 seconds, then started running fine.
Went for a ride and was suprised, because was running much much better. At the beginning it was still spluterring, but after a mile it was running almost fine. I was trying to push it few times very hard and was going as it should. However after few miles problem was almost the same as it was before fuel change.

I had no idea, then I've checked TPS and saw 10k RPM (which means that angle is wrong). I was trying to adjust it, but my torx key do not have hole inside so I could not unscrew it .
I need to buy this TORX then I will try. Hope that TPS angle it's the only problem.

It seems that it's quite random.

EDIT:
I would like to replace the spark plugs, HT Leads and plug caps, just in case, but it seems that HT Leads are not changeable due to seal in ignition coil, right?

[darrsi]

Ok I've drained old fuel from tank and carbs.
Filter seems to be fine (not blocked), since when I was draining fuel it was going down very fast.
When I've replaced with new fuel, I've switched off then on bike for a few times, so pump could build the pressure. (I could hear clicks).
Checked coils resistance 2,4ohm (both) and pick up coil resistance 199ohm.

When I've ignited bike, it wasn't running smooth for a 2 seconds, then started running fine.
Went for a ride and was suprised, because was running much much better. At the beginning it was still spluterring, but after a mile it was running almost fine. I was trying to push it few times very hard and was going as it should. However after few miles problem was almost the same as it was before fuel change.

I had no idea, then I've checked TPS and saw 10k RPM (which means that angle is wrong). I was trying to adjust it, but my torx key do not have hole inside so I could not unscrew it .
I need to buy this TORX then I will try. Hope that TPS angle it's the only problem.

It seems that it's quite random.

EDIT:
I would like to replace the spark plugs, HT Leads and plug caps, just in case, but it seems that HT Leads are not changeable due to seal in ignition coil, right?

Yep, leads are part of the coils, just trim about 5mm off the cap end to give it a clean up.


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[Torque]

Thanks, I've ordered those caps with and set of plugs: NGK CR9E.

I've adjusted TPS so it shows 5k RPM also I've measured resistance and it starts from 0,8k and goes up to 4,6k. It seems to be that TPS is fine.

After that went for a ride, but bike was running really bad, no power to ride even 30mph.


I've went back and was trying to measure coils resistance on HT leads, I've removed plug caps and was measuring resistance between 1,2 cylinder HT lead and 2,4, but it was inifinite.
Now I've realised that I should measure propably between 1 and 4 cylinder and 2 and 3 (possibly that's the coils configuration). I will repeat that when got new plugs.


EDIT:
I will wait till spark plugs arrive, however my guess now it's ECU or fuel pump.
I don't think that just 2 days when motorcycle was not used, could affect all cylinders. Even if carb jet is blocked possibly only 1 carb and in effet 1 cylinder wouldn't work properly. not all of them.

[Torque]

Measured HT leads on coils, both had 14,6k ohm.
Replaced all spark plugs and spark caps.
Bypassed fuel pump.


Still got the same issue.


I will have 2nd ECU tomorrow, but now it's possibly clear what's wrong -> carbs.


Do you think that removing them, dismounting, using some carb cleaner from halfords and mounting them again should help?


When I remove them is there anything to check, adjust or just clean?

[Torque]

Replaced the ECU. Still it's the same, bike starts like a charm, but adding gas make it die.
Basically I would worry if bike would have enough power to move.


I've detached carbs and dismantled them. All float tanks had some kind of rust at the bottom, but jets looked clear.


What you think my problem could be?


Can you point me to guide how to proper clean the carburetors please?

[CRH]

have you chkd the diaphrams in top of carbs?..ie, for splits or holes etc?....also make sure sliders are moving freely?....

[Fazerider]

This still sounds like fuel over or under supply or air starvation to me.
Are the plugs sooting up? Check the fuel levels in the carbs by opening the drain with a length of transparent tube attached in a "U".
Have you checked the air intake is clear?

[darrsi]

Choke's not stuck in the "on" position is it?

[His Dudeness]

Have you checked the air filter? Sounds like classic symptoms of a badger in the airbox. I'd check the airfilter and if its ok clean the carbs.

[Paul]

Have you tried by-passing the fuel pump and fuel filter yet?

[CRH]

if the sliders are sticking?....that wont help matters!!

[Torque]

have you chkd the diaphrams in top of carbs?..ie, for splits or holes etc?....also make sure sliders are moving freely?....

They are fine, sliders move freely.

Choke's not stuck in the "on" position is it?

They are not stuck. It's fine.

Have you tried by-passing the fuel pump and fuel filter yet?

Yes. Did not help.

Have you checked the air filter? Sounds like classic symptoms of a badger in the airbox. I'd check the airfilter and if its ok clean the carbs.

Not yet. Thanks for advice. Definitely will do it tomorrow.

This still sounds like fuel over or under supply or air starvation to me.
Are the plugs sooting up? Check the fuel levels in the carbs by opening the drain with a length of transparent tube attached in a "U".
Have you checked the air intake is clear?

When I changed plugs. Old were suprisingly clean, so it's like under supply or air starvation?


Assuming:I've dismantled carbs, cleaned with some Halford carb cleaner and screwed them back.
However I was fighting almost 2 hours to fit them on bike and it's f**** hard to me.

First I've spent almost 30 minutes on connecting throttle links.
After that about 1 hour fitting carbs into airbox rubber gums then still did not manage them to fit into engine.
I think also that doing that on the cold evening does not help, since temperature make that rubber not soft enough.

I don't know what's the easy method to do that? Maybe use some soap/oil to fill the rubbers from the inside?


However seeing above advice, will check the airbox when carbs are fitted properly (hopefully)

[dBfazer600]

Had same problem refitting carbs tonight.

I put the support bracket on that holds the coils, fuel pump and filter. I then use minimal amount of carb cleaner sprayed onto metal carbs and used a screw driver to jimmy from the support bracket and it slipped in solidly.

Check that none of the rubber connections are cracked/split and do the everything up tight. after replacing everything I turned the ignition on twice before firing her up. The fuel pump clicked less the second time I primed the fuel. Bike started like a dream and then I adjusted the idle.

I only ran the bike for 5 mins as my water level is lower due to working on the carbs. So in the morning I am flushing the coolant and adding new. I also replaced my air filter with a K&N.

I noticed when I clean my carbs I had a black sooty substance in carbs 2 & 3 and put this down to the U bend filter that I also used carb cleaner on. I did leave this for 7 days to dry out

Hope you get her fixed soon mate.

Daz

PS make sure the you have tightened up the air box

[CRH]

also chk that none of the inlet rubbers are folded in on themselves after you put carbs bk on?..someone on here had that problem?.....plus did you chk those diaphrams?