FZ6 power loss and bogging when revved quickly - Help on fuel pump needed.

[Maximokmo]

Hi all,

My first post so Hello everyone, I am from London UK and have a FZ6 600 2006.

I bought it recently with 13000 miles on clock, great condition, previous owner kept it indoors and looked after it. It had been sitting for about 4 months before I bought it. It was riding nicely until one day when I left the tank raised to charge the battery, it developed an issue.
Now, the bike still starts but is a bit reluctant to. It will idle fine but if you open the throttle quickly, it bogs badly and loses power. This can cause stalling especially if uphill. However, if you very slowly raise the revs, it can reach high rpms. See video here: https://streamable.com/lo7lmd

The fuel was syphoned out and replaced with fresh high octane fuel, this hasn't helped. I changed spark plugs, checked TPS and CPS, all fine.

The fuel pump primes when starting but it does seem as if the engine isn't receiving enough fuel under heavy throttle action.

Today I drained the tank fully and removed the fuel pump (see photos of fuel pump filter and the last bit of fuel that came out tank which has a little water and gunk in it).

I don't have much experience with fuel pumps but this feels like it is the issue - it looks rusty and dirty to me. Is this normal levels of rust and gunk or is this excessive?

How can I clean the fuel pump properly? I have read that the filter is difficult to replace alone. Can I soak the whole thing? I have left the tank to dry out properly, should I clean that too? I have bought a bottle of Sea Foam fuel system cleaner, is that worth a shot?

Thank you for any advice in advance!

 

[Gary in NJ]

Welcome to the forum.

That amount of sludge in the filter can certainly cause a fuel delivery issue. When you propped up the tank it probably allowed the sludge to settle in just the right place to cause a problem.

I'd just clean the pump/filter assembly with brake cleaner. I'd also fill the the tank with vinegar and allow it to sit overnight before draining. If the drained solution looks like mud, you'll have to consider coating the tank. If it's mostly clear, you should be good to go.

In the video....what is the cable that is moving with the throttle?

 

[Maximokmo]

Welcome to the forum.

That amount of sludge in the filter can certainly cause a fuel delivery issue. When you propped up the tank it probably allowed the sludge to settle in just the right place to cause a problem.

I'd just clean the pump/filter assembly with brake cleaner. I'd also fill the the tank with vinegar and allow it to sit overnight before draining. If the drained solution looks like mud, you'll have to consider coating the tank. If it's mostly clear, you should be good to go.

In the video....what is the cable that is moving with the throttle?

Hi Gary, thank you for your swift reponse.

Sounds good, I will clean the filter/pump assembly out with brake cleaner.

What kind of vinegar should I use? And should I literally brim the tank up with just vinegar? Or a solution?

The cable is part of the heated grips assembly.

 

[Gary in NJ]

In the US we can get vinegar at the grocery/market with 5% acidity. I would fill the tank to the point where you can see it - that should do the trick. Agitate (shake) the tank a few times over the course of the day. When you empty the tank you'll want to rinse it with water to flush out the vinegar and any remaining rust. When it starts to run clear, add some baking soda to the final rinse to neutralize the acid. If the tank was really rusty you'll want to coat the inside with a light oil, otherwise it will begin to immediately rust again. If it was mostly clear with an easy rinse you wont need any further treatment. When parked for long periods, do so with a full tank to reduce the potential for rust in the future.

If you have access to a boroscope you can view the inside of the tank to see where any potential rust is before (and after) the clean out.

 

[Maximokmo]

Ok thank you for your help Gary, I will keep you updated!

 

[Maximokmo]

Ok time for an update.

I cleaned out the fuel pump and filter as best I could with brake cleaner. I soaked the tank in vinegar for 48 hours then rinsed it out multiple times with bicarbonate and water and then dried it properly with a hair dryer. The tank is now pretty clean with most of the dirt and flakier rust removed. I then refitted the tank and filled it half full with fresh high octane fuel. For the first minute, I thought it was fixed as it would rev properly without severly bogging. A few minutes into a test ride, the original problem slowly returned and now it is running badly again... any ideas?

 

[Motogiro]

Have you checked the fuel pump pressure! it may be okay at first but the start to fail. There is also a fuel pressure regulator with in the pump that can fail.
Also if you've had rust contamination the fuel rail may have particulate that have made it to the injectors.

 

[Maximokmo]

I don't have a fuel pump pressure gauge although that is now on my ever-growing list of tools to purchase for this!
I cleaned the fuel pressure regulator when cleaning the pump and it seemed ok. Maybe it has failed though.
The key thing is this problem only arised from when the tank was left in the upright position for too long. Before that, the bike ran beautifully.
I'm going to run through some seafoam to see if it unclogs and dissolves any rust in the fuel injectors and rail first. Really hoping this helps!

For extra context on the symptoms, the power in the low RPMs is really poor, if I try and speed off at traffic lights, it is really difficult as it bogs so easily unless you use high rpms and use the clutch very slowly. Before this issue, the bike was super responsive and crisp and snappy on the throttle as a bike should be (which makes them fun!).

 

[Maximokmo]

FYI...
Here is video of what the bike sounds like now: https://streamable.com/qzdir6
And here is a video of how the bike sounded before this whole issue started: https://streamable.com/fw6zfz

 

[TownsendsFJR1300]

Most definitly a fuel delivery issue, or lack of...

Did you clean / test the fuel injectors themselves?

Any crap / rust that got into the system would eventually work their way to that point.

.

 

[Motogiro]

Any fuel cleaner will not dissolve rust particulate. It seems like the computer is not recognizing the throttle is open do to a bad TPS signal. It's weird cuz you would think when you open that throttle that wide is would lean out and stall. Instead the computer is keeping the bike running as if it is at and idle.

 

[Maximokmo]

Thanks for the replies, appreciate the advice.

TownsendsFJR1300 - I haven't cleaned the fuel injectors or cleaned them, that is something I am considering trying next if testing the fuel pump pressure reveals no issues.

Motogiro - I have tested the TPS value range in the diagnostics system and it was fine. Is this sufficient to rule out the TPS? Strangely, if you very gradually open the throttle, it will gradually increase revs all the way up to the very high rpms, you can do this when riding too. It seems to be an issue when the throttle is opened quickly. It is also very rough and jerky at low rpms riding in town.

 

[Gary in NJ]

Let’s rule out a clogged fuel vent. Try running the bike with the fuel cap left open.

There are some other FZ6 specific fuel flow failures…like the water jacket at the fuel block…but let’s check the simple things first. The fact that the bike ran well for a minute and then got weird again makes me think a blocked vent line.

 

[Motogiro]

Thanks for the replies, appreciate the advice.

TownsendsFJR1300 - I haven't cleaned the fuel injectors or cleaned them, that is something I am considering trying next if testing the fuel pump pressure reveals no issues.

Motogiro - I have tested the TPS value range in the diagnostics system and it was fine. Is this sufficient to rule out the TPS? Strangely, if you very gradually open the throttle, it will gradually increase revs all the way up to the very high rpms, you can do this when riding too. It seems to be an issue when the throttle is opened quickly. It is also very rough and jerky at low rpms riding in town.

Follow the other suggestions given.
I've had a TPS (automobile) show fine on an ohmmeter but all the symptoms still pointed to the TPS. Changed the TPS and the vehicle ran fine. This told me that the computer takes many samples per TPS sensor position and what we don't see in the DC realm can cause problems in the computer.
Another example would be to have a bad volume control on an audio device. You hear all kinds of static but an ohmmeter will not show it as bad unless there's a really big anomaly.

 

[Maximokmo]

I have just tried with the fuel cap open and that hasn't helped. The bike is back to its worse, struggling to start and really boggy right from the get go. What do you reckon next? I think checking the fuel pressure would be a good idea at this point.

In fact, motogiro if this helps - the bike now often stalls when the throttle is blipped far enough, this may be to do with seafoam being in the fuel mix now though.

 

[Gary in NJ]

Seafoam will not cause the poor throttle response you are seeing. A fuel pressure test is a good next step.

If the fuel pressure is within normal limits, then I would investigate a blockage at the fuel rail where the fuel lines attach. I would also check the fuel lines themselves for a blockage.

 

[Maximokmo]

Currently trying to order a pressure gauge and I'm finding two different types - which one do you recommend?

 

[Gary in NJ]

For a one-time use, I’d get the cheaper one (probably the top kit). The kit in the case is more robust as it has brass fittings and more connect options…and I’m a sucker for seldom use tools that come with a case.

 

[Motogiro]

For a one-time use, I’d get the cheaper one (probably the top kit). The kit in the case is more robust as it has brass fittings and more connect options…and I’m a sucker for seldom use tools that come with a case.

It's a terrible affliction!

 

[Maximokmo]

Update:

Pressure gauge finally arrived. I tested the fuel pressure and was getting a reading of 13 psi, making me think the fuel pump is the problem. I then removed the fuel line (line between pump and rail) and cleaned it out properly. After reassembling, the bike, like a miracle, started running pwell and revving smoothly. It seemed like 90% fixed. Million miles better than before. I was really confused so I tested the fuel pressure one more time, but after reassembling this time, the bike now won't start! It turns over but I think there's no fuel getting through. I have checked the connections and still nothing. I reinstalled the fuel gauge a last time, and noticed that the bike primes, producing a small pressure of about 10 psi, then it drops to 0 once the priming buzz sound ends. Makes me think the fuel pump really is done. I'm going to try source a fuel pump, wish me luck...