Hi all,

I have a 2011 ZZR1400 which is currently running badly down on power.

Initially I was losing power under hard acceleration in the higher rev range, and noticed a high pitched whine from the fuel tank after the bike had been running for some time. I pulled and checked the fuel pump and found the filter was clogged. I replaced the lower filter element, but found that I was still having issues with both the noise and the lower power, so replaced the pump and the pressure valve at the same time. After doing this I tested the fuel pump flow rate and pressure and found I was getting the minimum 67ml over 3sec, and 43PSI. However, I am still down on power, and the whine was still present. I replaced the fuel pump AGAIN and found that the whine has now gone, but I am still down on power.

If I do a slow roll on in first gear I'm able to get up to about 10k rpm, but then in second gear it starts to struggle a bit around 8k rpm. If I go WOT from the mid rpm range (6-7k) in either first or second, the bike just bogs down and has no power whatsoever.

Two days ago I was riding it and it was a far hotter day than previously, and I was finding that even part throttle from the mid rev range was causing the bike to bog down - this was happening in all gears.

The bike is mainly stock, it has got aftermarket slipons and a K&N air filter in it, and I was running a PCV map.

So far I have replaced the fuel pump, disconnected the PCV, checked the spark plugs, run through a bottle of injector cleaner checked the air filter and the ram air tubes.

Last night I tested the atmospheric pressure sensor and the air inlet pressure sensor with the bike at idle, both read in spec according to the service manual, and both read the exact same value. I tested the air intake temp sensor the same way and was getting bad readings, so removed the sensor and tested it independently. The sensor tested fine, so I have checked the wiring between the ECU and the sensor plug - which is also OK. I'm guessing I didn't get a good connection when back probing the ECU pin for the temp sensor. I tested the TPS which returned good readings.

I'm starting to run out of ideas here, so would appreciate any thoughts on what to test next. I am going to re-test the fuel pump flow rate and pressure, but I feel like at this stage my problems must be somewhere else, especially given the way the bike behaves when the air temperature is higher.

Cheers
Chris

It sounds like you're not getting the full fuel demand needed at higher RPMs. You are on the right track by checking the fuel pump and the fuel filter. My fuel filter was gunked up and needed replacing, and I wouldn't have known until my bike was put on the dyno when it was discovered the bike wasn't putting out the power at higher RPMs due to a clogged fuel filter. Change the filter and now all is well. If the pump and filter checks out okay the next obvious route is to check all 4 fuel injector's PSI(flow rate).

Good luck!

If the pump and filter checks out okay the next obvious route is to check all 4 fuel injector's PSI(flow rate).

If there's a squeal from the fuel tank after the bike is shut down, that's pretty common. It's the contents of the tank expanding from engine heat. It happens more on a hot day. There may still be factory wax sealant in the fuel tank bleeder tube and it's not venting. I saw a wad of wax under my kickstand one day after a long summer ride and I suppose that was what it was. An aftermarket gas cap/fuel tank ring that vents from the cap should solve that problem. I had a Lightec gas cap and it did not use the factory bleeder hose, just vented out of the filler neck. I never heard a squeal from it ever.

Thanks for the replies.

The squeal was only present with the engine and the fuel pump running. I initially thought it might have been a vacuum issue but I've checked all the hoses and lines, and even did a road rest with the cap open, squeal was still there. This was all before replacing the fuel pump.

I am starting to wonder if the filter built into the housing is at fault now, which probably means a whole new OEM unit.

I am about to retest the pump for flow rate and pressure, assuming that comes back ok, how do I go about testing the injectors? I'm guessing a whole lot of disassembly to start with? Is it possible to get the injectors out without removing the throttle bodies?

Cheers
Chris

* Last updated by: chrispetersnz on 12/7/2023 @ 12:50 PM *

Ok, fuel flow rate is way down. I tried to fill a 3 gallon container, 7.81L, which should take about 350 seconds at the rate 67ml over 3seconds. After 9 minutes it's not full, so clearly something here isn't right.

Will now disassemble the pump and try to back flush and clean the top filter in the housing

Not sure if the 14 has the same fuel pump assembly as the 14R, but the filter in the fuel pump housing is a replaceable item on the 14R.

It is the same pump, but only the lower filter element is replaceable. Due to a period where I wasn't riding and left the tank mostly empty I got a rusty fuel tank, which forced me to replace the filter and pump. There is another filter in the top of the housing which is pressed in.

When I first replaced the pump and filter I didn't rust treat the tank, so have developed the same issue again it seems.

I'm about to take the pump out and try to clean everything then reassemble.

I'm starting to think I need a whole new OEM unit right now, which would also fix my low fuel light that recently stopped working.

Gotcha...It seems that you pretty much got down to the root cause, with some tidying up in store.

The issue is now resolved. I tested the pump with the upper housing removed and had more than ample fuel flow.

I then cleaned the upper filter housing, combination of soaking it in vinegar, degreaser, carb cleaner, blowing compressed air through it. All of that has resulted in a flow rate of 7.81L in about 3.5minutes, which is well in excess of the required rate.

So if you're having fueling issues, check the flow rate over more than 3 seconds, check the lower filter screen, and even test flow rate without the lower screen installed. If it's still bad, clean and soak the upper filter.

If this ever happens to me again I'll use an ultrasonic cleaner on the top element.

Happy to hear that you got it resolved!

Never let a bike sit with a partially empty tank. When mine are going to be sitting over the winter its always full tank with Stabil in it. Never had a problem with84,000 miles on it.

Mad

Yeah, it was a terrible decision to leave it sitting, and was not planned. I injured my wrist and couldn't ride. Didn't even consider filling the fuel tank, then with covid and lockdowns, and babies the bike took a back seat. Definitely won't be happening again.