ZZR1100 Fuel problem?

[1198]

Hi all,

I'm after a little advice about my Kawasaki ZZR1100. It's a C1, 1990 model.
It will start and run but when the throttle is opened, even slightly it packs in, as if there is not enough fuel going in. On that logic I've tried 1. The fuel tap itself. Working fine. 2. Bypassing the fuel relay (straight from the + battery terminal to the fuel pump. No improvement. 3. Removing a pipe from the discharge of the fuel pump. Fuel flowed when the pump was running. 4. I have replaced all the fuel in the tank, thinking it may be old, and added fresh super unleaded. 5. I've tested the fuel pump relay and although it seems to be different to the reading suggested by the manual surely thats irrelevent as the problem exists when it's bypassed.

I have had the tank off recently for a major service (forks out and rebuilt shock, oil, chain, tyres etc and so have had the airfilter box out but can see no obvious pipes or tubes that I've disturbed.

Thanks for your time

Ian

[ricklincs45]

Hi Ian,

when did this problem start? Immediately after the service, or is that just coincidental?

If straight after, something may be amiss after it's all back together. Did you disconnect any electrical connections under there?
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Author '80 Bikes, and counting...' Currently getting frustrated with an MZ 125 TS.

[Fizzer Thou]

It sounds very much as though you have an air leak on the inlet side.If you get the engine running,spray some WD40 around the inlet manifold rubbers and see if the engine note changes.It might be that the inlet rubbers might have perished.I have had this on bikes over a certain age and I replaced some on a Yam R1 not too long ago which had a similar situation.but on my Exup1000 there is an inlet manifold as well as the carb mounting rubbers,and the 'O' rings between the head and the manifolds had shrunk and leaked air just enough to make balancing the carbs a bit difficult.

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/Picture352.jpg
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Just talk bikes.What else is there?

Always have a 'Plan B'

[1198]

I've now got the carbs off, and can see no defects on the inlet rubbers. Surely if one was allowing air in and screwing up that one cylinder the other 3 wouldn't cut? I'm wondering now if a strip of the carbs may reveal some dirt in them, although I struggle to believe that they would all have the problem. The fuel pp, relay and filter seem ok. I've tested them this afternoon. It's driving me to drink!!!

[Casper]

Does the ZZR600 not have this problem if the stupid pipework round the airbox is disconected or plumbed in wrong? the 11 may have the same system.

Another thought is something wrong with your wiring at the switchgear and when you twist you are shorting the kill switch wire.

[1198]

Ill look into the pipe work around the air box idea, it is disconnected at the moment (as is the whole air box) but would this make any difference when the bike is stationary? Surely there will be no pressure difference across the pipe which seems to end (start!) in the centre of the ram air inlet. It won't even rev at all when on the centre stand. Ill certainly look in it more though next week. I did try the kill switch idea too, but can't see anything there either. More beer may be needed!

[1198]

I've had the carbs off and could find no snags. I then tried rebuilding the bike and trying it at each stage. With just the fuel connected and my hand operating the throttle And choke from local (cables disconnected) it ran fine. With the cables reconnected again it ran fine. And finally with the airbox connected and bodywork replaced it still works. I'm totally baffled! I've done a couple of shake down runs (not too long as it was raining!) it's working. As I said, I'm totally stumped. I'm pleased its sorted but wish I knew why it'd happened...