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zx11C fuel pump problem

PostPosted: Mon Nov 03, 2014 8:17 am
by bent axle
G'day All. Got a couple of problems with my '90 zx11C. I left the fuel tap on and 15ltrs of fuel decided to hang out in the engine (and air box and anywhere else it could get to). Fixed all that I hope, but noticed that the fuel pump was some dodgy unit off god knows what. Got a new pump and tried it out before putting everything back together, and no power to the unit when the ignition is on.

As there are no manuals or updates for the c model anywhere I can find I went to the zx10 manual, and it says that the pump only runs when the starter is engaged or when the bike is running. Is this true of the zx11c as well? If so, where is the fuel pump relay located so I can start to check the wiring.

Also, as the fuel was happy to gravity feed itself everywhere via I assume a piece of crap in the needle/seat (cleaned and checked them all, they seem fine now) do I really need a fuel pump or will gravity do the job? My old z1000 chewed twice as much fuel as the zx11, and gravity did that job just fine.

Re: zx11C fuel pump problem

PostPosted: Thu Nov 06, 2014 6:12 pm
by goanna_38
If it's like the D model it won't energise until you hit the start button. Put it on the centrestand, put the sidestand down and put it in gear. Ignition on and then hit start button. Leave the clutch alone. The fuel pump should start pumping straight away and should be the only thing working. This technique is also useful for filling the carb float bowls after a carb rebuild without draining the battery by cranking the engine. If it gravity fed into the carbs then the pump was shagged. I had a D model for eight years and the only reason I turned the fuel tap off was to remove the tank. I bought a second one when I suffered an unexpected Skippy/Ninja interface on the first one and it didn't gravity feed when parked either. Your needle and seats in the carbs were probably leaky as well. Any old K's with a vacuum fuel tap used to be notorious for this sort of behaviour because they didn't have an off position. If the diaphragm stuck open it would fill the engine up.

Re: zx11C fuel pump problem

PostPosted: Thu Nov 06, 2014 9:25 pm
by bent axle
Thanks goanna. Unfortunately the monkey who replaced the original fuel pump with god knows what cut and pasted the wiring so I've got to start from scratch almost, which is why I wanted to locate the fuel pump relay and work forward from there. Good tip re hitting the starter without turning the engine over, I'll give it a go tomorrow and see whether there is power to anywhere.

I also have never turned off the fuel tap in 3 years, and it sat parked with a full tank of gas for over a year. At least one needle and seat had to leak though or the fuel wouldn't have got where it did, so I've already pulled the carbies off and cleaned them all out, they look alright and seem to seal OK.

I'll let you know how I go.