Fuel / Pump Issue

[polhovsky]

A fuel issue that is perplexing me. 94 ZX11D. I am the original owner with 14k miles on the bike. I rode the bike religiously when first purchased (this is my 4th Ninja over the years). Since I got married 5 years ago, the bike has been riden, a total of 5 times (maybe). The last time I rode the bike (last summer) that bike barely moved, I had to enable the choke completely to make the bike move. The bike sounded like it was running on 2 cyl's. My rig was running slower than my first 50cc moped. I parked it last summer with the intentions of combing through one day.

That day is today. 20 years ago, I was a mad-man for bike maintenance and storage. Today, 2 kids later, from non-use and my poor attemps to prep the bike for long-term storage, I have a list of negative issues that have created for themselves on my rig. The bike LOOKS showroom, but runs horrible.

Fuel is the obvious one right now. I removed tank to inspect. Can anyone tell me when the fuel pump is to operate? Is it continuous? If I crank the bike I get no activity from the pump. I checked the voltage from the connector and noticed that when I crank the bike it only shows 4-5 volts. If hot wire the pump the battery, it runs and spits out fuel. Is this correct? My first guess was that the pump was dead and the motor was pulling the fuel from the tank (hence having to enable the choke) rather than being supplied by the pump. However, as I mentioned prior, if I hot wire the pump, it works. Can someone out there give me a detailed and specific description on the path of fuel for this bike. NOTE: downloading service manual as I am writing this.

Thanks...Paul.

[cwill]

Almost the same problem with mine.pump does not run constenly.i goes on and off because of a ponits system in the end of it.sounds like you may have fauled out some plugs to why itis only running on a few cyls.put new plugs in it and new fuel.then drive it .I know the pump runs from the starting circut when turning the eng over then comes on from the relay once it startes up.but may be a good idea to relplace the filter too if it had been sitting that long hope this hepls and good luck.

[Hammerhead]

The most common problem with any bike that has sat is clogged carbs. Modern gasoline has a usable life of around 30 days from refinery to combustion chamber. Beyond that,it tries to turn back into a dinosaur bone which does not pass very well through tiny carb jets. Fuel pumps are set to kick off at a certain pressure and it sounds like yours is working. More than likely, the carbs need a good disassembly and cleaning.

[ESCLASS]

I have a similiar problem. Bike would cut off when I opened the throttle...turned out to be the fuel pump relay. Replaced with a used one..lasted 3 months now its out again. Put another ..worked 1 day..now its out again. Only thing I can think of now is that the fuel filter I put in is way smaller than stock causing pump to over work maybe blowing relay or pump itself is going and on the fritz causing the relays to go.

[rossb]

Originally Posted by polhovsky

Since I got married 5 years ago, the bike has been riden, a total of 5 times (maybe). The last time I rode the bike (last summer) that bike barely moved, I had to enable the choke completely to make the bike move. The bike sounded like it was running on 2 cyl's.

I am confident that you have clogged pilot jets. The pilot jets have extremely small orifices and they control the low speed mixture. The choke comment is the giveaway, you are running much too lean and the choke richens up the mixture which allows it to run. Do not continue to run the motor this way. You may also have gunk in your tank, filter, and fuel pump.

Your carbs need to be removed from the bike and cleaned. You do NOT have to separate them from each other, nor should you. You should remove each slide, slide needle, slide spring, main jet, main jet holder, idle jet, pilot jet, float, and float needle. All carb passages should be flushed with gumout and blown out with compressed air. Do not lose any of the spaces on the needle (if you have them, aftermarket jet kits use them) and do not lose the spring, washer, and o-ring under the idle jet. Make sure you count the idle jet turns until seated before you remove it and reinstall it using the same number of turns until fully seated. All parts should go back in the carb they were removed from.

You can get the bike running like a top with a few hours of careful carb work, but they may clog up again if the tank has gunk in it.

[ESCLASS]

As soon as u put the bike in the on position u should here the pump running low. As u turn the throttle the relay gives more juice to the pump. Fuel path is tank to fuel filter..to pump ...to carbs. Change the relay if ur bike only runs with the choke. Relay is clipped right on the battery.

[rossb]

Originally Posted by ESCLASS

As u turn the throttle the relay gives more juice to the pump.

Change the relay if ur bike only runs with the choke.

Huh? Where are you getting your info?

The relay does not have the ability to supply more or less "juice". It is a SPST setup that is either on or off. Changing the fuel relay if your bike only runs with the choke makes no sense. If you really want to test the FP relay just disconnect it and jumper 12V to the relay line that runs to the positive post on the fuel pump. The pump will run and it will turn off after it fills the fuel lines, fuel filter, and the carb float bowls. Disconnect the 12V jumper and start the bike. Your bike will run perfectly for a few minutes until it burns all of the fuel in the float bowls and fuel lines even without a running fuel pump.

If the bike DOES NOT run properly after manually running the pump and filling the fuel lines then you have a carb, ignition, or mechanical problem. If it does run properly after the test, but will not continue to run after you reconnect the relay then you may have a relay or pump problem.

[ESCLASS]

I'm getting my info from what happened to my bike. It ran with the choke on but as soon as I tried to give it gas via the throttle...it would cut off due to fuel starvation cuz the RELAY WAS NOT WORKING. It ran with the choke on and I had to ride home using the clutch (opening slighty to get the bike rolling) and the choke fully open. Now if I am incorrect in the statement that the relay gives more juice..then correct me if I am wrong....but no need to get extra about it. I jumped the power straight to the fuel pump and the pump worked. It was the relay. So it makes perfect sense to change the relay if the bike only runs with the choke. And to top that off it turned out that the fuel filter that I put in which was way too small was overworking my pump and blowing the relay. Furthermore.. The relay can be an SSR (solid state relay) or electromechanical relay which does control voltage levels and is very inexpensive which might be why a brand new one is only 20 bucks. And the fuel pump relay on a zx 11 is a multifunctional one that controls not only the fuel pump but some ignition and other parts..which is specified better in the service manual. How would the fuel pump know when not to suck and pump enough unless it was regulated by the fuel pump relay and current was manipulated by the throttle..which we all know controls the voltage produced by the stator once ur rpms reach a certain pount (on my bike about 3k rpms) which explains why ur lights get brighter as u rev the engine. Now I don't know if its an ssr or emr..but I never had to question that b4 and common sense just led me to believe it was emr for all the reasons I stated earlier (especially since it made sense that revving higher would generate more voltage sending a stonger current to the pump..sucking and pumping more juice...but..I have to call kawasaki now and find out cuz I'm curious. And the throttle and choke have 2 separate butterfly plates or ports into the carbs. On the right side is the choke and the throttle on the bottom center of the carbs.

[rossb]

The FP relay does NOT switch the pump on and off based on RPM or throttle position and it does not regulate variable voltage to the pump.

The FP relay is a standard SPST switch that switches 12V from the 30A main fuse to the fuel pump.

There are 4 terminals on the relay. Two terminals are for the coil (used to energize the relay on and off). The third terminal is voltage in (from the 30A main fuse), the fourth is voltage out to the pump. The relay coil is energized by either the starter switch (when cranking) or an ignition coil (when running). The negative terminal of the relay coil runs to a negative feed on an ignition coil. The positive terminal of the relay coil is split between the starter switch and a positive feed on an ignition coil.

The relay is always energized when the engine is running but the pump itself is able to shut off when the fuel system is fully pressurized, even though the relay remains energized (on).

Changing the relay because the bike only runs with the choke does not make sense. A carb fuel pump does not supply variable pressure values, a port fuel injected pump does. In addition the pump is not going to blow a relay. I base this post on over 15 years experience with the ZX-11 and close to 25 years experience with both carb and F.I cars. There is nothing else I can really add to this thread.

[ESCLASS]

What can I say...I blew 2 relays after changing the filter to the tiny cone filter..then went back to the regular size filter and new relay and haven't had a problem since. I can't explain why 2 relays went bad. And why after replacing the relays the bike ran great. And like I said before...it ran with the choke.

[Claude]

Ross, I know you're right; a relay works exactly like you described it.

[ESCLASS]

So what causes the pump to turn off? If it stops after the float bowls and etc..are filled up.

[zx11norway]

Originally Posted by ESCLASS

So what causes the pump to turn off? If it stops after the float bowls and etc..are filled up.

When everything is filled up,the pressure will build up,and around 1.6-2.3psi the pump will stop.
Nothing to do with relay, in fact many of us has by-passed a faulty relay,and pump still start and stop by pressure.

[rossb]

Originally Posted by zx11norway

When everything is filled up,the pressure will build up,and around 1.6-2.3psi the pump will stop.
Nothing to do with relay

This is correct. The pump is able to turn off by itself when a specific pressure is achived. I am not sure what that actual pressure value is, but carbs typically run with very low fuel pressure. The FP relay stays energized and sends 12V to the pump the entire time the engine is running.

As a test try this:

* Remove the FP relay and jumper the fuel pump 12V input to battery voltage (key can be off).

* The pump will run for a few seconds and then turn off by itself when full pressure is achieved.

As a side note I always pull my fuel pump relay, turn off my petcock, and run the carbs and lines out of fuel before storing it for the winter. The bike will run for about 5 minutes before it runs out of fuel. In the spring when I am ready to ride again I jumper my fuel pump and pressurize my fuel system before starting. The pump will fill the empty carbs and the empty lines in about 4 seconds, then it will turn off. I also pressurize the fuel lines after carb removal/reinstallation for jetting tweaks or a general cleaning.

[96zx11]

I had a similar issue with my 96zx11; I took a trip to OH, the bike died after running 320miles, 40 miles from Dayton. Motorcycle shop replace fuel pump, bike ran fine home. I replaced the fuel filter pickups inside the fuel tank, fuel and reserve filters were dirty. I guess the fuel pump was working overtime and died due to the dirty fuel filter. Now I open the petcock and a rush of fuel comes out, before it was just a trickle.