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03 ZX6R 636

4K views 27 replies 6 participants last post by  Dsmooth 
#1 ·
Fuel pump won’t prime. No sound from fuel pump at all. Best place to buy a new fuel pump?
 
#2 ·
Are you sure it is actually the pump that is bad?
 
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#3 ·
I was doing a coolant flush and all seemed fine. I was on my third time adding in distilled water getting ready to cycle that threw and boom the pump just wouldn’t prime. The gas in the tank was old. When I drained it out it was definitely dirty gas. The bike had been sitting for years. I should have drained the gas first but was being lazy.
 
#6 ·
.3 ohms is almost certainly okay. If you zero the meter and repeat the test, it should read closer to zero.

The important thing is that it goes from a very high resistance between 3&4 with no voltage across 1&2, to low resistance when 12V is put on 1&2.
 
#5 ·
Okay I replaced the pump with a oem unit. I am getting no pump prime checked the relay it was bad. I replaced the relay and still no pump prime. I checked the wires on the bike were the pump would plug into with a volt meter and now I get all 000 across the screen. The bike cranks but no fuel from the pump or prime. I checked the fuses in the little fuse box and all is good I am at a standstill. Any help would be great.
 
#7 ·
with a good relay installed, when 12V is put across 1&2 of the relay you should see 3&4 with zero volts between them. Both pins are at the same potential because they are shorted together.

Without power on 1&2, with the ignition on, you should see 12V on 3, if you have the black lead on the negative battery terminal, and the red lead on 3.

The relay coil between 1&2 will move the contact and create the short when current flows through it.

1&2 would probably both measure 12V with respect to the negative battery terminal..... The required ground is almost certainly supposed to come from the ECU, but it's possible that it comes directly from the pressure sensor on the fuel rail.

The pressure switch at the fuel rail opens, to turn off the relay coil, which opens the link between 3&4 which is supposed to turn off the pump when the rail has enough pressure.

I'm guessing you have disconnected that switch, or there's enough crud on the contacts in the plug that the fuel pump relay isn't turning on.
 
#8 ·
I’ll test the fuel pressure switch. I also have no power to the tip over sensor. I tested all fuses under the seat as well as main fuse. All is good there. I am getting power to ecu but don’t know if that’s working. Not sure how to test the actual ecu.
 
#9 ·
There may be no power on the tip switch that you can measure, follow the instructions in the shop manual to check it. Off the top it's either an open between the pins or a short.... One state is normal, the other means the bike thinks it's on it's side.

A lot of logic signals are actually grounds (active low) to indicate a 'good ' state. Particularly ladder logic type signals. I know that sounds like gibberish, but it is in fact a common design practice. If you can prove a thing by having a short to ground instead of having a 'hot' circuit, it takes less power and that slows battery drain.
 
#10 ·
There may be no power on the tip switch that you can measure, follow the instructions in the shop manual to check it. Off the top it's either an open between the pins or a short.... One state is normal, the other means the bike thinks it's on it's side.

A lot of logic signals are actually grounds (active low) to indicate a 'good ' state. Particularly ladder logic type signals. I know that sounds like gibberish, but it is in fact a common design practice. If you can prove a thing by having a short to ground instead of having a 'hot' circuit, it takes less power and that slows battery drain.
It makes since. So the pressure switch is between 3&4? I am
Not 💯 percent sure I have it located. Is it a certain color or shape?
 
#11 ·
I don't know how many pins the pressure switch will have. Most likely, only one. If the fuel rail is plastic, the switch will need two wires, since it would not be able to pick up a ground through the threads it screws into.

Shop manual should show you how to check it.
 
#14 ·
So the fuel pump relay reads 12v then changes to 0v like it should but still no prime on the pump. The tip over sensor shows no voltage. Does the kill switch effect this or the ignition switch? Maybe the resistor in that is bad? Causing no pump prime?
 
#16 · (Edited)
No voltage coming in(outside pins)? Or no going out(Left and middle pin)?
If no voltage across outside pins do you get voltage from left pin, and your neg meter terminal to ground? If so you have voltage going to sensor, but there’s nothing coming out, I’d have to assume you have a faulty tip over switch if that’s the case. If there’s no power going too the sensor at all it’s time to check fuses, and wire connections from the source to the sensor. ( I’d isolate the tip over switch from the bike, and bench test it with a known 12v source) If it passed the bench test, and you can’t find the fault in the wiring, and you wanted to confirm that this is causing your no prime condition you could then run a fused jumper to the hot side of the tip over sensor and see if the bike will prime. (THIS IS A TEST NOT A FIX, ONLY DO THIS IF YOURE VERY COMFORTABLE WITH WHAT YOU ARE DOING, AS ADDING TEST LEADS INCORRECLY COULD CAUSE DAMAGE TO THE BIKES ELECTRONIC SYSTEMS) Electrical gremlins are extremely frustrating, and you have to be very methodical in your process of elimination. if This is getting beyond your comfort zone, do some reading on diagnosing electrical faults, watch some videos or take it to a pro. I spent months chasing down an intermittent electrical issue on my ZRX, it would start fine and run then would crank and crank and not start. I tried TONS of things, checked switched, checked connections Swapped out batteries, and ecu, (thought it was dying when hot) in the end it was a hidden loose 2 pin connector that went from the clutch switch to the wiring harness, when it was vibrated open no start, when jiggled closed, ran perfect... Long story long... these things can take lots of time and head scratching to find a result.

If that wasn’t the problem and your voltages aren’t in the ranges stated when your checking the left and middle pin (output voltage) do you not get any change depending on tilt angle? Or is it just no output voltage? Again if it’s failing these tests it’s a faulty tip over sensor, and need to replace.
 
#17 ·
I get no voltage at the outside pins and when I do the second test with the positive to the middle pin and ground to the left pin no voltage as well as no voltage when tipping the sensor. All the fuses are good I tested them with the volt meter continuity test. I bench tested the relays even though they are brand new and the work properly
 
#19 ·
Just wanted to give a update since I see no one ever post what they find out was the end issue with there bike. I called a local shop that I know the owner of and told him what was going on with the bike and what I tested and replaced and still no start. He told me load up the bike and stop by after the shop was closed and he would take a look. So I did just that once there we pulled the bike in the shop and he started pulling out the fuses. I told him I tested them and they tested fine. His reply was when you check fuses check them one, twice three times. I said why he said when have you replaced them last and I said I haven’t he said that’s exactly the point. The bike is 17years old. Not even 10 -15min in he found the issue with the Main fuse and the two 15 amp fuse housing were corroded. He cleaned the housing and put some grease in the contact points and put in new fuses. The bike fired right up like nothing ever happened. He tested all the circuits just to make sure everything was in working order and everything turned out fine. So when someone mentions to check fuses do a little exploring and check all parts of the fuses. So I ended up paying in a case of beer 🍺 man I felt like a idiot.
 
#21 ·
Dont feel bad..I watched 2 guys at work spend 8 hours changing a motor 20 feet in the air..then try it..no start. I said...did you check the fuses before you did this..of course. I pulled and checked them..dead. It was a fuse problem..not a motor. 8 hours down the tubes for a 5 minute job...shit happens.
 
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