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Discussion Starter #1
03 636 Fuel Pump won't turn on.


To make a long story short I cannot figure out why my Fuel pump relay circuit will not work. I have replaced the main harness (needed it, due to mice) and installed a new fuel pump. I checked the relay switches for the ECU and Fuel pump using the batt to activate the electro mag and a multi meter to check the switch and they operate correctly. I have no FI codes. The kick-stand switch, the engine kill switch were tested and working. I also replaced the tip sensor !

I then started to check the voltage potential for the relay parts. (see img)
The ECU relay flicks on (I can feel it trigger) and has almost total voltage drop across the BR &BK/Y.
The Fuel Pump relay does not activate, but has 11.85v on either side of terminal R & BR/Y.
The BR/Y go directly to ECU, is my ECU toast? I have searched everywhere I could and I am out of ideas, someone help please!




 

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Hey man if you need a fuel pump for the beast I have a additional one..Ill let it go for 60.00

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Discussion Starter #3
New Fuel pump

I bought a brand new fuel pump, and a new/used ecu on ebay, changed out and still having same issue. So I’ve basically replaced every part in the fuel system and still no dice. Anyone have any suggestions as to what may cause the Fuel pump circuit not to work?


:mad:
 

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Give me till sunday and I'll think about it and post up some ideas/theories. I've got 2 finals tomorrow and can't put much time into it till then. Quick question, are you getting spark?

And I'd start checking the resistance everywhere as well, if you haven't already

Also, where are you located?
 

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Give me till sunday and I'll think about it and post up some ideas/theories. I've got 2 finals tomorrow and can't put much time into it till then. Quick question, are you getting spark?

And I'd start checking the resistance everywhere as well, if you haven't already

Also, where are you located?
I will have time to check these Sat night or Sunday morning. I will post pics and results by sunday night.


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Yes, I just tested everything again. I was a bit off on the diagram I provided (corrections below). I have 4 of the same to swap out with, one for ECU relay and one for the Fuel Pump relay from the old wire harness and two others from the new/used harness I just put in. All of the relays seem to work fine on ECU circuit but not on Fuel pump. Jumping the relay causes the fuel pump to kick on, but just run and run and run (normally it runs for a few seconds and then stops.

I tested each relay and they all seem to test fine. They were tested by providing power and ground from the ECU circuit. Each side was tested for voltage and resistance. On the switch side of the relay I had an average resistance of 100 ohms. Testing for voltage with (lead on ground) I had approx 11.52-11.6V on power and 0.16v on ground side. On the load side of relay resistance with power off was OL and 0.1 ohms with key on. All but one of these relays were very close to each other.

I went back and tested for power a fuel pump See picture below. Upon key turn I got: on red/blk wire 10.75V. On the yellow/red wire I got 0v. ground tested 0.001 ohm resistance(or checking for cont, it beeped). Someone correct me if I’m wrong but the red/blck is power suppy (which it has), black/white is ground and yellow/red is signal?




On the connector red/black connects to black/teal, yellow/red connects to red/white (and has good con straight to fuel pump relay, 0.1 ohms resistance), Black/white is connected to black/yellow (tested good to ground). There is also a 4th wire on the wire harness side brown/black and is connected to what looks like a terminator/blank cap. Both new and old fuel pumps are the same.












I checked the tip sensor and is installed correctly with arrow pointed up.







Tested for spark and ****No spark**** this thing keeps getting worse. :confused:
 

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You do have an ignition and a key right? I ask because there is a resistor in the stock ignition switch that lets the ecu know the bike is being started with a key and not being hot wired.
 

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Discussion Starter #11
You do have an ignition and a key right? I ask because there is a resistor in the stock ignition switch that lets the ecu know the bike is being started with a key and not being hot wired.

stock key/ignition haven't been touched. Is there something else that has a similar load/resistance effect that would cause no spark and fuel pump circuit not to turn on?
 

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stock key/ignition haven't been touched. Is there something else that has a similar load/resistance effect that would cause no spark and fuel pump circuit not to turn on?
If the resistor in the ignition switch has failed you would have the same symptoms.

I don't recall the color of the wire or the voltage, but one of the wires coming from the ignition switch should be a lower voltage then the rest. The resistor in the ignition switch lowers the voltage to the signal wire going to the ecu.

I think it's around 7 volts but that's a total guess.
 

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Discussion Starter #13
If the resistor in the ignition switch has failed you would have the same symptoms.

I don't recall the color of the wire or the voltage, but one of the wires coming from the ignition switch should be a lower voltage then the rest. The resistor in the ignition switch lowers the voltage to the signal wire going to the ecu.

I think it's around 7 volts but that's a total guess.
Copy,

I will check it out this week/weekend

thanks!
 

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Old man Roger's response sounds logical to me, but I really don't know about that particular problem.

You mentioned jumping the relay on the fuel pump circuit, and the pump just ran. Thats what is supposed to happen, so my feeble little brain says that, that particular relay is bad.
If the relay controls the prime, than you have skipped that and went straight to running normally like when the bike is on. Just a thought. Even though you said you have replaced the relays.
 

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Discussion Starter #15
Old man Roger's response sounds logical to me, but I really don't know about that particular problem.

You mentioned jumping the relay on the fuel pump circuit, and the pump just ran. Thats what is supposed to happen, so my feeble little brain says that, that particular relay is bad.
If the relay controls the prime, than you have skipped that and went straight to running normally like when the bike is on. Just a thought. Even though you said you have replaced the relays.
The power is always ava with key on to the fuel pump via red wire, but I never thought to check it with the key off (will do tonight). the yellow/red wire at the fuel pump connects to red/white (and has good con straight to fuel pump relay, 0.1 ohms resistance from pump to relay) and if I jump it (bypass the relay) it works but not proper, just runs and never shuts off like it normally should.

Im going to check the ignition switch out tonight like roger suggested.

something is causing the fuel pump to not receive voltage from the relay. I believe the circuit from the relay is the signal circuit that tells the fuel pump to turn on an off. This is all assuming power is red and black is ground (which both seem to check out fine. red/blk wire 10.75V-low due to uncharged batt from trouble shooting and black has .001 ohm resistance to ground.) no mods, all stock and only 3k mi on bike.

Relays seem to check out fine. what I am thinking is that the other side to the relay goes straight to the ECU (correct me if im wrong), so something else is telling the ECU to not turn the fuel pump system on.
 

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Discussion Starter #17
Don't try to trouble shoot an electrical problem with a dead battery.
It was just low from all the troubleshooting, turning on and off, turning it over and what not.

I was not able to get very far tonight. I cant seem to find anywhere in the service manual the specs of what i should be getting for voltages. normally in there it lists : removal, installation and inspection and state the specs there. It just says see ch 16 for that but there isnt anything in ch 16 for it

I was able to learn from the wiring diagram that the switch operates off of the brown and white wires, however there are 5 different wires going to the ignition switch at the connector.

Blue=12.21
Red=12
Gray=9.53
White=12.39 (is hot on or off) and drops approx .20v when key is turned
Brown=12.25

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I attempted to put it in to dealer mode 1 so see if it would blink any codes and nothing happened. service man states to turn ign switch and ground out diag pin to chassis for mode 1.

______

I also started to look into a few more things the service man instructed.

Interlock system - checked out per service man specs. stated needed 4v or more and got 12v
 

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I know it's ancient history but u ever get any further with this? I'm having same problem after bike was stolen. Trying to get pump to cycle and let me know it's good but also have no spark w/ 4 good coils. New ECU, no new or old codes, scratching my head. Had no tank tumbler or key switch (crackheads) when recovered, so pump may have eaten debris while being joyridden, but i'm stumped...
 

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ANYBODY OUT THERE? Still watching this thread? I am in the same boat as ninjer was/is (hope it's the former). Any ideas would be helpful. Was told by someone who has had the same problem the grey wire from ign. to ECU has to push under 6v or it won't allow spark or fuel. I got it to 5.42 from 9.53 using inline resistors, but i still get no fuel pump cycle???
 

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Thanks everybody. Figured it out. Go me :D
 
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