Kawasaki Vulcan Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
A lil help please.
My 900 custom's fuel-pump doesn't kick on and I can't hear the click from the relay when I turn on the key. I have to push the start button and then I can hear the relay click and the pump starts humming. I bought a used junction box and have the same problem. What sends the signal to the junction box? Or did I just have a lil more of this 2020 bad luck and buy a bad box? :rolleyes: Any help is appreciated.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #3
Thanks! I'm a lil rusty with electronics. When I'm checking the with battery attached to the junction box, do I look at voltage or ohms. Running 12v through it, I can hear the relay click but read 0v through the relay.
 

·
Super Moderator
Joined
·
2,707 Posts
First make sure the battery is fully charged. Do power source first then operating voltage. The fuel pump connector should remain connected while doing these two checks.

Checking the power source voltage (page 3-100). 25 V DC setting on the meter. Connect the negative from the meter to the battery negative post (E in the diagram on page 3-100). Connect the the positive from the meter to the black/yellow wire (D in the diagram on page 3-100). Again it is important to connect to the wires at the fuel pump side of the (B in diagram) connector. Note this in the D connection in the diagram. Turn on the ignition key. Voltage should be 12.8 or higher. If not, then we have to check all they mention.

Checking the operating voltage (page 3-99) at the fuel pump connector near the ignition coils, set your meter to 25 V DC. Then the positive from the meter to the black/yellow wire and the negative from the meter to the black/white wire on the fuel pump side of the connector. Important to connect to the fuel pump wires on the pump side of the connector, NOT the wire harness side. Turn on the ignition key. Should get battery voltage (12.8 volts) for three seconds then should drop to 0 volts. If the voltage does not drop after three seconds we have to check the ECM and the fuel pump relay.

Do these checks and get back here with your results and we will discuss the next procedures. If my explanation is unclear, post back. It is 7:40 pm now and I will be online to 9:00 pm. I will check this post again in the morning around 9:00 am. Together we will fix your bike.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #5
Ok, multimeter reads 12.3v on battery. Source voltage; When I turn the key on I read 0v at the pump. Turn the key to acc and back or hit the start button, the pump starts and I get 12.3v at the pump and the it drops to 0v. Let it set a few minutes and check the operating voltage, 0v until I hit the start button or flip the key to acc and back. Then, it turns on and reads 12.3v and then drops to 0v. It's not 12.8v but the battery is at 98% charged and the voltage reading is the same at the battery and the pump, that could be a discrepancy with my multineter.
 

·
Super Moderator
Joined
·
2,707 Posts
No hitting starter button or switching key to acc. Key only goes from off to on. Power source voltage should stay at 12.8. When it dropped to zero, did you loose connection at the wires? Have to make sure. Redo this test.
Operating voltage is doing what it should. The manual states if the pump doesn’t come on, replace it. Unless the internals of the fuel pump has a separate priming component, I think the pump is just having a signal problem. That is why these two tests are critical in the diagnosis and must be performed exactly as the manual states. Redo this test also. Make sure your meter connections remain in contact during the test.
I am assuming your main fuse, ignition fuses, and battery are good.

Post back you results and then we will continue into checking the fuel pump relay. Thanks.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #7
I won't get to mess with it until late tonight sometime, but I will re-do them. Initially with both tests, turning the key to on I read 0v.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #9
Battery at 100% charge reads 12.67v. I've done both tests multiple times. If the fuel pump does not cut on I read 0v(both tests). If it does come on, I get 12.6v for the source. For the operating voltage, I get 12.6 for a few seconds and then it drops to 0v. Afterward, battery reads 11.9v.
 

·
Super Moderator
Joined
·
2,707 Posts
Okay. Thanks for doing the tests again. When the pump does come on, the power source voltage is constant 12.6, which is good. When the pump comes on and the operating voltage is 12.6 and then drops to 0, which is good. If you definitely had the meter probe connections secure and received no voltage then it is an intermittent issue of no power reaching the fuel pump connector. Let’s check the fuel pump relay next. You have to make some wires with alligator clips on both ends to connect to the battery terminals and then to the specific pin connectors in the relay box. If you are going to the store to purchase the alligator clips, get the ones with the plastic sheathing on them. This will prevent you from accidentally touching the neighboring pins in the relay box and burning something up. Best would be to have one wire red (positive) and the other black (negative).

This check is a two part procedure. First just with the meter and second with the battery being used to power up the relay.
The first check with just the meter is on page 16-84. Remove the relay box as instructed. Set your meter to the omega (Ω) symbol on your meter.
Plug your multimeter probes into the jacks labeled common and DC voltage. Use the black plug for common and the red plug for DC voltage.
Set the omega scale on 20. Now put the meters wires on pins 7 and 8 (look for pin location in the relay box illustration on page 16-86) and look at the reading. Do the same with pins 9 and 10 and look at that reading. Now compare the readings to the ones in the chart on page 16-84. If your meter doesn’t show that symbol let me know what the readings are. If you a 1 or OL then raise the setting on the ohm scale on the meter and recheck.

Now going to test the relay circuit. Hook the positive battery wire you made to pin number 9 and the negative battery wire you made to pin number 10. Now the probes from you meter to pins 7 and 8. Doesn’t matter which probe goes to which pin. Should get a reading of 0 as per the chart on page 16-85.

Know it is a bit confusing. Post back if anything is unclear. If you have meter values or connections questions, take a picture of the meter and post it.

If all these reading end up in order, then will have to check the ignition Switch for an intermittent connection.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #11
Lowest Ohm setting on my multimeter is 200, then 2k, 20k, 200k, 2M, and 20M. I'm assuming 200?
 

·
Registered
Joined
·
12 Posts
Discussion Starter #12
Ok 1st test, meter on 20k ohms gives me OL on pins 7&8 (OL on any setting), and 0.2 on pins 9&10. With battery + to pin 9, - to pin 10 I read 0.00 on pins 7&8.
 

·
Super Moderator
Joined
·
2,707 Posts
Can’t explain why the first test is giving the OL on all settings. Cannot be sure the relay box is good. The second test shows all good. Did by any chance did you check the ECU main relay readings according to the chart on page 16-85?

Want to suggest a couple of quick checks that we should have done before. Get some electrical/cleaner spray and do the kill and start switches. Secondly how old is that battery? Just to be sure would fully charge it and take it down to the auto parts store for a load test. Wouldn’t this be funny if it was the battery all along. 😀

If the battery shows good, reinstall it. Then turn the ignition on and see if the fuel pump primes. If not, shut the key off and wait five seconds and try again. If you do this five to ten times and no fuel pump priming, let’s check the ignition switch. Also, does the FI light and oil light come on when the key is turned to on? Then does the FI light go out in 3-4 seconds?

For a guy who said he is rusty with electronics you are doing great.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #15
Ok, battery is 3 years old. I plan to take it Tuesday to get it tested. This started after installing some speaker pods. I ran the battery pretty low that day, but not dead. So, that has been my thought. I'll do the ECU relay checks Monday afternoon when I get up. I'm working tonight and tomorrow night 12 hour shifts. As for the electronics, I took 2 years of it in high school back in the late 90's. I'll get back to you after checking the battery, the ECU relays and cleaning the switches. Thanks for all your help so far.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #16
Ok, so updates: tested the battery this morning after work, it tested good but barely. Rechecked fuel-pump relay, same results. Checked ecu relays, checked out fine. Tested diodes in the junction box and got some questionable results. Cleaned junction box harnesses, ignition switch harness, start button, and kill switch with electronic cleaner. Tested kill switch, works fine. Turned key on and no pump hum. Tapped the start button and it came on. Ever since that, no matter how long I let it set for a while, its working. I'll try it again tomorrow. Maybe I fixed it?!?! 🤷‍♂️
 

·
Super Moderator
Joined
·
2,707 Posts
Quite possible that you did. Could have been an electrical connection that now is making contact. Consider replacing the battery before it lets you down. I am hoping it is fixed.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #19
So far, the fuel pump is working everytime I turn on the key. My new battery came in yesterday, but I haven't had time to install it. Work keeps me busy! I'll get to it after Thanksgiving. Thanks for all your help.
 
1 - 19 of 19 Posts
Top