919 fuel pump-ecu HELP! Not for faint of heart - Wrist Twisters
 
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post #1 of 7 Old 09-29-2009, 03:54 PM Thread Starter
Tirone
 
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919 fuel pump-ecu HELP! Not for faint of heart

I've got a 2002 Honda 919, the fuel pump relay is not getting its ground from the ecu. If I ground that wire directly, the fuel pump comes right on. all relays, bank angle sensor, and the on off switch are all good. The guy i bought the bike from says he tried replacing the ecu with a working one, and it still did the same thing. (He later sold it and the guy is still using it today). The bike doesn't have any gauges on it, however he had it running for like 2-3 months without them, then this problem occured, and still no worky. so i guess my question is, what wire goes into the ecu that is then switched over to connect the ground to the fuel pump relay?
Or any other suggestions or ideas would be greatly appreciated. Have all the tools i need, and have already spent about 15 hours on this.
Thanks.
Lucas
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(405)612-7407

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post #2 of 7 Old 09-29-2009, 04:41 PM
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This is a copy of my post addressing this problem. The entire thread can be found in Naked bikes / Helpful topics / Fuel pump troubleshooting.
Quote:
Originally Posted by robtharalson View Post
You're going to have to be methodical here.

First, you will need a digital volt meter and one red and one black jumper wire about 3 feet long with aligator clips on one end and sharp probes on the other.

Second, look up the wiring diagram either in the service manual or in "Wrist Twisters Riders Forum > The Machines > Naked Bikes
Helpful Topics for 919 owners:" About 2/3rds of the way down in "Maintenance/Helpful How-To's" is a wiring diagram which will open in a separate window. I recommend saving it to a file in your computer for future reference. Familiarize yourself with the entire fuel pump control circuit including the pump, relay, fuses, grounds, and the relay control from the ECU. Take notes for reference while troubleshooting.

Here we go

Preparation:
Remove the seat and tail piece. Open the fuse box and check all fuses, then remove the headlight fuse. This will extend battery life during testing. Pull the middle of three relays away from its holder. This is the fuel pump relay, and your primary focus for much of the troubleshooting. With the meter, check for power to and from the 20 amp PGM - FI fuse. It is constantly powered directly from the battery (through the main fuse mounted on the starter relay). In all fuse tests, use the exposed metal lugs at the top of the fuses -- it's why they are there. If there is power to both sides, press on. Do not turn on the key unless directed to do so, then turn it off at the conclusion of each test.
Whenever I say Zero volts (0V), it can be as high as 1.5 V or even a little more unless I indicate otherwise.

Getting to the meat of it:

1-- Turn the key on and check for voltage at the Pink wire in the 22 pin gray connector at the ECU. This is a signal from a zener diode in the ignition switch that acts as an ECU reset. It is there to prevent the ECU from initializing if the bike is hot wired.
**** +11.5 Volts (V) -- Normal. Proceed to #2
**** 0V -- Either a broken wire or a defective diode, Find out which and repair / replace the electrical part of the switch.
**********************************

2 -- Making sure the kill switch is on, turn on the key and with the meter check for power at either Black/White wire going to the fuel relay.
**** +12V -- Cool. The EFI system is powered up. Go to #3
**** 0V -- Pull the engine stop relay (the one nearest the fuse box) away from the holder and check for power to the relay on the Red/White wire.
****** +12V -- The relay is getting power from the PGM fuse. Check the black wire for power.
********** 0V -- A problem in the kill switch or wiring. Fix it.
********** +12V -- The relay is getting power from the kill switch. Check the Red/Orange wire for power.
********** 0V -- The relay is getting a ground from the bank angle sensor. At this point, the relay is getting everything it needs to operate and may be defective.
********** 12V -- No ground from the bank angle sensor. Find out why.
************************************************** *

3 -- Check for voltage at the Brown wire in the connector for the fuel pump relay for approx. 2 - 3 seconds after the key is turned on.
**** +12V -- The relay is providing power to the fuel pump. If the pump does not run, go to #4.
**** 0V -- Check for voltage at the Brown/Black wire in the connector for the fuel pump relay for approx. 2 - 3 seconds after the key is turned on.
******** Greater than 6 V -- There is insufficient ground from the ECU to activate the relay consistently. Possible poor connection or defective ECU.
******** Less than 3 V -- Normal reading. Cycle the key while holding the relay to feel for a click.
*********** No click. The relay coil may be open. Replace the relay.
*********** Click. Possible burned contacts. Replace the relay.
******** Between 3 and 6V -- Bad / intermittent connection between the relay and the ECU. Find and repair.
******************************************

4 -- Tilt up the tank and find the fuel pump / low fuel 3 pin connector. Wrap a clean shop towel around the red jumper's sharp probe to prevent shorting it to ground then clip the red wire's alligator clip to power at the starter relay. Be careful with the probe: it is hot at all times. Leaving the connector plugged together, jump +12 volts to the Brown wire in the fuel pump connector. Do not apply battery voltage to the Brown/Black wire. It may damage the low fuel sensor in the tank.
**** Fuel pump runs -- Poor connection between the relay and the pump. Repair.
**** Pump does not run -- Leaving the jumper in place, ground the Green wire with the Black jumper. Make sure it is securely grounded to the frame.
******** Pump runs -- Defective ground. The main ground for the most of the electrical system is on the right side of the frame near the rear of the tank. Check this for a loose bolt or corrosion. Correct as necessary.
******** Pump does not run -- Defective pump, broken wire between the 3 pin connector and the pump, or gremlins. Replace the pump, repair the wiring, or have an exorcism done (or whatever it takes to get rid of gremlins).

This may all look intimidating, but if you take it one step at a time you'll probably find the problem.
Good luck.

Rob

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post #3 of 7 Old 10-01-2009, 01:55 PM Thread Starter
Tirone
 
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I checked the voltage from the pink wire at the ecu, and i've only got 10 volts, then i ran a 12.06 v hotwire from the ignition switch, and it still didn't work. Is it supposed to have exactly 11.5 volts, for the ecu to reset, or can it have more? becuase it didn't work with the 12.06 v, or the 10 v.
Thanks
-Lucas

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post #4 of 7 Old 10-01-2009, 03:26 PM Thread Starter
Tirone
 
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Just got a new ignition switch and its reading 10.8 volts at the ecu from the pink wire. Too little?

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post #5 of 7 Old 10-01-2009, 03:47 PM Thread Starter
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No sireee its not, bike fired right up!!! That problem stumped the honda shop for 10 hours, and a fantastic mechanic buddy of mine for about 100 hours, plus my about 25 hours.

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post #6 of 7 Old 02-02-2020, 04:33 PM
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Quote:
Originally Posted by VoodooChild View Post
No sireee its not, bike fired right up!!! That problem stumped the honda shop for 10 hours, and a fantastic mechanic buddy of mine for about 100 hours, plus my about 25 hours.
Do you mean the (kee) new ignition switch.

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post #7 of 7 Old 02-02-2020, 10:21 PM
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Quote:
Originally Posted by davidandrewschiff View Post
Do you mean the (kee) new ignition switch.
Just in case you didn't notice, this post is 11 years old. Don't worry, it happens from time to time. Welcome to the board!

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