i'm confused about what's going on. so with the key turned to the on position, the fuel pump still isn't getting any juice?

i live in CA, and you can send me your ECM. But i thought you already tested the bike with a new ecm.

 

Correct. With the key in the ON position and the stop switch in the RUN position, the fuel pump DOES NOT prime for the ~2 seconds that’s it should. If I power the fuel pump directly (jump the fuel cut relay) I can start the bike, which means I do have spark AND my injectors ARE firing.

In order for the switch inside the fuel cut relay to close (and allow power to be sent to the fuel pump) the ECM needs to ground this relay. In MY SITUATION, the ECM is not grounding the fuel cut relay. I am not sure why though.

Thanks you so much for the offer!!! Yes I did test a new ECM, but I bought it used and there is the possibility that this ECM has a problem too. Could you PM me your address please? If I cannot fix it this Thursday or Friday I will send the ECM out to you.

Thank you so much!
Ed


Does anybody know any good Honda Motorcycle Technician phone numbers? I wish there was a way to contact the engineering department. They could tell me EVERY reason the ECM would not send a ground signal to the fuel cut relay.

 

aloha i had this same problem,looked thru everything ,replaced everything , went back thru the wiring and kept wiggeling the wires pertaining to that system only to figure out that right at the pigtail for the fuel pump to main harness it had a short in it. dont know if youve fixed the problem but just letting you know. aloha

 

this sounds more likely to be the issue than 2 bad ecu's. crossing my fingers for Squidhead.

 

ok so i just got my bike fixed. i tested all of the same things that you did. it ended up being a bad ground in one of the electrical connectors. it is impossible to find unless you have a multimeter. didn't read to much into the post above but as far as the fuel pump goes the brown/black wire powers the reserve sensor, brown peers the fuel pump. hope you get your bike fixed!

 

Thank you for you input! I will double check this, but I do not think this is my problem. Which wire had a short? the outside brown wire, the middle brown/black wire, or the outside ground wire (should be green/something).

Thanks,
Ed

 

What electrical connector did you find it in? It sounds to me like you might have had the common headlight harness ground problem? IF SO that would prevent your bank angle sensor from working, which would in-turn prevent your engine stop relay from energizing/closing. This would cause you to get no power to the ECU, injectors, ignition coils, fuel pump, exhaust air inject solenoid valve, (and the PC solenoid valve & O2 sensor for California bikes).

I get power to all of these EXCEPT the fuel pump. I am not getting power to the fuel pump because my ECM is not grounding the fuel cut relay. I believe safety features would cause this [ignition switch (pink wire/zener diode), kickstand switch, clutch switch, neutral switch, etc], but I am not sure. I bought a new lower ignition switch piece; it is called the "base, contact" and is PN: 35101-MBW-A11. This houses the zener diode which is part of the bikes anti theft system.


If the bad ground WAS NOT in your headlight sub harness to main harness connection, the which plug was it in? I will check whichever plug you had a bad ground in. I've checked a bunch already, so hopefully this is one I did not check.

P.S. I have a multimeter and a PowerProbe; these two things and the bike's wiring diagram are the only reason I have gotten this far. I pretty much have this stinking diagram engraved into my brain !!!! I wish I was a circuit guru!

 

Forgive my ignorance, but does this not make sense to anyone? In order for the relay to forward the current to its target (fuel pump), the ECM has to ground the relay? Shouldn't it be the other way around? It makes more sense to me that in order to activate the relay, the ECM should be sending it the signal/current.

 

The harness that had the ground in my bike was the harness to the left right by the left air intake tube. It was not with the main ones that are in the center with the rubber flap over them. This might be the headlight harness but might not. It is gray harness. There are two of them up in the front. This one was on the left side.

I have a mechanic book for the F4I. It says if there is no power to the fuel pump that u need to check the 30amp fuse, 20amp fuse, bas, fuel cut off relay, engine cutoff relay, bad ground, or ecu. Im guessing you checked all of these?

 

The ECM does control the ground leg of that circuit. It's a common technique for controlling devices.

A relay is basically a switch that is controlled by an electromagnet. When the electromagnet is turned on, the switch contacts close, allowing power to pass through it. In this case applying power to the Fuel Pump. The electromagnet portion of the relay is provided power via a number of fuses and relays. However it does not turn on because the ECM is controlling the Ground side of the circuit. No ground, no magnet. Controlling the ground side of a circuit reduces the voltages that have to flow around inside of sensitive circuitry.