Could you explain which wire to bypass. I want to try that before retrieving a new relay. Thanks for imput.

 

I'm not familiar with the 900RR that you speak of, however the fuel pump doesn't work that way on a F3. You are correct in that the control line for the Fuel Cut Relay is attached to the Ground line of the coils. It's that line that is being switched between ground and line each time the sparks plugs are supposed to fire. That's why the relay is a solid state relay. An ordinary mechanical relay would not be able to respond quickly enough.

I have to asssume that you're not familiar with how the Fuel Cut Relay is wired into the bike or of it's operation. Here's your opportunity to learn something new. The Fuel Cut Relay, which provides power to the Fuel Pump, does receive pulses (on off signals) that also go to the Ignition Coils. Every time that On-Off signal is received, the Thyrister inside that Solid State Relay passes voltage to the Fuel Pump. Since the Thyrister is turning on and off as fast as your Ignition Coils are providing sparks, your meter does it's best to average the the rapidly changing voltage that is fluctuating between 12v and 0v. Your meter will not read 12v on that line that goes to the Fuel Pump. Here is the information out of the manual that supports my explanation.

 

I don't have F3 diagram at home, but did look at 900 diagram. After looking at what you posted, they are the same. Also noticed that in my post that you quoted I contradicted myself. Fuel pump DOES NOT recieve continuous 12 volts, but it does receive 12 volts from the relay so I stand half way corrected LOL. Your explanation and diagram you posted was excellent! Power to pump is pulsating, but it's one seriously rapid pulse (feeds from both coils which is pretty fast even at idle).
Diagram posted shows how to bypass relay. Jumper wire from black to black/blue will run pump continuously with ignition on.

 

Well, not actually. The Fuel Cut Relay is only attached the the signal line that controls the coil for cylinder #2, and #3. Yes it's fast and because of that speed you don't read 12v with a meter (unless you have a meter that can capture peak voltage). If you look back at the beginning of this thread, Eudabusa indicates that he believes that his fuel pump is not getting the proper voltage. I was pointing out that his readings most likely were incorrect due to limitations in his meter. The contacts in these pumps are notorious for going bad. In fact, I ordered a set today because the ones I replaced last fall on my wifes bike have started exhibiting problems.

 

The F3 only gets signal from one coil wire? Then it is different from 900RR. The RR gets feed from both, which is pretty cool if you think about it. While one wire sends 12v's the other acts as a ground, then vice versa. I shot a video yesterday with test light hooked to 2,3 wire but my phone's camera wasn't good enough to actually show it flashing, just looked like one continuous light.
The F3 must have a dedicated ground going to the relay. That's not very cost effective for Honda to use 2 different relays that do same job.

 

Does the F3 use 3/8" fuel line like the RR? If it does, why not fit one from an RR onto the F3's. No known problems with them. Mine is original pump that came with it in 94. Just a thought.

 

Okay, got to work and there's no dedicated ground for F3 relay. Does the relay cycle when the coil is grounded? It would almost have to. Sorry for all the questions, just wanting to learn.

 

Yes, the ground signal energizes the relay alowing power to pass to the fuel pump. At the same time the coil is energized and builds its magnetic field. When the ground is removed by the ICM, the relay turns off, and the magnetic field in the coil collapses on itself generating a spark.

BTW, what year 900RR do you have? I looked as a later model year wiring diagram and there is no fuel pump on it.

 

Okay, gotcha! This old dog loves learning new things. So if the F3 is getting signals from 1 source and the RR is getting it from 2, the F3 has a longer interruption than the RR. I'd be willing to bet that might be part of the reason F3's have problems with fuel pumps. 900RR's stopped using fuel pumps when engine size went up to 919cc's (1996). Nothing changed between the 2 engines to accomodate it not having a fuel pump. When someone with an older model tells me their pump is gone, I tell them to just leave it off.
Anyone who doesn't understand or isn't familiar with coils, they are super cool! With ignition off, the negative side is grounded. Turn the switch on and it's a constant 12volts. Start bike and it alternates from ground to 12volts. If you have a test light with seperate different light for reverse polarity, try this at night time. Connect the clip to neg. side of 1 coil and the probe to neg. side of the other. Then start the bike. The test light will look like a Christmas tree switching from one light to the other. Mine is red and green and YES, I have waaay too much time on my hands LOL
Thanks for taking time to explain that man. I've been working on these things for a long time and like I said I never get tired of learning something new.

 

That's why I'm here, I love to learn. Well, I love to ride too, and work on them, and fix them up, and....