[BlueLghtning]

No thoughts from anyone?

 

[BlueLghtning]

Intermittent electrical failures are the worst; a hard failure is a gift, now is your chance. Try not to do anything that might make the bike start working again. Do not wiggle any wires or plug/un-plug anything if you can help it.

:evil6:

Here is the SV650 fuel pump relay.

No voltage at Y/B means one of three things:
1. No voltage on O/W, (likely). If O/W is dead then Y/B will be also.
2. The coil inside the fuel pump relay is broken, open circuit, (unlikely). If the coil wire is broken then 12v can not get from O/W to Y/B.
3. The ECM is holding Y/B at ground, (unlikely). This would happen if O/W has 12v (good), the coil is ok, but the ECM is holding Y/B constantly to ground.

Try check to see if O/W (O/W is the ignition circuit wire and should have constant 12v anytime the bike is on) at the fuel pump relay has 12v. Be sure the key is On, Run/Stop switch is set to "Run", bike is in neutral, side-stand in the up position.

Thanks for getting back with me.

I do have 12v at O/W vith the key on and kill switch in run. I just double checked. That's how I was able to jumper O/W to Y/R to hear the pump prime.

I just checked the fuel pump relay between Y/B & O/W prongs and I show about 93.6 ohms with it set on 200 on my meter.

So does that leave me with only an ECM problem that it's grounding out Y/B for some reason? Any other possibilities that could be causing it? The ECM is sitting flat on the bottom of the plastic area that all the wires are tucked into. Could the ECM be getting a lot of vibes with this and causing the issue?

If that is the case, can I do some sort of manual switch to bypass the ECM? In the other thread, you mentioned a way for him to ground out Y/B, but my issue is a little different?

If it is the ECM and I decide to get a new one, what years are compatible with 2008?

 

[BlueLghtning]

93ohm across the relay is good, that means the fuel pump relay coil is ok.

12v on one side to the coil (O/W) but 0v at the other side of the coil (Y/B) means something is holding Y/B low. Basically you are seeing 12v on one side of a "resistor" but 0v on the other side.

Y/B is a single wire direct connection between the fuel pump relay and the ECM. Either the ECM is holding Y/B low, or the Y/B wire itself is somehow shorted to ground.

As a test, try unplug the ECM. If the ECM is what is holding Y/B low then should see Y/B at 12v with the ECM unplugged.

If Y/B does not show 12v after unplugging the ECM then next step try unplug the fuel pump relay, check continuity from Y/B to ground. That will check for a problem short from Y/B to ground.

Funny thing is, if Y/B is somehow shorted (being pulled to ground), either by the ECM or faulty wire, then that should energize the relay and cause the fuel pump to run non stop. The fuel pump in not stuck on, correct?

Correct, the fuel pump is not stuck on. I just hear the relay click when I flip the kill switch with the key on. I was wondering about too after I went back and read how it's suppossed to behave? Tomorrow is a moving day in the RV, so the bike is all packed in the garage so I'll check back tomorrow after we arrive at our new destination and do the next tests you suggest. Thanks again for your help. ccasion14:

 

[BlueLghtning]

93ohm across the relay is good, that means the fuel pump relay coil is ok.

12v on one side to the coil (O/W) but 0v at the other side of the coil (Y/B) means something is holding Y/B low. Basically you are seeing 12v on one side of a "resistor" but 0v on the other side.

Y/B is a single wire direct connection between the fuel pump relay and the ECM. Either the ECM is holding Y/B low, or the Y/B wire itself is somehow shorted to ground.

As a test, try unplug the ECM. If the ECM is what is holding Y/B low then should see Y/B at 12v with the ECM unplugged.

If Y/B does not show 12v after unplugging the ECM then next step try unplug the fuel pump relay, check continuity from Y/B to ground. That will check for a problem short from Y/B to ground.

Funny thing is, if Y/B is somehow shorted (being pulled to ground), either by the ECM or faulty wire, then that should energize the relay and cause the fuel pump to run non stop. The fuel pump in not stuck on, correct?

I double checked the fuel pump fuse and it's good.

I tested Y/B with the ECM unplugged (both plugs), key on, kill switch on and there is still no 12v present at the plug at the relay. I also checked continuity from Y/B to ground in several different places and nothing there either indicating there is a short anywhere? I even double checked I had continuity from the Y/B at the ECM plug to Y/B at the fuel pump relay plug and I do. I even checked Y/B for 12v at the ECM plug and couldn't get it to register anything there?

So where does Y/B get it's 12v from after the battery? Is there somewhere else I should start tracing that down from? It seems I have no 12v at all getting to this wire?

Just as FYI, the bike does also have a TFI Dobeck performance fueler hooked up, but currently have it tuned to where it's not adding any fuel as it was still to rich. I'm not sure this would affect the fuel pump though, only the fuel injector timing? I might actuall go unhook this just to take it out of the equation.

 

[BlueLghtning]

Something is not adding up, but I think the problem is my fault for not being more clear.

When testing for 12v on Y/B the fuel pump relay must remain plugged into the harness when checking voltage (back-probe the relay connector to make contact). If the relay is unplugged then Y/B at the harness will always show 0v.

Image below for reference: Voltage comes through the fuel pump relay coil (O/W -> Y/B). If the relay coil is not present... no voltage.

Correct, the TFI Dobeck should not affect the fuel pump.

Gotcha, I did that wrong then. I'll repeat and report back. Thanks

 

[BlueLghtning]

Hey @TeeRiver. I apologize, but It looks like I was giving you bad info in the beginning and that's where all the confusion has come from. Sorry about that. We might want to start over and get back to the basics and establish where we are.

So first off my title is wrong about Y/B not having 12v. When I was doing my original test with the info I gave in my first post that Y/B had no power, that was without the relay in place. So that makes sense, of course it wouldn't have any power as it gets power through the relay. With out the relay in place, only R/W would have constant power and O/W when the key & kill switch are on. Y/B only gets power through the relay but gets it's control signal from the ECM. For some reason I had in my head Y/B got power from the ECM.

When I backprobe Y/B with fuel relay in place and without the ECM hooked up, I get 12v all the time as you said I should.
When I backprobe Y/B with the fuel relay in place and with the ECM hooked up, I see about .9v for about 3 seconds, then it goes to 12v+ and I can hear a relay click at the same time this change happens. This sounds correct and should be normal. It's during that .9v that the fuel pump should be priming, but it's not.

So let me back up and give some more info on the fuel relay plug and relay.
R/W - 12v constant, even with key off
O/W - 12v with key on & kill switch on only. (Behaves same with with relay in or out)
Y/B - .9v for 3 seconds, then 12v with key on & kill switch on and relay in place. (This should be correct. As mentioned above, I was testing Y/B with no relay and of course it can't get power then, so that was my bad info.

So that leaves the last wire Y/R which is the fuel pump power which should get 12v when everything else is in place. From a previous post, this was written.

- Y/R (Fuel pump power) This is switched power OUT from the relay to the fuel pump. If R/W = 12, O/W = 12v, and Y/B = 0v then Y/R =12 and the fuel pump will run.

So I check and Y/R is definitely not getting 12v when R/W = 12, O/W =12 and Y/B = .9v. It flucutates, but the higest I saw is .54v for that couple seconds. Most times Y/R hovers around .10v - .24v and then drops off to zero after the relay click. So basically the fuel pump is not getting the 12v it needs to prime. That also explains why when I jumped O/W to Y/R, I heard it prime.

So does this point at a relay problem even though the resistance came back good in a previous test? Maybe I can do more tests on the relay if you tell me what to check?

Sorry again about the confusion. You've been a huge help.

 

[BlueLghtning]

The relay can fail two ways: 1) failed coil, or 2) failed contacts.

90 ohms resistance and hearing the relay "click" means the coil (and ECM control) is okay. But if the relay contacts are bad the relay will not pass current.

Does the bike still run if you jump O/W to Y/R? As mentioned before: Be very careful when jumping pins at the fuel pump relay. Accidental connection between O/W (12v power) to Y/B (EMC control output) can fry the ECM pump control transistor.

If jumping O/W to Y/R gets the pump and the bike to run (basically just bypassing the pump relay) then replacing the relay will fix the problem.

If you are still on the road and can not easily get hold of a new relay then it is okay to leave O/W jumped to Y/R, you will be able to ride the bike no problem. The pump will turn off when the kill switch or key are turned off. PosiTaps can be used for temporary connection.

Just as an FYI, I did jump O/W to Y/R and the bike started and ran great. I went for a ride yesterday evening and it was great to be back on the bike. I have a new relay coming to hopefully be the permanent fix. BTW, in shopping for the relay I realized the one that's in there is probably not stock as there are no numbers on it or anything.

TeeRiver, thanks so much for your help and assistance!

 

[BlueLghtning]

Excellent. That confirms the fuel pump and all else with the bike is ok. The "click" means the relay is being commanded, just not being obedient! The new relay should fix the problem.

The best thing about this is the failure went from being intermittent to hard. Hard failures are easy to fix; intermittent failures will drive you nuts.

Yep, I dealt with an intermitent short on a 2004 Vstrom 650 on a trip to AK back in 2006 that kep blowing fuses. When it blew, I'd lose all my guages, and tail light/brake light. It started off intermittent, but finally turned to a hard failue that left me doing 2500 miles with out all the above. When I got home, I found a chaffed wire in the main wiring harness.

It definitely was a blessing this turned into a hard failure to trace it down and I know how to bypass it now if for some reason it ever happens again.

Thanks again! :worship: