Thanks for posting the manual diagram and instructions. I agree that a corroded connection at a harness is a likely culprit for the relay meltdowns.

The manual says to check for battery (12v) voltage @ the black wire; my wire is black with a white stripe (the same?). Am I correct in assuming that one is the 12v positive-in from the ignition switch? And the black with blue stripe is the 12v positive-out going to the fuel pump? Based on what I'm reading, those two jumped together bypass the relay circuit.

​​​​​​The blue with a yellow stripe is a ground wire then, is that right? If that's the case I have a serious problem because I'm getting ~12v at the blue/yellow wire, switch on. 🤔

 

On the fuel cut relay, the Black/White is wire they refer to. It starts out Black from the Fuse Box. After it goes through the Engine Stop switch on the right handlebar, it becomes a Black/White wire. You should expect to see 12v here anytime the ignition switch is in the run position and the Engine Stop switch is in the On position too. The Black/Blue wire is the output from the Fuel Cut Relay to the Fuel Pump.

Each time the Blue/Yellow is provided a ground (which is a really short time, like milliseconds), then voltage is output on the Black/Blue wire. At idle speed, 1200 RPM, that output signal is happening 20 times a second. The only place where you could be drawing too much current and melt the Fuel Cut Relay is on the Blue/Yellow wire or the Black/Blue.

Below:
RED highlight is the Black/White wire from Engine Stop switch
YELLOW highlight is Blue/Yellow wire going to ICM and Ignition Coil for cylinders 2,3.
BLUE highlight is Black/Blue wire going over to the Fuel Pump.

 

Awesome details IDoDirt!! Thank you. It's hard to see the wiring diagram on my phone but I'll pull it up on my laptop and take a closer look.

Since there's ~12v coming IN on the blue/yellow wire (switch on/no relay installed), that must mean that somewhere up the line there's a hot wire back-feeding power through it, correct?

I went ahead and jumped the black/white and black/blue wires at the relay harness (see pics). The bike fired up and seems to be stable, at least at idle/5,000RPM revs. I'm going to jump in the saddle and take the F3 around for some quick hops and see how it does. 😎 Then I'll wind it up to 101 on the 101 and, if all goes well, I can take the tow truck driver off speed dial.

​​​​​​p.s. It might not be necessary, but just in case I'm going to take a small fire extinguisher in my backpack so if the fuel pump decides it's had enough of this monkey business and sets itself, me and the bike on fire, I'll at least reduce the damage done.🧯😉

Thanks again to those who responded for the help!!

 

Hey there. One thing to keep in mind with that jumper set up, if your hey is in the on position, your fuel pump will be running nonstop. Not saying not to try it for troubleshooting but just be aware of that.

 

It's not really coming IN, it's only a 12v "potential" that your meter reads. I've updated the drawing a little. If you follow the 12v Black/White wire that supplies the Fuel Cut Relay, you'll also see that it is providing 12v to the ICM and the Ignition Coils. Now, keep in mind that the coils are just that, a coil of wire. The 12v goes into the coil on the Black/White wire and comes out on the Blue/Yellow. Since the ICM has not provided it a ground connection yet, it shows up as a 12v "potential". The ICM is controlling that side of the circuit, by momentarily providing a ground path. When it makes the ground connection, a large magnetic field is generated in the primary winding of the coil. Then when the ground is removed, that magnetic field collapses and induces a really high voltage into the secondary coil of the ignition coil. It just happens that the Spark Plugs are attached to the secondary windings of the Ignition Coil.

 

Whew! I'm going to have to read that a couple times before I really understand the process going on. Thanks for the details and the updated diagram. 👍

An important question: Since the bike is running with just the jumper installed, can I (relatively safely) ride for a while until I am able to do more diagnostics and troubleshooting work to determine the source of the problem? 🤔

I plan on installing a waterproof in-line 5amp fuse in place of the terminal connector that's shoved in the harness now for an added level of protection.

 

You stand a chance of flooding the carbs, but otherwise I think you would fine.

 

The pump doesn't produce much pressure, or at least the OEM one doesn't, so I don't think it will overpower the float needles. But that steady 12v going to the fuel pump may cause it to burn up as well. Would be interesting to replace the jumper wire with an amp meter and see how much current it's drawing. There isn't any specification for it, so would only be for curiosity.

 

Zipped around town with the fused jumper about 10-miles total and put the bike away last night. Got up this morning and did the same to give it another test run and had no problems...👍😁

Merged on the Santa Monica freeway but kept it at a respectable 65mph and made it about 2-1/2 miles before the bike shut down. 🙄 Checked the relay jumper and it was still in place. Checked the fuse and it wasn't blown. Checked the fuel pump and it wasn't pumping. 🤨

I let the bike cool down and after about 45-minutes it fired right up. Limped home on surface streets without any further incidents. I guess you guys were right: the pump apparently cannot tolerate continuous voltage, especially at freeway RPM's.

I'm at a loss here as far as what to do next. Should I try a new/used ICM? Should I try a different wiring harness? Should I set the bike on fire and push it over a Malibu cliff? 🤔

Please advise.

Fused (5amp) jumper installed; upper left above ICM

 

Is that an OEM fuel pump? I'm not sure you ever said that. Ok now I see you said it's a Caltric Fuel Pump. I have an OEM fuel pump someplace, I'm going to put a meter on it and see how it Ohms out.