1987 VFR electrics/starting/fuses

Awesome. I'll do that first thing tomorrow morning. Any readings for which I should be looking, or should I just note whether or not I'm getting any resistance between each? Also, should I have anything connected -- battery, starter?

(Probably not, since I'm checking continuity, eh?)

 

You got it, nothing connected. If you could make a list similar to the one I made and note the resistance by each, it will be most helpful. I don't have a schematic, so this is pre-schematic information collection to determine what needs to connect where. Luckily this kind of stuff is not too terribly bad to sort out. I am guessing what happened is that the original plug that attaches to the starter relay failed, so the individual wires were independently terminated. Good thing there is only four!

 

Okay, that didn't take long. Here are the results. A measure of (1) is infinite resistance.

WITH FUSE:
B 1 .03
B 2 .01
B 3 (1)
B 4 (1)

WITHOUT FUSE:
1 2 .01
1 3 (1)
1 4 (1)
2 3 (1)
2 4 (1)
3 4 .01

WITHOUT FUSE:
B 1 (1)
B 2 (1)
B 3 (1)
B 4 (1)

So the only circuits are:
Fused, B-1 and B-2
Unfused, 1-2 and 3-4

 

I should note that terminals 1 and 2 were/are fairly heavily corroded. It was difficult to get a good reading, so I ended up taking a brass brush to them. They could still use a good cola bath, though.

 

Excellent. I'll read back through the entire post and see if I can figure out which wire colors go where. So 1 and 2 are your power leads, and 3 and 4 are the relay leads. Good place to start...

 

Try yellow on 3, green on 4, and the other two wires can go to 1 or 2 (I do not think it matters which one goes where for 1 and 2). If the starter button still doesn't work, try pulling in the clutch lever and try it again. Given what info there is to work with, this might do it.

Edited: Now that I look at your resistance measurements a bit closer, I would have expected "3 to 4" to be at least 3 to 6 ohms. It could be that the relay coil is shorted out... Time will tell.

 

Well, I rewired the fuel pump. Now I'm not blowing fuses AND when I hit the starter button I'm getting a click from the relay, but it doesn't engage the starter motor.

BUT!!!

When I hook a gravity feed to the fuel and start it with a screwdriver:

IT RUNS!

. . .! ! !


As soon as I upload the video I'll post it.

Next step: Figure out how to turn that "click" from the relay into "vroom" from the engine.

 

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://img.photobucket.com/player.swf?file=http://vidmg.photobucket.com/albums/v410/bcox/vfr%20restoration/DSCN5769.flv">

 

The YouTube link:

http://www.youtube.com/v/me2WrhDbkKk

 

If you put a voltmeter on the starter side of the relay (M), with everything connected as it is, it should read 12V (battery voltage) when you push the starter button. If it doesn't, the relay is bad.

Good news! A step in the right direction, anyway.

 

With the multimeter grounded on the frame and the positive lead on the M terminal of the relay:

Ignition ON: .44v
Ignition ON, start button pressed: .53v

Guess it's time to replace the relay after all.

 

Not making up those figures, either. It really does only increase by <1v when the button's pressed. The battery voltage is 11.9v (needs a little trickle charger, I guess).

 

Took the starter relay down to the shop again and it tests perfect. The guy there suspects a ground issue from the button.

Once I solve that I need to get the bike running well. It'll idle if the choke is on full but if I try to give it any throttle it dies.
What's that all about?

 

Well, the best way to test the relay in place is to remove the green wire from number 4, and connect a wire directly from the chassis to it. What the typical Honda circuit usually does is to provide a ground for the starting relay through the clutch switch (clutch lever pulled in), or the the neutral switch.

The starter button provides a positive voltage to the relay coil. So by replacing the green wire on number 4 with a wire directly to ground, you are eliminating the safety circuits as a possible problem.

Try starting it as you normally would. If the starter button still doesn't engage the starter motor with the above test setup, make sure and turn the ignition switch off. Leave the temporary ground wire in place on number 4. Now remove the yellow wire from number 3. Touch a piece of wire (16AWG is fine) from the S terminal to number 3. The starter motor should turn the engine over, but it will not start since the ignition switch is off. This test eliminates the entire starter button and fuse wiring loop.

If that doesn't work, well, what can I say? I would want to know exactly how the shop checked the relay.

 

I did that last night, actually, at the shop guy's suggestion. With 1 and 2 as normal and 3 set to the starter button and 4 to a ground, hitting the starter button results in the motor firing.

Ground problem from the button, perhaps?

 

Next ......your carbs need cleaning if bike only runs on choke


What did you pay for the bike, and does it have all the plastic??

 

I just solved the wiring problem today! The previous owner had replaced the fuel pump at some point and time and had royally knackered the wiring. The fuel pump positive was wired to the taillights, believe it or not, and to the #4 pole as well. I corrected this and, lacking a better, cleaner, easier solution, wired a manual toggle switch for the fuel pump up to my handlebars. After machining a replacement return spring for the start button (the original skittered somewhere across the garage floor), everything's good and I buttoned it up.

For fuel issues: It does only run on choke. I will probably take apart the carburetors tomorrow and give them a thorough cleaning. Thankfully I have a little more experience with carbs than I do with wiring, though I'm still a little unclear on some issues. After all, don't they say that "carburetor" is Latin for "don't f*ck with it?"

Squirrelman, I paid $200 for the bike. It has most of the plastics but is missing the lower front fairings.

 

Not the button. This is telling you that there is power all the way through the circuit, up to the point of where the circuit should find a ground. The ground SHOULD be provided by the transmission being in neutral (neutral switch) OR the clutch switch (clutch lever being pulled in). I seem to remember there being a diode after the starter relay and before the two switches. The only older schematic I have is for an '83 CB1100F, but Honda has always been pretty consistent. I'll check it and see what I can find.

Did you try starting it with the clutch lever pulled in, green wire attached to 4?

 

What happened is that the previous owner had done some really ridiculous stuff to the fuel pump wiring.

Basically, the g/r wire was spliced to fuel pump positive. Fuel pump positive was ALSO spliced into the taillights (I'm not kidding). I think this was to start the pump with ignition, but I'm not sure. In any case, this was (obviously) shorting the system.

I cleaned up the wiring and ran new fuel pump wires; instead of dealing with trying to find exactly where the fuel pump should go after all the splices courtesy the previous owner, I wired up a manual toggle switch.

Now I need to work on fueling. I managed to (finally) remove the venturi but I think the carbs will require some elbow grease to remove.

 

I'm late to post on this thread, gave it a quick read...just joined VFR world. I'm pretty familiar with these circuits. Near as I can tell, Lgn knows what he's talking about. You did ask about the fuel pump original wiring? Honda likes to use a fuel cut relay on their non injected bikes that use an electric pump. This device has four wires, one from a fused source, one to the fuel pump...these two are usually black and/or black/blue. Another wire, usually yellow or solid blue goes to the ignition system via the coil. The fourth is a solid green ground. When the engine turns over and produces spark, a signal is sent to the fuel cut relay via the yellow wire, only then will the fuel pump be connected to its power source. That's why on this style of system the pump doesn't run until you hit the starter button and the engine spins. Also note if you don't have spark...your fuel pump won't power up either. I suspect this cut relay failed at one point (or someone thought it did), prompting a previous owner to attempt to "hot" wire the fuel pump. Hope that answers it.