1996 VFR750 odd no start - PLEASE HELP!!

Hey guys -

It's been a long while since I posted anything, but I have a problem that I recently encountered that really got me twisted.

In May, I was riding the bike for the first time, and had a LOUD pop under my seat. That pop was my brand new Shorai Lithium Ion battery exploding. It made it 39 miles before shorting internally and bursting it's casing. Summit replaced it with a new one.

The new battery showed up just before I moved to South Carolina, and the bike/battery went into storage mode for the remainder of the summer.

The bike finally made the trip down here, and I finally got some time to get the bike awake again. Except the old girl doesn't want to do anything. I have a naughty suspicion that the battery overloading itself may have caused other electrical issues.

Here's what I got:
1.) New Shorai battery is reading strong voltage, as it should.
2.) Main 30A fuse by the battery is intact, not popped.
3.) All lighting is functional, horn is functional, clock is functioning
4.) Discovered that the 10A 'IGN' fuse was popped. Replaced it with another one, which pops immediately as well.
5.) When the starter button is pressed, NOTHING happens. No click, no starter noise, nothing - it's as though it is not connected to anything.
6.) I jumped the starter relay VERY briefly to rule out the starter motor itself. It made a cranking noise, so it's not the starter.
7.) The neutral light and the sidestand lights were illuminated - but i DID not test their functionality (i.e. confirm lights go on/off as expected)
8.) Regulator/rectifier tested good as per the FSM

I am thinking that the handlebar switch or the starter relay are kaput. However, I don't know for sure. I would also like some more opinions.

I have not had a chance to test the clutch diode, or any other electrical components.

I would really appreciate any inputs and help in this matter.

Thanks!
Matt

 

Number 4 is the dead give away till you find out what is causing the fuse to blow no point in looking any further

 

What Norm said. That fuse is for the fuel pump and starter relay and are connected through the kill switch. That switch would be a good place to start checking.

 

Since my prime suspect was the starter switch, I will check the kill switch, too. I do find it odd that the kill switch would be the culprit, as a failed switch would be unlikely to cause a power surge to pop a fuse, right?

I would think that if there was something wrong with the kill switch, it would simply make a circuit that could not be closed...

 

Usually corrosion is the culprit. It can cause a short, which is what you are looking for. You were already at the relay, so the next vulnerable connections are the two you just mentioned. If they are clean, then you may have a worn wire insulation.

You'll use an ohm meter to find where the power lead is connected to ground, when it should not be. That's a very simple circuit, so it shouldn't take long to find the problem.

 

can you jump the solenoid? but look to the fuse that keeps popping

 

+1 on what Norm said--you got to find the fuse issue before you can do anything else.

 

So what do I check for first, here? Electrical troubleshooting is not my forte.

The fuse that is blowing out is the (5) fuse on the bottom of the picture. I don't know why the uploader rotated the photo.

 

check your kill switch and the starter switch....

 

Those switches are shown on the other fuse--are you sure which fuse is blowing? One fuse (5) is for the instrument panel indicator lights, the other goes thru the switches and supplies power to the coils and the starter relay.

 

You are right it is not the (5) fuse but the other 10A fuse. It is blowing when the ignition is ON and the kill switch is flipped to RUN. The side stand switch turns the indicator on and off and choosing a gear other than Neutral will turn off the green dash indicator. I removed the clutch diode and the starter button assembly for testing later today. The kill switch seems to be functioning, as the power transfer is clearly happening when it is flipped.

The starter relay had continuity across the top two and bottom two terminals. It rattles a tiny bit when shaken, too.

The wiring diagram seems to indicate that the fuel cut relay is the next thing after that fuse. Could it be fried?

Like I said earlier, this is NOT my forte so any help is appreciated and needed.

 

Also, as far as electrical "changes" I have, I just added an in-dash 2 wire voltmeter, tied into the switched power supply from the clock. I do not think this is related. I also have "jumped" the hi beam wire to the low beam wire to keep the low beam on constantly. I do not think this is related since the 20A headlight fuse has been out of the bike while troubleshooting and it worked fine this way last season.

 

OK, the handlebar switches on the right handlebar all check out fine. I took both apart - there was no corrosion, and just some greasy schmutz that I cleaned out, as well as polishing all of the points with an xacto blade. The starter switch has continuity across the headlight terminals, and the continuity is broken when the button is depressed. The starter leads show continuity when the starter button is depressed. The kill switch has continuity when in RUN and no continuity when in OFF. Just for grins, I even checked the brake light switch and that works too.

However, I did check the clutch diode, which I pulled off to take home for testing. It failed the continuity checks that were prescribed in the service manual. Could this thing be popping a fuse? It doesn't even look to be part of the circuit that is involved in the fuse that pops...

So now that I am certain that the handlebar switches are fine, what's next???

 

Ok, that fuse is directly connected the kill switch and the fuel relay. From the kill sw/ it is routed to the NO(normally open) starter sw/. When the starter sw/ is closed (pressed) the power is directed to the starter relay. The fuel relay goes through a 15 second diagnostic mode that powers the pump during that time. It then cuts power to the pump, until it gets a signal from the #4 coil.

If you are not sure how to use an ohm meter, I recommend you pay a visit to Youtube. If you have a fist full of fuses and don't mind parting with them, you can do it the redneck way, by unplugging all the suspected parts and start plugging them back in , one at a time, until the fuse blows again.

The suspects are the kill sw/, starter sw/, fuel relay and fuel pump. The starter relay doesn't really get involved unless the button is pressed, so I would ignore that for now. If done correctly, it should really only cost you one fuse.

* I had not seen post #13 when writing this.

 

Usually, when that diode goes bad, the neutral light will come on, when the clutch is pulled.

 

A bad fuel pump (internal short) can blow the fuse for its circuit. After unplugging, a healthy pump shows about 3 or 4 ohms across its 2 wires.

 

My next stop was to check the fuel pump and it's related relays... The redneck way sounds good to me, but I will use my meter to check the impedence at the pump leads, as Squirrelman points out. I will also disconnect everything fuel related in the back and start connecting it one component at a time until the 10A blows (if it blows).

As far as the clutch diode is concerned, I was pretty sure I was doing the test right and it tested bad. The manual shows that there are three pins - two horizontal and close together, and one vertical all on it's lonesome. With the diode on it's side, and the two close together pins on the left, you are supposed to have continuity from the (+) on the vertical pin to the TOP (-) horizontal pin. You are not supposed to have continuity from the (+) on the vertical pin to the BOTTOM (-) horizontal pin. I did not read continuity in any arrangement of testing, from any pin to another pin, (+) or (-) be damned... But everything on the dash indicated normal - sidestand and neutral indicators functioned as expected.

This pic shows a diode, you can see the two pin/one pin orientation. The pins I refer to as 'horizontal' above are in the foreground of the photo.

 

If that is your diode, then the corrosion could be your problem with the test. Another diode test, on the bike, is that the bike won't start with the clutch pulled, while in gear.

Either way, it is not part of the circuit that is blowing the fuse.

 

That's not mine - I pulled it from the web. My diode (as well as every other electrical connection) has been pretty clean of corrosion.

 

Maybe a shorted ignition coil or bad ignition control module, as it shows that is down-stream of the switch. Look on page 16-2, after the kill switch the +12V runs to the ignition control module and the high side of all the coils.

i'm betting it's the control module since it is the more expensive to replace...