Please help a dummy

[Zilla500]

I went out to jump and start my 1991 GS500 yesterday, and the engine would turn but not start. I didn't realize I was running out of gas, and eventually did, but kept turning the engine. After a while, the engine won't even turn over anymore. Did I burn out my starter, or perhaps my coil? I'm about to troubleshoot it, base on the manual, but I could use an initial direction. Thanks! (Please don't laugh

[Nber1LouFan]

I went out to jump and start my 1991 GS500 yesterday, and the engine would turn but not start. I didn't realize I was running out of gas, and eventually did, but kept turning the engine. After a while, the engine won't even turn over anymore. Did I burn out my starter, or perhaps my coil? I'm about to troubleshoot it, base on the manual, but I could use an initial direction. Thanks! (Please don't laugh

ummmmm, is your battery dead? lol

[Zilla500]

I see lights, so no. Also, like I said, this is happening "while" I'm jump starting it with another car running.

[Homer]

Here we go again...lol

[Zilla500]

Yeah I read the forum before asking. In my case, I don't hear any clicks anymore, so I'm not even turning the starter. There can only be three issues with this correct? 1) Battery, 2) starter coil, 3) starter motor. Since I'm jump-starting it, 1) is eliminated. Since I see lights, 2) is eliminated. So that only leaves the starter? Is this correct logic?

[ojstinson]

Just a caution, Don't jump start your bike from a car with the engine running, the increased voltage from the car's alternator could cause severe damage to your electrical system----maybe that's your problem.

[pandymai]

check your fuses and hope they blew before anything else got fried from the excess current of the running car.
and yes, to reiterate, you shouldnt jump a bike with a RUNNING car, the car's battery alone should suffice in power.

[Zilla500]

In the starter circuit, there's only one fuse, the one next to the starter coil, correct? That fuse is good since I see lights when I turn the key. Any other fuses that come into play when starting the bike?

I'll remember to not have a car running when I jump start next time. Thanks!

[burning1]

Zilla, if you no longer hear a 'click,' it's possible that your starter relay is toast.

If I were you, I'd start by picking up your multi-meter and testing for voltage at the starter relay, the trigger lines from the starter switch, and the starter motor. Then I'd check resistance across the starter motor. Keep in mind that you shouldn't run the starter for more than 15 seconds at a time.

[Homer]

Don't even need to do that, actually.  Just jump the relay at the posts, bypassing the starter button/switch and the relay itself.  
Make sure it's in neutral, by the way...  (Which could be your problem, entirely....)
Just brush a heavy-gauge wire across the posts and listen.  

Edit:
if the starter doesn't bump over, then try tapping it with something.  Or unplug it from the relay and use jumpers.  Someone else will have to tell you which wires.  
If it's bad, ask SlimKlim to sell you the extra one I gave him.  

[sledge]

Starter motors and relays have an intermittent rating, they are designed to run/operate only for a few seconds at a time. If you have been letting the motor run and run without giving it a chance to cool down then yes.....its quite possible you have burnt it or the relay out. Get your nose on them, if there is a strong sweet and sickly smell then its fugged.

Its very unlikely the electrical system will have been fried by the donor battery because....
A) The voltages in both are the same ie 12v.
B) Despite the fact the donor battery/alternator can deliver far more current than the bike can the bike will ONLY DRAW as much current as it needs.

[ojstinson]

We are not talking about current here Sledge we are talking about voltage, a car's alternator can put out 16 volts or higher when charging, and this increased voltage will force more current through the bike's system than it is designed to take. Think of voltage as water Pressure on a hose, higher pressure = more water flow or current as it were.

[Toledo Jim]

Okay, an age old question:

Which way does voltage flow?  + to -,  or, - to + ?

[sledge]

2 things OJ

First I have never heard of a vehicle alternator delivering 16v, as far as I am aware the inbuilt voltage regulator every self-exciting alternator carries will limit voltage output to between about 13.5 and 14.8v to purposely prevent overcharging and the situation that you are suggesting might occur. However just because I have never heard of one that can output 16v it doesnt mean they dont exsist. Perhaps you could elaborate and provide me with some specs for such a thing.

On the subject can I ask you why if automobile electrical systems regularly see 16v (thats a 25% increase) it does not seem to harm the various bulbs and sensitive electronics they carry or cause the battery to overcharge?

Secondly with regard to your claim regarding an increase in current. Can I suggest you refresh yourself on Ohms law, particularly for current. You will find it states that in a DC circuit if power remains constant and voltage increases, current DECREASES, not as you claim increases.

Example:

Ohms law states Current (I) = Power (P)/Voltage (E) or I=PxV

So lets try the sums with a hypothetical load of say 100 Watts at both 12v and 16v

At 12v... P/V .....100/12.....= 8.3Amps

At 16V....P/V.......100/16......=6.25Amps

As you can see in the 16v circuit the current is lower by over 2A and from this it would seem to me you have something back to front in your sums.

Incidently this is the reason why some large comercial vehicles run 24v systems, it reduces current flow in the system, which in turn allows for thinner gauge wiring and smaller alternators which has cost and weight benefits.

It is true that components can be damaged by over large over-voltages, however, exposure to say 14.8v for the few minutes it takes to carry out a jump start is very unlikely to harm them.

[ojstinson]

AHHHH, free at last, now we can finally jump start our bikes from the car with the engine running without fear of damaging anything---I feel as though the weight of the world has been lifted from my shoulders.

[Zilla500]

I suspected the starter relay first; I remember my 1995 Ford Explorer having an intermittent non-start/no-click issue and shorting the starter relay would alleviate the symptom. I hope it's this since it'll be a cheaper fix.I'll try to short it to see if it at least turns over.

I don't think the "jumping it with a running car" was the issue here. Oh yeah, it's in neutral - I'm not that kind of a dummy yet.

[Zilla500]

Right after I typed my last reply, I went out and shorted the starter relay, and voila, starter turned over.Off to the internet shops! Thanks to all.

[the mole]

AHHHH, free at last, now we can finally jump start our bikes from the car with the engine running without fear of damaging anything---I feel as though the weight of the world has been lifted from my shoulders.

Do I detect a note of sarcasm oj?
I can only agree with sledge on this issue. Every car, truck, bike, boat I've seen/worked on that has a 12volt system runs at a voltage of around 13.5-14.5 volts when the alternator/generator/regulator is in good shape. So, jumping your GS with a car that is running will have no detrimental effect on your electrical system if the donor vehicle's regulator is good.
Problems may arise, and might have in the OP's case, if you try to crank a reluctant engine for too long. With the standard GS battery this will likely result in a flat battery before too much harm is done to other components. With a jump start from a running car, you will likely fry the starter with too much cranking. You should definately rest the starter for a minute after 5-10 seconds of cranking to let it cool. During that time you can try to figure out why its not starting. If it doesn't start in 5-10 secs there is something wrong, no point burning out your starter as well.

I would like to point out that IF the donor vehicle's system is providing too many volts, then more current will flow through the starter, causing excess heat and possible failure.
Assuming the resistance of the load (starter) is essentially constant, V=IR, so if V is increased and R is unchanged, then I must increase proportionally. With more current (I) now flowing, P=VI shows that P is increased by the square of the increase in voltage. Note that this is an approximation, as R will change somewhat with current and temperature.
Looking at sledge's example, I think a better approximation would be:

With a nominal 100watt load,
At 12 volts:
I=P/V so I= 100/12, I=8.3 Amps.
V=IR, R=V/I, so R=12/8.3, R=1.45 ohms

At 16 volts:
V=IR, I=V/R so I=16/1.45, I=11amps
P=VI so P=16*11=177 watts

So going from 12 volts to 16 volts, the power has increased by about 75%.

Doing the numbers for 14 volts, the result is that P rises by about 35%.
That is why, if you're going to excessively crank a reluctant engine by jumping, its probably better to not have the donor vehicle running, but it will not have an adverse effect on your electrical system, which is designed to operate at 14+ volts.

[Worm]

I love the explanation sledge! So many people are worried about a car electrical system "forcing" it's high current on the bike and frying everything. I've read it in all of these posts about electrical problems. Thanks for the DC Circuit lesson for those who haven't had one!

[ojstinson]

Me? sarcastic?, perish the thought.

Think about it, do you really think anyone is going to jump start their bike with their car engine running after this---I stand by my statement about not using a running car to start your bike.


I think you and Sledge had better arm wrestle over the increased voltage- more current issue;

         You.
"IF the donor vehicle's system is providing too many volts, then more current will flow through the starter, causing excess heat and possible failure".

       Sledge.
"You will find it states that in a DC circuit if power remains constant and voltage increases, current DECREASES, not as you claim increases".



I'm so confused!