5 VOLTS AT COIL NO SPARK

[400451501]

I HAVE A 79 SEARAY I/O WITH A 260 MERC. I ONLY HAVE 5 VOLTS TO MY COIL. I TESTED THE WIRES COMING OUT OF THE IGNITION 12 VOLTS. I TESTED THE WIRE ON THE SLAVE SOLENOID AND I HAVE 5 VOLTS. I REPLACED THE SLAVE SOLENOID AND ONLY HAVE 5 VOLTS. CAN SOMEONE HELP POINT ME IN THE CORRECT DIRECTION. THANKS

 

[DHPMARINE]

Re: 5 VOLTS AT COIL NO SPARK

I think you've lost at least me.Is the ignition 12 volts at the ignition switch? The 5 volts seems to be at the coil.Is this with the switch on and the points open.Do you have points ?<br /><br />Why does the slave solenoid get involved ?<br /><br />What voltage do you have at the coil when cranking the motor ?<br /><br />DHP

 

[400451501]

Re: 5 VOLTS AT COIL NO SPARK

i have 12 volts at the ignition. i have 12 volt at he ignition with the key on. i only have 5 volts at the coil with the switch on and the points open or closed.

 

[Boomyal]

Re: 5 VOLTS AT COIL NO SPARK

First of all the voltage to the coil is reduced by an inline ballast resistor to keep from burning up the points. Second, when you hit the starter the solenoid sends a full twelve volts to the coil until the key is released.<br /><br />So I recommend you do a voltage test at the plus side of the coil while you are cranking it. <br /><br />Beyond all that it sounds like your ballasted voltage may be too low. If I'm not mistaken it should be in the 7-9 volt range when the starter is not cranking. Someone else can verify or correct me.

 

[Dunaruna]

Re: 5 VOLTS AT COIL NO SPARK

No need to correct you, boom. You've got it in one.<br /><br />With the key in the 'start' position, the ballast resistor is bypassed and full battery voltage is supplied to the coil. Once the key is released into the 'on' position, the circuit runs through the ballast resistor which in turn supplies 7 - 9 volts to the coil.<br /><br />Searay, where exactly in the ignition circuit did you find 12 volts and what position was the key in?<br /><br />Aldo

 

[Don S]

Re: 5 VOLTS AT COIL NO SPARK

i only have 5 volts at the coil with the switch on and the points open or closed.

Then your points are dead, replace them, along with the condenser.<br />Then set the points with a dwell meter and check the timing afterwards with a timing light.<br />Point gap (Dwell)affects timing.<br /><br />You probably need a complete tuneup.

 

[Boomyal]

Re: 5 VOLTS AT COIL NO SPARK

Originally posted by Don S:<br />

i only have 5 volts at the coil with the switch on and the points open or closed.

Then your points are dead, replace them, along with the condenser.<br />Then set the points with a dwell meter and check the timing afterwards with a timing light.<br />Point gap (Dwell)affects timing.<br /><br />You probably need a complete tuneup.

Not to argue Don but why would 'dead' points, open or closed, affect the supply voltage at the coil?

 

[Don S]

Re: 5 VOLTS AT COIL NO SPARK

If the points had good contact, you wouldn't see any voltage at all on the minus side of the coil.

 

[Boomyal]

Re: 5 VOLTS AT COIL NO SPARK

Originally posted by Don S:<br /> If the points had good contact, you wouldn't see any voltage at all on the minus side of the coil.

Gotcha! Thanks. I did notice he did not say what side of the coil he took the reading from. I just assumed he would have taken it from the positive side.

 

[waterone1@aol.com]

Re: 5 VOLTS AT COIL NO SPARK

This one has me confused. I re-read the post and do not find any remark about the negative side of the coil. By the way, if he did take a voltage reading on the negative side of the coil (referenced to engine ground)and the points were open, there would be voltage there. 79SeaRAy,since you brought up things like the slave solenoid could you start at the begining please ? Does the engine crank over propperly ? If cranking nice, but not starting, did you use a spark tester on the coil output wire to verify there was no spark, or did you just pull one of the plug wires ? With the ignition on and your meter grounded to engine block and the meter positive probe on the coil positive terminal, what voltage do you get ? With someone turning the key to "start" what voltage do you get there ?

 

[rodbolt]

Re: 5 VOLTS AT COIL NO SPARK

it would not matter<br /> with the points closed you should really see no voltage between either post and ground, you may get a small bit thats being dropped by the coil but it will be insignificant. once the points(switch) is closed there is a complete circuit to ground. that means one end is at about the same potential as the other. points open and key on you should see about 12V. the ballast wire wont start resticting current without current flow. the current causes heat witch steps up the resistance. so back to the problem. at 5 volts with the points closed means the contacts on the points have incredibly high resistence. voltage is just potential, does not care much about resistance. current flow on the other hand does care. think of your points as a light switch. you may have 12v when the switch is open but when closed(under a load)no volts. if you have voltage acrossed the switch with the switch closed the switch has excessive resistance. high resistance means reduced current flow, reduced current flow means the primary coil winding magnetic field strentgh is to low to induce a voltage in the secondary windings which leads to no sparks. can also lead to much cursing and tossing of wrenches. a DVM can and will be your best friend,but only if you know what its telling you. think of it this way, your ground lead is connected at the distributor, your looking for a potential difference, wont matter which side of the closed points you set the positive lead on, the potential difference is the same. now go to the -term on the coil. if the wire from the points to the coil is good the potential is the same as at the dist body. now go to the + side of the coil. your now measuering the potential difference of the resistance of the primary windings of the coil. usually its not much resistance so there is not much voltage. open the points and it changes dramatically. a shorted or partially shorted( low resistaance) condenser can create some of the same results. remember the condenser is a large capacitor, it will block DC and pass AC. the rapid rise and fall of the voltage on the points acts like an AC signal. if you check it with a peak reading meter while running you will actually see about 150 volts or so. good luck and do a bit of studying on the primary and secondary coil operation and the muddy waters may clear a bit.

 

[400451501]

Re: 5 VOLTS AT COIL NO SPARK

Thanks to everyone and i am sorry I should of given you more detail. here we go.<br /><br />Lets start with the Ignition switch. I have 3 wires on the switch. Battery, i have 12 volts. Ignition, i have 12 volts with the key in the run position. Start, i have 12 volts in the Start position. <br /><br />Now to the coil.... With the Key in the run position. i ground my meter at the - side of the battery terminal and + lead to the + on the coil. It reads 5-6 volts. you were talking about a ballast resistor. if i have one i have no idea where it is located. <br /><br />When i put my meter on the + side of the coil and the - side of the battery and start the motor i am only getting 7-9 volts. <br /><br />The motor is cranking just fine. i have no spark. i checked for spark by pulling a wire. i also checked for spark by pulling the coil wire. i had nothing either place. <br /><br />I am not real good with a Points system. I figured when i didnt have 12 volts at the coil that was my problem. <br /><br />to give you some background for the year. in the spring i put a new coil on. the boat ran fine, brought it home. took it out again NO SPark. that is how it all started. then i lost my Starter fuse and replaced it. now i am back to my no spark problem.

 

[Don S]

Re: 5 VOLTS AT COIL NO SPARK

Now to the coil.... With the Key in the run position. i ground my meter at the - side of the battery terminal and + lead to the + on the coil. It reads 5-6 volts. you were talking about a ballast resistor. if i have one i have no idea where it is located.

That reading is basically useless information and is only the voltage drop across the coil, nothing else.<br /><br />

When i put my meter on the + side of the coil and the - side of the battery and start the motor i am only getting 7-9 volts.

7-9 is perfect.<br /><br />With the points open, if you check voltage on the - side of the coil (Red meter lead on coil, black meter lead on a good ground) you should see voltage. With the points closed, you won't see any voltage. If you do see voltage, then the points are not making good contact, and they need replaced.

 

[400451501]

Re: 5 VOLTS AT COIL NO SPARK

I will do that tonight when i get home.thanks