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#11
posted to rec.boats
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Mercruiser Still Won't Start
I hear ya, Rob, but I don't think I stated things clearly. I meant to say
that I pulled the coil wire and held it near a ground. I ALSO looked for spark at the spark plug wire. I did NOT do both tests at the same time, although my statement makes it look like I did! I realize that there will be no spark at the plug wires if the coil wire is disconnected! I will check for 12 volts. I would have done so tonight, but my multimeter had a dead battery. Would I hold the probes to the pos and neg on the coil, or am I better off using another ground point? Back to the ballast resistor, I know what a ballast resistor from an old Dodge looks like, and I know what it does, but I cannot find one in the wiring diagram or on the boat. by pulling the coil wire and holding it near a ground, and by putting a spare spark plug into a plug wire. That is spark at the secondary side of the coil. You will get no spark at any plug wire with the coil wire pulled. Trust me... there is no spark. You really need to check that you have 12 volts at the coil while cranking, 9-10 volts in the "run" position. You will get no spark ever if you don't get this 12 volts cranking first, and have the points set to open to the specified gap twice every engine revolution. Rob |
#12
posted to rec.boats
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Mercruiser Still Won't Start
Thanks r_d,
I will follow your directions tomorrow night and report back. -Tim "r_d" wrote in message . com... "TSC" wrote in message ... I have the Siloc book. I went through the troubleshooting, and I have no spark anywhere. Curiously, the wiring diagrams in the book do not show an external ballast resistor. I have following the wires from the coil and I cannot locate one either. The original coil (which I replaced) says the only use it with an external resistor. I made sure the new coil was for use with an external resistor. Any clues as to where the resisitor would be? Would a faulty resistor allow it to crank, but show no spark? Note that I checked for spark at the points, by pulling the coil wire and holding it near a ground, and by putting a spare spark plug into a plug wire. Trust me... there is no spark. Ok let me ask you this... Key on do you see 12v on the positive (+) terminal of the coil with the key on? If NO then hooking up a wire with gator clips from the positive (+) battery terminal to the positive (+) side of the coil. See if it will start if so pull the clip off if it dies then you have a problem with the external resistor. In this case just ignore it, go get a internal resistor coil and run a wire directly from the ignition switch to the coil. Don't use the external resistor coil on 12 volts it will overheat. You can in the future use this new 12volt wire to run the electronic pickup that you will eventually install in place of the points...... I suspect this is not your problem as it will not start even when the starter is running. If YES there is power to coil with key on then I would unhook everything from the negative (-) terminal of the coil except for the points (should be a single wire running from points/condenser to coil). See if it starts and runs. If so tach is dead or short in shift interrupt system. The way the coil works is such... the coil charges when positive power is on and the coil is grounding though the points. When the lobe in the distributor gets to the proper position it opens the points breaking the ground to the coil and the power stops flowing in the secondary circuit in the coil. When this happens it creates a magnetic pulse in the coil that is picked up by the primary circuit and is send out of the coil as a high voltage "jolt" that is then sent to the plugs. If the ground circuit is always grounded no spark or if the circuit does not close (no ground) no spark. I bet this is where your problem is in the system. During cranking the starting system will feed a full 12volts to the coil then when the starter is off it feeds ~10volts to the coil through the resistor circuit (voltage will depend on the resistor but should be between 7-10volts). From what I have read in your posts I bet you have a ground issue. I went though something similar last year with my OMC. Let us know how you make out. good luck, mark |
#13
posted to rec.boats
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Mercruiser Still Won't Start
You really need to check that you have 12 volts at the coil while
cranking, 9-10 volts in the "run" position. You will get no spark ever if you don't get this 12 volts cranking first, and have the points set to open to the specified gap twice every engine revolution. Rob The fellow really needs to pay attention to your statements and begin systematic troubleshooting of the problem. Jim. |
#14
posted to rec.boats
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Mercruiser Still Won't Start
TSC wrote:
I hear ya, Rob, but I don't think I stated things clearly. I meant to say that I pulled the coil wire and held it near a ground. I ALSO looked for spark at the spark plug wire. I did NOT do both tests at the same time, although my statement makes it look like I did! I realize that there will be no spark at the plug wires if the coil wire is disconnected! I will check for 12 volts. I would have done so tonight, but my multimeter had a dead battery. Would I hold the probes to the pos and neg on the coil, or am I better off using another ground point? Back to the ballast resistor, I know what a ballast resistor from an old Dodge looks like, and I know what it does, but I cannot find one in the wiring diagram or on the boat. You are SOL w/o checking coil voltage, (+) to ground, not the switched (-) of the coil. You can use a 12 volt test probe or even a 1156 or 904 12v bulb to confirm there is power to the coil if your meter is DOA. There really is no sense in checking for spark distribution or generation until you get your ignition primary side confirmed working. I still don't get the part about checking the spark at the points... Rob |
#15
posted to rec.boats
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Mercruiser Still Won't Start
TSC wrote:
I hear ya, Rob, but I don't think I stated things clearly... .... Back to the ballast resistor, I know what a ballast resistor from an old Dodge looks like, and I know what it does, but I cannot find one in the wiring diagram or on the boat... It could be inside the harness, or it could be a section of resistance wire, or a ceramic block type between the terminal block(solenoid area) & the coil. Rob |
#16
posted to rec.boats
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Mercruiser Still Won't Start
"Danlw" wrote in message . .. "TSC" wrote in message ... Also, check the ground from the battery to the engine. He said it "cranks and cranks forever" - Hehe, can't do that with a bad battery to engine block connection. Have him check the "interupter switch" on the shifter cable. |
#17
posted to rec.boats
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Mercruiser Still Won't Start
It is not a matter of not paying attention. There are two objectives here.
The parts that I am removing and replacing are not a complete waste of time or money. We are talking about 20 year old ignition components that, even if they work, I am much more comfortable replacing for the price that they cost. So, despite how it appears, this is not a "replace everything and hope it works" approach. As I checked each of replaced parts I saw things that I did not like. Such as lots of carbon on the contacts inside the distributor cap, cracks in the plug wires, etc etc. These are parts that have the potential to leave you stranded out on the water and warranted replacement. It is not so much that I really expected any individual part to miraculously solve my problem. When I read back through this thread, I can completely understand why you guys are frustrated that I have not checked for 12 volts yet. Trust me, on the way tonight I will buy a GOOD multimeter instead of the piece of junk I use for pinball machine repair and I will follow your advice to the letter. I really do appreciate the advice. Thanks Tim "Jim" wrote in message link.net... You really need to check that you have 12 volts at the coil while cranking, 9-10 volts in the "run" position. You will get no spark ever if you don't get this 12 volts cranking first, and have the points set to open to the specified gap twice every engine revolution. Rob The fellow really needs to pay attention to your statements and begin systematic troubleshooting of the problem. Jim. |
#18
posted to rec.boats
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Mercruiser Still Won't Start
"TSC" wrote in message ... It is not a matter of not paying attention. There are two objectives here. The parts that I am removing and replacing are not a complete waste of time or money. We are talking about 20 year old ignition components that, even if they work, I am much more comfortable replacing for the price that they cost. So, despite how it appears, this is not a "replace everything and hope it works" approach. As I checked each of replaced parts I saw things that I did not like. Such as lots of carbon on the contacts inside the distributor cap, cracks in the plug wires, etc etc. These are parts that have the potential to leave you stranded out on the water and warranted replacement. It is not so much that I really expected any individual part to miraculously solve my problem. When I read back through this thread, I can completely understand why you guys are frustrated that I have not checked for 12 volts yet. Trust me, on the way tonight I will buy a GOOD multimeter instead of the piece of junk I use for pinball machine repair and I will follow your advice to the letter. I really do appreciate the advice. Thanks Tim "Jim" wrote in message link.net... You really need to check that you have 12 volts at the coil while cranking, 9-10 volts in the "run" position. You will get no spark ever if you don't get this 12 volts cranking first, and have the points set to open to the specified gap twice every engine revolution. Rob The fellow really needs to pay attention to your statements and begin systematic troubleshooting of the problem. Jim. Get an automotive multimeter that includes a dwell meter. Mercruisers use a resistive wire instead of a ballast resistor. If it is bad,you will find out in the course of troubleshooting. There is no need to rip your wire loom apart to find it. Jim |
#19
posted to rec.boats
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Mercruiser Still Won't Start
I do NOT see 12 volts on the positive side of the coil with the key on. This
is using a volt meter. I tested the volt meter at the battery and got the full 12 volts. Testing at the coil gives me nothing. Hooking up a wire with gator clips to the positive side of the battery to the positive side of the coil produces no change. Keeps turning over nice and strong, but no firing whatsoever. By the way, I *did* remove the tach wire while conducting all tests. I changed back to my original coil and performed the tests again. No change. I am going to have to wait for daylight to continue this saga. Ok let me ask you this... Key on do you see 12v on the positive (+) terminal of the coil with the key on? If NO then hooking up a wire with gator clips from the positive (+) battery terminal to the positive (+) side of the coil. See if it will start if so pull the clip off if it dies then you have a problem with the external resistor. In this case just ignore it, go get a internal resistor coil and run a wire directly from the ignition switch to the coil. Don't use the external resistor coil on 12 volts it will overheat. You can in the future use this new 12volt wire to run the electronic pickup that you will eventually install in place of the points...... I suspect this is not your problem as it will not start even when the starter is running. If YES there is power to coil with key on then I would unhook everything from the negative (-) terminal of the coil except for the points (should be a single wire running from points/condenser to coil). See if it starts and runs. If so tach is dead or short in shift interrupt system. The way the coil works is such... the coil charges when positive power is on and the coil is grounding though the points. When the lobe in the distributor gets to the proper position it opens the points breaking the ground to the coil and the power stops flowing in the secondary circuit in the coil. When this happens it creates a magnetic pulse in the coil that is picked up by the primary circuit and is send out of the coil as a high voltage "jolt" that is then sent to the plugs. If the ground circuit is always grounded no spark or if the circuit does not close (no ground) no spark. I bet this is where your problem is in the system. During cranking the starting system will feed a full 12volts to the coil then when the starter is off it feeds ~10volts to the coil through the resistor circuit (voltage will depend on the resistor but should be between 7-10volts). From what I have read in your posts I bet you have a ground issue. I went though something similar last year with my OMC. Let us know how you make out. good luck, mark |
#20
posted to rec.boats
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Mercruiser Still Won't Start
TSC wrote:
I do NOT see 12 volts on the positive side of the coil with the key on. This is using a volt meter. Digital or analog? I tested the volt meter at the battery and got the full 12 volts. Testing at the coil gives me nothing. The coil (+) and... What did you use for a ground(-)? Hooking up a wire with gator clips to the positive side of the battery to the positive side of the coil produces no change. Do you mean that you still do not have 12 volts at the coil to ground? What are you using for a ground on this test? There always has to be a reference to ground or we cannot help you figure this out. Keeps turning over nice and strong, but no firing whatsoever. You will get no spark ever if you don't get this 12 volts at the coil to ground cranking first, and have the points set to open to the specified gap twice every engine revolution. How did you set the points gap? By the way, I *did* remove the tach wire while conducting all tests. You removed it from what? It should be one of two connections at the (-) post on the coil. It won't make a lick of difference, though, if you still do not have 12 volts at the coil(+) to ground(not coil"-") while cranking. I changed back to my original coil and performed the tests again. No change. It won't make any difference which coil you use to get the 12 volts coil (+) to ground. I am going to have to wait for daylight to continue this saga. Let us know! Rob |
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