Merc 3.0 has no spark

[DHPMARINE]

Re: Merc 3.0 has no spark

johnny,<br /><br />sometimes it is hard to tell who is joking and who is not.<br /><br />I was about to suggest that the operator was firmly seated in the operators seat before attempting to start,or operate.and wear proper footwear.<br /><br />DHP (joking) and not certified (at least as a tech).But certainly certifiable ready.

 

[muc]

Re: Merc 3.0 has no spark

Snowrider, sure does sound like a bad coil. Seems like you have done all the testing you can without buying a Mercruiser manual (always a good idea).<br />To you Mercruiser mechanics (certified or not) don’t be too quick to dismiss what those old boaters tell you. Now go grab Mercruiser Manual #1 go to section 3-E and look at the wiring diagrams for some old stuff. Ya it’s called a tilt limit and yup we did replace them. Hmm guess I’m not the only human that makes mistakes! MUC

 

[Don S]

Re: Merc 3.0 has no spark

You will probably change the coil and it still won't run. Look at the first reply to this thread. THE POINTS!!!!<br />Change the points, you can't tell by looking if they are good or bad, especially if you didn't even know where they were located.<br /><br />

I don't know a whole lot about the ignition system. Where exactly are the points. Also where is the safety kill switch

 

[r_snowrider]

Re: Merc 3.0 has no spark

Calm down there donny. I took the points to a certified mechanic and he told me they were fine. I also hooked up the spark plug to the the wire coming straight off the coil, and grounded it. Correct me if I am wrong, but if the coil were working it's built up charge would have briefly discharged when grounded. Also, you guys gave ox a pretty hard time, but apparently some boats were equiped with a tilt- limit cutoff. So I don't know who exactly to listen to.

 

[Don S]

Re: Merc 3.0 has no spark

 

[r_snowrider]

Re: Merc 3.0 has no spark

I didn't even know boats had a cutoff switch, I thought that you only found those on jet skis, my fault. But my boat does not have one, and if it does I can't find it. I am new to boating. I am new to working on boats. I don't often take my things to mechanics due to $ and I also like to learn stuff myself so I can know what the problem is in the future or when I am out on the lake. If it was something serious I would take it to the shop, because I respect a mechanics opinion very much.

 

[Bondo]

Re: Merc 3.0 has no spark

Boy, O Boy,..................<br />This thread belongs over at BoatingABC,.........<br />Tons of Misinformation,..........<br />And,..........<br />The Unknowledgeable Dumping on the Knowing.............<br /><br />Yes,... There is a "Trim limit switch"........<br />All it does is Stop the lifting of the Drive.......<br />It Doesn't stop the Engine in Any Way, Shape or Form.......... Totally Independent of the Engine..............<br />

oxbowman,.... I'm sure you old guys remember the 3 button trim panel? You know, the one that is marked UP, UP/OUT AND IN. It had a trim limit switch, some were above the bell housing up in the gimbal housing area. You would push the up/out button to trim and the limit switch would keep you from going out past the gimbal support guides. Now, when you wanted to trailer, you would push the up botton and the up/out button at the same time to bring the drive to the full up position(trailer). Now, that is the position my boat is in when it will not start!<br /> <br />If this Is how Your boat works,........<br />You've got a Short in Both the Trim system,+ the Engine Electrical system.......<br />This is NOT the way it was Designed..................

I took the points to a certified mechanic and he told me they were fine.

As Don(Donny to You, I Guess) has Already stated,..... You Can't Tell by Looking at them........<br /><br />Well,.. Hey,......<br />If you want to be a "Change a Part,+ HOPE mechanic,............<br />Keep going the way you're going..............<br /><br />If you want to Learn How to Diagnose the issues that'll pop up,.......<br />Listen the the Knowing,... Instead of the Guessers........

 

[Haut Medoc]

Re: Merc 3.0 has no spark

Two of the most knowledgeable people in this forum have now answered your post, if you are wise you will heed their advice, and post #2 as well .....JK

 

[r_snowrider]

Re: Merc 3.0 has no spark

Replaced the coil and the boat started right up. Will be taking it to the lake tomorrow and I'll report back. Vice Admiral Bondo, I'm sure you know a lot more than myself. But what else could I have done to diagnose the problem? I was getting power to the coil (12v)but I wasn't getting enough power off the coil to jump large enough gap. I mean checking the points was a great suggestion, but without a working coil the points would not have worked anyway. If I can't tell by looking at them, than how am I gonna be able to test them without a working coil? I mean your contradicting yourself, if you can't tell by looking at the points, and they still don't work after re-gapping them, then isn't the next solution to replace them? Doesn't that make me a "hope mechanic"? Or should I troubleshoot further up the line and test the other components to see if perhaps they may be the culprit before I run out and buy new points? Cause the points aren't going to work without a working coil. So should I just buy both? Or should I replace the non-working part first. Then if I am still not getting a spark, then I could have bad points as well. It just seems like common sense. Give me your perspective.

 

[Haut Medoc]

Re: Merc 3.0 has no spark

Glad you replaced the coil and solved your problem, but do you now get spark with the drive up. ..JK

 

[r_snowrider]

Re: Merc 3.0 has no spark

Sorry fellas, although the coil worked, new points made it run a lot smoother. Thanks for your help.

 

[bamadave]

Re: Merc 3.0 has no spark

At least he found where the POINT's are thru all of this!

 

[bamadave]

Re: Merc 3.0 has no spark

At least he found where the POINT's are thru all of this!

 

[waterone1@aol.com]

Re: Merc 3.0 has no spark

Snowrider, I'm glad your boat is now running right, that is the purpose of this forum. There still seams to be some confusion about a few things though, and since others may read this in the future....time to straighten out some things. 1) The coil and the voltage it produces on it's output (secondary) is several thousand volts, that is the reason it is able to jump the spark gap. While the old electricians trick of only touching the hot lead may work with 120 volts, it is not a safe practice for 30,000 volts. Standing in a cramped boat engine room, it is possible for your knee or other body part to be within sparking distance of ground (even through jeans). 2) The coil does not "feed" the points, it is the other way around. The points make and break the minus 12Volt connection to the coil. The small spark on the points has very little to do with what spark you will get on the output (secondary) of the coil. 3) The coil is a transformer, not a capacitor. The coil produces a high voltage output because the magnetic field is rapidly expanding and colapsing because the primary (12 volt side) is turning on and off. The +12Volt side is on and the points are opening and closing the 12V ground. The engine must be turning over (points making and breaking the connection) for there to be spark. You cannot turn on the ignition, then try to arc the coil output to ground, the engine must be cranking to do that.

 

[Dunaruna]

Re: Merc 3.0 has no spark

Originally posted by waterone1:<br /> The engine must be turning over (points making and breaking the connection) for there to be spark.

Not 100% correct my watery friend <br /><br />With the ign on, a person can manually open and close the points - causing a coil tower spark.<br /><br />That person, I believe, is snowrider.<br /><br />Aldo

 

[r_snowrider]

Re: Merc 3.0 has no spark

It is much more dangerous for someone to test a 120v wall outlet than a 20,000v current going through an engine. That is simply because the current is so much higher in the wall outlet. Current is the killer.

 

[waterone1@aol.com]

Re: Merc 3.0 has no spark

Sometimes, I just want to turn off my computer and say the he11 with it. If you think it is a safe practice to grab the output of an ignition coil.....be my guest. For anyone that has been shocked by a good healthy spark and thinks that having your vision go blank,your muscles spasm and being light headed for a few moments isn't dangerous.....you are an idiot.

 

[Haut Medoc]

Re: Merc 3.0 has no spark

Amperage is the killer! I must agree with waterone 1, while the shock from an auto engine probably won't kill you, under the right circumstances it could. Obviously, you have never been on the business end of the wrong wire or you would be thinking differently. By the way, did changing the coil fix your 'No spark with drive up' condition?

 

[boull]

Re: Merc 3.0 has no spark

I can't believe I'm jumping into this but what the hell....<br /><br />There may not be much current, but the damage you can do to your body when you react to 30KV can be pretty substancial. Ripping your arm away and getting it caugt on something can cause a severe cut, banging your head in an enclosed area not good, etc etc

 

[r_snowrider]

Re: Merc 3.0 has no spark

You called me an idiot and now I must go on the defensive.<br /><br />"The coil and the voltage it produces on it's output (secondary) is several thousand volts, that is the reason it is able to jump the spark gap. While the old electricians trick of only touching the hot lead may work with 120 volts, it is not a safe practice for 30,000 volts"<br /> -Waterone1<br /><br />Ok buddy, I'm not gonna argue that touching the power coming of a coil is safe, although I did it. Your calling me an idiot? You just tried to tell me that touching a 120v wall outlet is safe. Ask someone who knows anything about electricity, which is more likely to cause harm. Have you ever touched the spark coming off an electric push-button lighter? There's about 20000v coming off that puppy, and your certainly not putting you life in danger. How about rubbing your feet on the carpet and touching a doorknob, we all know that the spark can arc just as far as the electricity off a spark plug. Although it is much more dangerous to touch a spark plug wire than get shocked from a household static charge, that still doesn't change your argument that you are safer putting your fingers in an outlet. On top of all that the current coming off a coil is only a split second flash, because the coil has to recharge. The electricity coming off a wall outlet is constant. Do me a favor and stick your finger in an outlet. And I'll contact the Darwin awards for you. Please call your local college, ask for the electronics professor and ask the question of which is safer. He'll hang up the phone laughing. I may not know a hell of a lot about boats, but you don't know jack about electricity.