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tom
tom, Marine Mechanic
Category: Boat
Satisfied Customers: 117
Experience:  32 yrs exp. certified Johnson/Evinrude, Mercury outboards , also omc/cobra sterndrives
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I have an antique 1966 Chrysler 75 hp engine. There is no spark

Customer Question

I have an antique 1966 Chrysler 75 hp engine. There is no spark to the spark plugs. I have used a voltmeter to trace the breakdown and have not found a problem.

Is there way to check the distributor and the points?
Submitted: 6 years ago.
Category: Boat
Expert:  tom replied 6 years ago.
Hello I'm Tom and I'll be happy to help. you must first insure that you have a fully charged battery, many problems with a battery CD type ignition can be attributed to a weak battery or a faulty ground,(maintenance free batteries are not recommended ) , also, accidental reversal of the battery cables can damage the CD module and the rectifier. Connect a spark gap tester to the high tension lead coming from the ignition coil and set it to about 1/2". If it fires when you crank the engine over, there is a problem in the distributor cap, rotor button or spark plug wires.

Check voltage on the blue wire at cranking. It needs to be at least 9½ volts. if not, the problem is likely in the harness, key switch, or battery.Connect a " DC voltmeter to the white/black wire, while it's connected to the distributor, and rotate the engine. There should be some change in the meter reading. If it's high, and fails to move up and down, there is a problem inside the distributor. If the reading is low, disconnect the white/black wire from the distributor and with the key switch turned on, strike the white/black wire against an engine ground. The unit should fire each time. If it does, then the CD module is usually good and the points need checking. If the CD module fails to fire with this test, then the CD module is usually bad, check voltage on the gray wire going to the coil, with DVA meter, it should be 200 volts at cranking. If the voltage is right from the CD module, replace the coil. A coil that is shorted internally will give a low reading, if the reading is low, replace the coil. thanks-tom



Edited by tom on 6/23/2010 at 8:29 PM EST
Customer: replied 6 years ago.

I will test the answer this weekend. I am hopeful to diagnosis the problem.

I will send an email over the weekend.

Expert:  tom replied 6 years ago.

you can post back here to your question,--Tom

Customer: replied 6 years ago.

 

tests results below, unsure what they mean

I purchased a brand new battery.

 

 

Connect a spark gap tester to the high tension lead coming from the ignition coil and set it to about 1/2". If it fires when you crank the engine over, there is a problem in the distributor cap, rotor button or spark plug wires.

I assume you want the spark plug tester at the bottom of the coil going to the distributor.

That test resulted in no spark. GOOD or BAD?

 

Check voltage on the blue wire at cranking. It needs to be at least 9½ volts. if not, the problem is likely in the harness, key switch, or battery.

Tested good, brand new battery

 

Connect a " DC voltmeter to the white/black wire, while it's connected to the distributor, and rotate the engine. There should be some change in the meter reading. If it's high, and fails to move up and down, there is a problem inside the distributor.

12 volt reading, did not go up or down. Nest Step?

 

If the reading is low, disconnect the white/black wire from the distributor and with the key switch turned on, strike the white/black wire against an engine ground. The unit should fire each time. If it does, then the CD module is usually good and the points need checking. Reading was high, but checked CD module just in case. Did you want a spark when against a engine ground or distributor turning?

 

check voltage on the gray wire going to the coil, with DVA meter, it should be 200 volts at cranking. No gray wire going to coil(blue and shite), gray wire going to aternattor/stator. Are you referring to different test? What does DVA meter stand for?

 

Expert:  tom replied 6 years ago.
Hi, yes the spark checker should be on the wire from the coil to the distributor, if no spark, and if the voltage on the blue wire is 9 1/2 volts or better then, connect a DC voltmeter to the white/black wire (while it is connected to the distributor) and rotate the engine by hand, There should be some fluctuation in the meter reading. If the reading is high, and fails to move up and down, there is definitely a problem inside the distributor. If the reading is low, disconnect the white/black wire from the distributor and with the key switch turned on, tap the white/black wire against an engine ground. The unit should fire each time. If it does, then the CD module is usually good and the points require checking. If the CD module fails to fire with this test, then the CD module is usually bad.

A DVA meter is a peak reading voltmeter, it is different from a standard meter, the voltage you are checking is of very short duration and the average multi-meter can't read peak A/C voltage because they drop off too fast, the DVA type has a means to capture that voltage and feed it to the meter at a rate that displays it at its peak, a DVA reading will always be higher than a standard multi-meter, there are many type of DVA meters like the Stevens CD77 but they are expensive and for this one repair it would not be practical to buy one. The tests above should tell you if the CD module is good or not, however I must say that with engines of this age you may have more than one faulty part, thanks for your question-------Tom

tom and 3 other Boat Specialists are ready to help you
Customer: replied 6 years ago.

Is there a way to check th points under the flywheel without taking off the flywheel?

 

There should be some fluctuation in the meter reading. If the reading is high, and fails to move up and down, there is definitely a problem inside the distributor.

Any idea on what to check on the distributor?

 

check voltage on the gray wire going to the coil, with DVA meter, it should be 200 volts at cranking. No gray wire going to coil(blue and shite), gray wire going to alternator/stator. Are you referring to the coil of the alternator/(stator)?

Customer: replied 6 years ago.

I think we are getting close to an answer for the orginal question of no spark to the spark plugs.

 

I will gladly pay a bonus if we can use the scientific method to figure out the issue.

 

If I hook one lead of the ohmmeter to the terminal on the distributor and the other to the ground and rotate the flywheel, the meter goes from good connection to as none(making and losing connection with the points, which is good).

 

But if I turn the key to send power and rotate the flywheel and check voltage, the meter does not go from good to none. Any thoughts on these new developments?Surprised

 

 

Expert:  tom replied 6 years ago.
Hello again, I'm sorry, I meant to correct myself on the blue/white wire (long day), the alternator won't have any bearing on our problem, yes, the ohm meter is a good idea, it sounds like the points are making contact, I have been looking for some more information on distributor tests, I will get back to you tomorrow thanks---------tom
Expert:  tom replied 6 years ago.

Hello, it sounds like voltage is not getting past the module in the distributor, and unfortunately the only parts that are available in the distributor are the points and condensers, I spoke with Bryan at http://www.fairwindsmarina.com/chryslerpage.htm on the phone(NNN) NNN-NNNN and he said many of the ignition components are no longer available, however the tune up kits are (points,cond.) at this point I would take a look in the distributor, a visual inspection can sometimes reveal the problem. Bryan said you can give them a call if you wish and they will try to help you with the parts, some used parts are available, but used parts can be a gamble. thank you -Tom

Customer: replied 6 years ago.

 

thanks, XXXXX XXXXX able to purchase points and a condensor.

Some life is coming back to the boat. Boat does not start, but am getting some turnover and backfiring. I used some starting fluid to help start the boat, maybe causing the backfires. Any thoughts about the backfiring?

Expert:  tom replied 6 years ago.
Hello again, glad to hear you've got spark, the back fire could be caused by a couple of things, timing is the first thing that comes to mind that these engines were most sensitive to, the other things that will need attention are the carburetors and fuel delivery system ( lines, fuel pump, etc..) I would suggest that you contact either www.fairwindsmarina.com or www.maxrules.com to acquire the factory service manual if they still exist, the reason is the timing can be tricky and if not done correctly the module in the distributor can damaged. The after market books are fair but I prefer OEM manuals. The carburetors are pretty simple as far as carbs go, the main thing I do suggest is to replace the kits ( gaskets, needle valves, seats, floats) because the older material they are made of has no resistance to ethanol, and will begin to cause problems in themselves. The kits for the carbs should also still be available, thanks again--------Tom

Edited by tom on 7/3/2010 at 10:37 PM EST

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