motor just up and quit.

[herefish101]

I was out fishing on saturday, my 1979 chrysler 75hp started right up, purred like a kitten. I took off across the lake and after about a mile or so, the motor just up and died, and would not re-fire. The plugs are dry, it has spark, and the float bowls on the carbs are full. So i should go after the carbs, right? I'm confused, to me it seems like I have all the ingrediants to fire in the hole. If any one can point me in a direction that maybe i'm overlooking, that would be very very helpful. Thanks.

[marine_man]

So it doesn't run at all right now? No cough or sputter? Seems odd that it would be a carb issue if it was running just fine and died on it's own and is completely dead now if it has all the components you mention. Perhaps a compression test is in order?

marine_man

[BoxMN]

Stator? I assume that motor has one. Our '87 merc 90 had a stator go bad once, it is just like a lightbulb, they either work or don't and no real reason to go. Something to check anyway, though I am not sure how to check it.

[kdawg]

Stator? I assume that motor has one. Our '87 merc 90 had a stator go bad once, it is just like a lightbulb, they either work or don't and no real reason to go. Something to check anyway, though I am not sure how to check it.

I'd agree - sounds more electrical in nature. Even a loose wire. I'd check from the motor to the battery and see what you can find (in addition to the stator). Good luck.

[53orbigger]

We had the same thing with a 30hp Johnson, just quit while running across the lake. We went through the fuel system then the electrical system replacing parts that we thought it might be to no avail. Finally did a compression test and found that it had a blown head gasket. You might want to start there, if we had, it would have saved us a couple hundred dollars. Good Luck.

[CAMAN]

If he has spark, it wouldn't be the stator.

Definitely do a compression test first.

[marine_man]

If he has spark, it wouldn't be the stator.

Definitely do a compression test first.

Unless it's a heat related thing... how soon after it stopped working did you check for spark?

marine_man

[CAMAN]

Yes, but I'm assuming he also tried to start it after he checked for spark, which it should have fired up if he had it and there were no other problems with the motor.

[herefish101]

new update

When the motor died and did not refire, i checked for spark, at this point it parked, and for fuel as far as the fuel filter, and i had fuel, it just wouldent start. Thank god for trolling motors.

Now i'v been working on it in my driveway, and there is no longer any spark. this motor has a CDI box which fires a coil, which goes to a preamp inside a ditributer. The plug wires test good, the distributer cap has no sighns of cross fire. The iffy part is the coil. The positive post of the coil is where the CDI box connects to the coil, when i put the volt meter on this post and crank the motor i get nothing, there should be like 200 volts pulsing at this point.

So now the million dollar question, is it the coil, or the CDI box? As these are both expensive parts, both of which i just replaced at the end of last year. I'm going to give myself a concussion beating my head against the motor.

P.S. I have 110psi on all three cylinders?

[walleyemaniac]

I'd put my .02 on the CDI box, had an old yamaha dirt bike that had one go bad. If it didn't want to run it wouldn't go back 5 minutes later it might start. No rhyme or reason why just worked when it wanted to.

Wouldn't think it was the coil once they go bad they're just bad.

[boatfixer]

The iffy part is the coil. The positive post of the coil is where the CDI box connects to the coil, when i put the volt meter on this post and crank the motor i get nothing, there should be like 200 volts pulsing at this point.

If there is no voltage to the coil then I wouldnt think the coil is the problem. Unfortunately there is no test for the CDI box. You need to test everything around it and if everything tests fine, then replace the CDI

[upnorth]

Kill switch bad?

[boatfixer]

Kill switch bad?

Yes it can definitly be the kill switch. Good point

[delcecchi]

I wouldn't replace the CDI until I had verified that power and ground were getting to it.

How is the CDI triggered? Magnet and a pickup of some kind? Is there any way to see if the pickup is good?

[herefish101]

I wouldn't replace the CDI until I had verified that power and ground were getting to it.

How is the CDI triggered? Magnet and a pickup of some kind? Is there any way to see if the pickup is good?

It's triggered by the preamp inside the distributer. Could the preamp be bad? I'v never know'n anyone who ever had to replace one. Ill try to find a a test for it

As for the kill switch, The voltmeter says it's workin properly, same with the neutral safty switch, As well as the overheat shutdown.

I'm rollin the dice, and going with the coil first

Any more help would be great, keep the ideas coming, thanks to all.

[boatfixer]

Chrysler

CHRYSLER TROUBLESHOOTING

Point Type Ignitions with Amplifiers (Power packs)

(Preamps are electronic replacements for points)

A large proportion of the problems with the battery CD units are caused by low battery voltage or bad ground connections. Low voltage symptoms are weak fire or erratic firing of cylinders. Maintenance free batteries are NOT recommended for this application.

WARNING!! Battery cable reversal will cause severe damage to the CD module and rectifier.

NOTE: The Chrysler CD modules are similar to the OMC CD modules with the exception of wire colors. The chart below will assist you as a general guideline:

Red

Blue

Gray

White

White/Black stripe

Black +12V from battery (RF Noise Filter)

+12V from key switch

+ Terminal of ignition coil

OEM Tachometer signal

Points or Preamp Module

- Engine ground

NO FIRE ON ANY CYLINDER:

1.Clean all battery connections and engine grounds.

2.Make sure the CD module is grounded. Units using rubber shock mounts require a ground wire fastened from the pack to the engine block.

3.Connect a spark gap tester to the high tension lead coming from the ignition coil and set it to approximately 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.

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

5.Connect a DC voltmeter to the white/black wire (while it is connected to the distributor) and rotate the engine. 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 rom the distributor and with the key switch turned on, strike the white/black wire against engine ground. The unit should fire each time. If it does, then the CD module is usually good and the points (or Preamp) require checking. If the CD module fails to fire with this test, then the CD module is usually bad.

6.Check DVA voltage on the gray wire going to the coil, it should be approximately 200 volts at cranking. If the voltage is right, replace the coil with another coil and retest or use a load resister if another coil is not available. A coil that is shorted internally will give a low reading. In this case replace the coil and retry.

After repairing the engine, check the battery voltage at approximately 3500 RPM, The MAXIMUM allowable voltage reading is 16 volts and the minimum is 12V. Running below l2V or over 16 volts will damage the ignition. Check for loose connections or a bad battery.

Magnapower II Systems

1.Disconnect the white and blue kill wires from the CD Module and retest. If the engine starts and inns, the key-switch or kill circuit is bad.

2.Connect a DC voltmeter from the kill wires to engine ground and turn the ignition switch on and off several times. At no time should you see battery voltage on a kill circuit.

3.Connect a spark gap tester to all cylinders and test with the spark plugs in and out. If the coils will not fire with the spark plugs in, check compression with the spark plugs removed from all cylinders. A blown head gasket on these engines can cause the coils not to fire with the spark plugs installed. This is caused by a hard to explain problem with the triggering circuit.

4.Crank the engine with the starter and then stop. Check the DVA voltage on terminals Ti and T4. You should read between 170 and 270 volts Positive on terminal Ti and between 170 and 270 volts Negative on terminal T4. (Remember that some DVA adapters are not polarized and will read the same regardless of the polarity). If there is a low reading on one of the terminals, disconnect the white/blue and green/white trigger wires, then retest. If the readings are now correct, one of the trigger modules is bad. A continued low reading may be caused by a bad capacitor. To test, use a couple of jumper wires and swap the green and white capacitor wires going to terminals Ti and T4. If the low reading remains on the same terminal, the CD is bad. If it moves when you move the capacitor wires, the capacitor is shorted.

5.Check to see if the ignition coils are wired correctly. The #1 coil on a two cylinder and the #1 & 2 cylinder on a four cylinder are wired as NEGATIVE GROUND. The #2 coil on a two cylinder and the #3 & 4 cylinder on a four cylinder are wired as POSITIVE GROUND.

[delcecchi]

A real test procedure. Way cheaper than what we used to call "easter egging". :-)

[auggie78]

Hopefully found someone nice enough to give you a tow back in

[herefish101]

thanks Boatfixer, i'll try all that stuff sunday.

[Big Buck Buster]

A real test procedure. Way cheaper than what we used to call "easter egging". :-)

Or "poke and hope" technology.

[herefish101]

Or "poke and hope" technology.

sounds about right, but i'm praying insted of hoping, if i cant get this fixed cheap my season is in terrible jeprody. wish me luck..........

[jeffreyd]

can you imagine using a test light on the 200 volt coil. that might just leave a mark.

[Big Buck Buster]

can you imagine using a test light on the 200 volt coil. that might just leave a mark.

I use test lights on coils all the time. Use it to test for dead cylinders with a piece of vacuum hose between the coil and the wire. Fire it up, and put the test light end on the vacuum hose to test spark and to check for rpm drop when spark grounded through the test light. Haven't taken a light out yet, and haven't gotten a nice jolt either.

BBB

[herefish101]

disconnect the white/black wire rom the distributor and with the key switch turned on, strike the white/black wire against engine ground. The unit should fire each time. If it does, then the CD module is usually good and the points (or Preamp) require checking.

O.k. i did this test and it fires every time, so by boatfixers test, the preamp is bad? Is this a good place to start? If you read this Boatfixer is there a test for the preamp? Your info is so much better than my seloc manual is not even funny. Thank you, to everyone who helped point me in this direction, hopefully i'm going down the right road.

[soldoncass]

The first thing you said was"it has spark, but the plugs are dry".....sounds to me like a fuel issue, maybe the fuel pump. It is just a diaphram that wears out and gets a hole in it.....no fuel to the plugs. At least my Evinrude did that once, and left me 3 miles from my truck.