No voltage at coil when trying to start...

[knehdn]

I have an'89 Raven with a Mercruiser 470. Won't start.
Checked voltage at coil terminals ... none.
- key on - no voltage
-start - no voltage
Checked coil pos. to battery neg. - 0.00vdc
- key on - 11.5vdc
- start - 10.4vdc
- no engine sputter = no spark?
Checked coil neg. to battery pos. - 12.42vdc.
Removed choke connector wires.
- key on 12.35vdc
Does this indicate a bad coil?
Am I missing to check something?
Please and thank you..
.

 

[bruceb58]

Some of your voltage measurements do not make sense. On one line you have voltage but the next line you say you do have voltage! Also, some are just not valid tests. For example, you don't need to measure voltage across the coil terminals themselves.

With the ignition on, measuring from the pos terminal of the coil to ground, you should have either full battery voltage or around 7V or so depending if your points are open or not. With points closed, you have current running trough the resistor wire which is why it would be lower.

If you pull a plug wire and test the spark to ground, do you see a spark?

When was the last time you changed your points and what is the dwell measured with a dwell meter?

 

[Bt Doctur]

remove the wires from the neg side of the coil and install a jumper wire.
supply 12v to the + side of the coil with another jumper from the battery
"scratch" the jumper on the neg side to a ground. coil should make sparks

 

[knehdn]

Tested the coil with a multi-meter. 1.4ohms between the positive terminal and the negative terminal. Seems OK.
But when I tested between the coil terminal and either the positive or negative terminals, no reading on the 2000 ohm scale,
no reading on the 20K ohm scale. It only showed a reading on the 200K scale which was 118.6K ohms. That seems high as far as
what I've read lately. Guess I need a new coil.

 

[Bondo]

Guess I need a new coil.

Ayuh,.... Put the multimeter down for a few minutes,.....

With the key, On,.... Is there voltage at the coil's (+) terminal,..??

 

[knehdn]

I'll check in the morning. Thanks.

 

[stonyloam]

Nothing that you have done so far indicates a bad coil.

 

[knehdn]

Checked voltage at positive terminal of coil and ground ... key on ... 12.5 vdc.

 

[knehdn]

I did as Bt Doctur instructed .... I taped the coil output wire 1/8" from ground ... fed 12.5 vdc to positive coil terminal .... jumped negative coil terminal to ground ...
no spark from coil output to ground.
I'm doing something wrong. Right?
just no idea, other than a faulty coil, why there's no spark.... but Terry seems to think that the coil is OK.
I'm confused.
Oh yea ... it's an '89 - 3.7L 470 motor.
It started and ran great last year, even when I winterized it.

 

[Fishermark]

I did as Bt Doctur instructed .... I taped the coil output wire 1/8" from ground ... fed 12.5 vdc to positive coil terminal .... jumped negative coil terminal to ground ...
no spark from coil output to ground.
I'm doing something wrong. Right?

You don't simply jump the negative side to ground, you tap the negative to ground. You don't hold it there. Every time you tap it you should get a spark.

Oh yea ... it's an '89 - 3.7L 470 motor.
It started and ran great last year, even when I winterized it.

Best bet is simply that the points are glazed over from sitting. Very common. Either file the points or put new ones in.

 

[knehdn]

I did tap the jumper to ground ... no spark from coil output.
I cleaned the points. Still not starting once all was put back to normal.
I'll pick up a spark tester tomorrow and try that on Friday.
Tune-up including points etc. was completed last spring before initial launch.

I do appreciate the advice from everyone..

Will let you know how the spark tester fared on the weekend.

Thanks again.

 

[Bondo]

I did tap the jumper to ground ... no spark from coil output.
I cleaned the points. Still not starting once all was put back to normal.
I'll pick up a spark tester tomorrow and try that on Friday.
Tune-up including points etc. was completed last spring before initial launch.

Ayuh,...... Maybe ya need the coil,....

Points, are an Annual maintenance item,......

That's why everybody likes the electronic conversions,.... No Annual changin' the points,.....

 

[bruceb58]

I did tap the jumper to ground ... no spark from coil output.

Did you do this test with all the wires removed from the negative side of the coil except your jumper?

Was there 12V at the positive side of the coil referenced to the block ground when you did the test?

 

[stonyloam]

Yeah, NOW it sounds like you may have a bad coil. When you ground the coil you should get a spark every time you REMOVE the ground (when the points open). Does the ground wire spark against the ground? If not you may not have a good ground.

 

[bruceb58]

Yeah, NOW it sounds like you may have a bad coil. When you ground the coil you should get a spark every time you REMOVE the ground (when the points open). Does the ground wire spark against the ground? If not you may not have a good ground.

You won't get a spark if the coil is being grounded through closed points! That's why I asked if he removed existing wires off the coil.

 

[stonyloam]

Oops, missed that Bruce. Yes remove all but the ground jumper.

 

[knehdn]

Kinda figured it was the coil, mainly because of the 119,000 ohms of resistance between the positive terminal and the distributor feed. Called a local marine supply house. Told it was an old style oil filled coil. Said cost was about 80 bucks plus taxes and 2 to 3 weeks to get one ordered. Then called the local NAPA. Stock item, $49 plus taxes. Bought it. Put it in. A little throttle ... wham, kicked in right away .... ran like a dream. So much for the marine supply expert.
Then I noticed the trim cylinders were jamming. Fixed them too. Ready for the water on my next day off.

Thanks to all for all the feedback and help with the coil problem.