4.3 mercrusier crank no start

[al0311]

hi guys trying to open the boat for the season.
Charged the batteries and to start and it is just cranking. Checked and im getting fuel from the carb so i dont think its a fuel issue, for now... anyway, next I figured it might be an ingnition problem. So i pull a few spark plugs and i get no spark. Since i was able to run the boat a few months ago i find it strange that multiple spark plugs went bad. So i test power to the ignition coil. I have about 10.56 volts going to the postive of the coil, and .55 volts on the negative this is with key on.
Bad coil ? I tried to test the coil another way i connected it to a battery and ran some wires from the coil to a pulled spark plug and i got spark on the plug so that made me think its not a bad coil.
Im really not sure where to go from here. Shoud i test the distrubutor next ? If so how do i do that ?
Btw its a 1990 4.3 merc
of note before i closed it last year i had to replace the choke thermostat sensor on the side of the carb and i didnt get a chance to run it with it on. Could that be bad or the wrong part ? Any advice id apperciate.
Thanks

 

[alldodge]

about 10.56 volts going to the postive of the coil, and .55 volts on the negative this is with key on.
Bad coil ?

It's hardly never the coil

10.56V is pretty much a dead battery, your should have at least 12.5V after charging

It cranks over but how fast, is it kind of slow?
Should have a TB-IV ignition but I would work on the bat first

Now if you meant 12.56V then run thru this troubleshooting guide. This is TBV but is the same for IV

 

[al0311]

Thanks for the feedback. Is the red white wire inside the distributor? I only see one wire coming from the coil to the distributor. But then again I haven’t taken the distributor apart so it might be further down in it ?

 

[alldodge]

In the first post you said, it was a 1990 so it should have more then one wire, unless the ignition has been changed out

 

[al0311]

I’m almost postive there’s one black wire running to the distributor condenser. That’s under the cap. Do I remove that top cover part? I’ll have to look again in the am

 

[alldodge]

distributor condenser.

With one black wire then you have points and condenser. So I would start with replacing points and condenser

 

[al0311]

Question. I tested the ignition coil today on the negative post battery on key. And I was reading 1.56 volts ? Should that be reading anything ?

 

[Bondo]

Ayuh,.... That's not a coil test,.....

Have ya pulled the distributor cap yet,..??
What did ya see,..??

 

[al0311]

Yeah I pulled the distributor I have a condenser and points system weird right ? Anyway I also pulled the coil wire from the coil to distributor and grounded it to the riser. Weird thing is I had no spark cranking it. But when I turned the key on and off I had spark ?

 

[Bondo]

Ayuh,..... It's the Points, that fire the coil,......

 

[al0311]

Ahhhhh I think I’m following you. so you think the points are the culprit ?

 

[al0311]

I thought the condenser fires the coil ?

 

[alldodge]

Your points are not adjusted correctly. The points open and close for each cylinder to fire the coil. The points close, the condenser charges, and when the points open the discharge happens and fires the coil. With it only sparking when the key is turned, then the points are not closing and need to be adjusted correctly

 

[al0311]

Thanks so much!! I’ll give it a shot tommorow and report back

 

[Scott Danforth]

file your points, then set initially with feeler gauges, then final adjust with dwell meter.

this must be done every spring with points.

 

[al0311]

So I pulled the points apart and was looking at it and this is what I saw. Don’t think the fixed point should have a hole in it right ? Lol

 

[Maclin]

Some are vented like that from my automotive experiences.

 

[alldodge]

Need to get all the rust off the plate

 

[Bondo]

Ayuh,..... The hole is irrelevant, but the corrosion is enough to stop 'em from groundin' out the coil,....