1977 mercruiser 140

[powerstrokeplumber87]

My mercruiser 140 abruptly starting missing last year and I’m just now getting around to working on it. I can’t even get it to fire now. I’ve replaced the Coil, Cap and Rotor, and put 4 new plugs in it. It’s getting fuel and I have spark coming directly off the coil wire that goes to the center of the distributor cap if I pull it off the distributor I have spark. When connected I get zero spark or fire on any of my plugs I have pulled all 4 plugs and the result is the same on all 4. Any help would be greatly appreciated

 

[Bt Doctur]

bad rotor, cracked rotor, broken rotor

 

[Scott Danforth]

Its never the coil

You did service the points, correct

You did verify dwell and timing, correct

 

[powerstrokeplumber87]

I did not service points nor did I check timing I haven’t gotten that far yet. Was gonna ask if that is where I should start.

 

[Scott Danforth]

Yes, every year

File the points
Gap the points
Verify the dwell (32 degrees)
Set the timing
adjust idle speed

 

[Benny67]

Its never the coil

He's got spark at the coil..so the coil is good.

For the record, I've seen a few coils fail..so, no, " never the coil" isn't the case

 

[Benny67]

I did not service points nor did I check timing I haven’t gotten that far yet. Was gonna ask if that is where I should start.

Dollars to donuts you either pinched a wire when you installed the new cap or your points and/ or capacitor (condenser) are effed..

Maybe installing a pertronix ignition module might be a good choice?

 

[Scott Danforth]

He's got spark at the coil..so the coil is good.

For the record, I've seen a few coils fail..so, no, " never the coil" isn't the case

he replaced the coil before he verified spark

and yes, only about 3 out of a million changed coils are actually bad. so thats pretty close to never the coil. people change coils because its easy and they assume that is a proble without diagnostic testing. mostly because there is a youtube video showing someone how to change a coil. most of the time its a fuel related problem and people do not do enough diagnosis to understand that and they start throwing parts at it

just like our OP started throwing parts at the problem when the root cause was lack of annual service on the points. with proper maintenance, points get replaced every 20 years or so in a boat applications, however need an annual service to make sure they are operating properly.

 

[Grub54891]

Usually I just file the points in the spring, check timing/dwell and go boating all summer. This is my "beater" boat. Mercruiser 140 1984. Of course drive/engine service in the fall. The points are I don't know how old but preform just fine.

 

[powerstrokeplumber87]

Scott I doubt is fuel related due to the fact I disconnected the fuel line and it ejects fuel a good distance when cranking the engine and you can smell it in the carburetor after cranking. The motor with randomly fire up but it runs god awful like it’s running on 2 cylinders. And I changed the coil because it didn’t have any spark as the new one does. The inside of my distributor is all black like something exploded the old cap was destroyed and the rotor aswell. Tonight I plan on filing the points as suggested would installing a new condenser be wise. I have a set of points and new condenser I got with the boat

 

[Scott Danforth]

with "black like something exploded) it should just have been carbon arcing. however see if there is any wiggle movement of the shaft side to side. if so, you may need new distributor bushings (Napa has them for about $5)

 

[powerstrokeplumber87]

Update. I replaced the condenser bot fired right up at the bump of a key first try. Thank you everyone for help and suggestions it’s greatly appreciated

 

[Benny67]

and yes, only about 3 out of a million changed coils are actually bad. so thats pretty close to never the coil. .

Not for nothing but you seem to throw around your own beliefs as facts.

It might be wrong of me but I just can't read stuff like this in a help forum and NOT help myself to chime in to say that these beliefs of yours are just that, your beliefs.

I'm gonna start buying lotto tickets now, seeing I've come across 2 of your suspected bad coils in the past 35 years of repairing autos and boats. I must be lucky.

 

[Benny67]

And I changed the coil because it didn’t have any spark as the new one does.

WHOA....what's the odds of that?

Allegedly 3 in a million...