merc 470 eating up coils.

[Don S]

Re: merc 470 eating up coils.

The neutral safety switch only stops the starter from cranking the engine, has nothing to do with the engine starting or the ignition system in general.

The kill switch can stop the engine from starting, but will not damage a coil.

Little things like bad plug wires, or bad spark plugs can damage a coil.

 

[nola mike]

Re: merc 470 eating up coils.

I do have a multimeter but I couldn't get it started to check voltage. I ran it this last weekend and I got just over 14V at the alternator and less at the coil. I have a theory but I'm not too sold on it.....The whole no start thing happened a couple more times this weekend and all I did was jiggle the throttle and then it started. Could it be the neutral safety switch? This is where I'm not sure about my theory because I always thought that switch wouldn't let the engine crank and my engine did but just didn't start. Any ideas?

Depending on what kind I jiggling you're doing, you could have a sticking shift interrupt switch...

 

[Merc4ever]

Re: merc 470 eating up coils.

I know one thing from experience and that is that anything over 14 volts for a long time will destroy your battery.

 

[Eric 3.7LX Alpha 1]

Re: merc 470 eating up coils.

I do have a multimeter but I couldn't get it started to check voltage. I ran it this last weekend and I got just over 14V at the alternator and less at the coil. I have a theory but I'm not too sold on it.....The whole no start thing happened a couple more times this weekend and all I did was jiggle the throttle and then it started. Could it be the neutral safety switch? This is where I'm not sure about my theory because I always thought that switch wouldn't let the engine crank and my engine did but just didn't start. Any ideas?

That is exactly why you need a multi meter, when you can't start it. If you know what wires are suppose to have power on them (with the key switched to run and also start) you can check to see they actually do.

There is a test procedure for the coil. So you know if it's good or bad. All done with the engine not running...

You disconnect the wires off it, Set the multimeter to OHMs and check resistance. Check with both test leads (from the meter) on the primary.... (+) and (-) terminals on the coil , has to be within spec.

also test the secondary.... test leads on (+) of the coil and also the high tension lead (where the spark plug wire goes) that also has a range. If either are not within range the coil is NG. No guess work.

The spec for the coil is in the manual under engine specs.

 

[Eric 3.7LX Alpha 1]

Re: merc 470 eating up coils.

Sounds like you could use a manual:

Service manual# 3
http://boatinfo.no/lib/mercruiser/manuals/mercruiser3.html

see the attached page from the manual above:

 

[ferrall]

Re: merc 470 eating up coils.

Thanks for the info and for the manual!!