Still getting 12v to Coil after replacing resistor wire

[tu1aher1]

Hello all!

​First off, Thank you all for all the help you guys have helped me in the past. Now here is my problem:

I have a 85 Mercruiser 140 3.0 stern drive. I was having problems with the old points and condenser and the coil getting really hot, almost unable to tuch it. Through some research I found out that after engine start the most voltage I should be seeing would be 9 volts at the positive side of the coil. My engine has the resistor wire so I ordered one from mercruiser and replaced it according to the provided instruction, by the way was a lot of work. I also converted the points over to electronic system, The engine runs good now but I still have 11.8-12v after engine start and the coil get pretty hot after a few min of running. I'm afraid its going to break down on me in the middle of the lake one day.

Also it has a new starter and I re-did all the ground points from ignition to the starter to coil. What am I missing that is still pushing 12v to coil after start up? I know it gets 12 during ignition then should switch over to the lower voltage going through the resistor wire after start up. What could be pushing this 12v to coil? Thanks for all the help.

​I forgot to mention that it had this high voltage both before and still after replacing the starter.

Adam

 

[alldodge]

I'm seeing two issues,
1) previous coil was getting hot so you replaced the resistor wire.
2) changed to electronic ignition and still using resistor wire

When changing over to electronic ignition the resistor wire is no longer used. Also the coil should be changed to either one without a lablel or one that specifies it has an internal resistor (do not use one stating "use with external resistor")

Which electronic system did you use?

 

[tu1aher1]

Thanks for the reply. I purchased and installed the Electronic Conversion Kit - 18-5297 - Sierra. Here on iboats.com. Here is what the description stated:

• Replaces point & condensers for true solid state ignition
• Uses standard coil, cap and rotor
• Easy to install, one-piece, 2-wire hook-up
• Accurate to within 1/4 degree timing accuracy 0 to 6000 RPM range
• Can be used with Flame Thrower 18-5466 & 18-5469

I assumed that since it says it can be used with standard coil, cap and rotor, I didn't have to change anything.

​A quick note. I used to have a coil that had internal resistance but it would still over heat and cut out after a while. Although it also had the old resistor wire in the system as well.​

Right now I am using a coil with out internal resistance, per engine manual.

 

[alldodge]

It's basically a Petronix system, and the link below is troubleshooting guide. Note the one listing the amount of amps being drawn. You cannot exceed 8 amps, may need to add yet another resistor or the resistor wire with coil and internal resistor. The petronix have been problem childs

http://www.pertronix.com/support/tips/

 

[tu1aher1]

Thanks AllDodge, I'll go home and check my current usage and if needed I'll get a ballast resistor or a coil with an internal resistor. Do you know where I could get the ballast resistor?

 

[alldodge]

I got to thinking about what you said previous, that you had points and the coil was getting hot. A coil will draw more current if the condenser is starting to short out, the tachometer is drawing more or the coil. The system is pretty simple.

You change to petronix ignition which basically is an electronic switch, which replaces the points. It won't be the first time that a new module was the issue, but since you still have the same problem, I'm going to lean toward the tach or the negative side of the coil wire causing an issue.

Do you have a tach and if so have you tried disconnecting it?

 

[tango13]

Correct me if I am wrong, but wont the Pertronix unit not work if there is a resistor wire? The coil (if externally resisted) needs the resistor wire.. But, wouldnt that resister wire provide too much resistance for the electronic ignition to not work properly? Unless the pertronix has its own 12v source

 

[alldodge]

Yes and No, the above link in post 4 list it can be used with the resistor wire to reduce current. The resistor will reduce voltage but since the petronix module does not draw the same current to run as points and condenser, the voltage drop is less.

I really don't like the petronix because they either work great or they give ya problems and there is no clear rime or reason as to why. But this is just my opinion

 

[tango13]

Yes and No, the above link in post 4 list it can be used with the resistor wire to reduce current. The resistor will reduce voltage but since the petronix module does not draw the same current to run as points and condenser, the voltage drop is less.

I really don't like the petronix because they either work great or they give ya problems and there is no clear rime or reason as to why. But this is just my opinion

Thanks for pointing that out AllDodge, I see exactly what your saying. I have been trying to research whether or not I can use the ignitor kit on my own engine with the existing externally resisted coil/resister wire and I think you just helped me figure that out

 

[bruceb58]

I think you don't understand why you are measuring so much voltage. While the engine is running. The voltage drop through the resistor wire only happens while the points or the electronic switch is closed. When it is open, you will see full battery voltage. The reason you see full battery voltage is because there is no current flowing through the resistor wire.

When the engine is running, the alternator output is around 14V. You are seeing 11.8V which is the average voltage including the voltage while the points/switch is closed and when it is open.

For example, let's say your dwell was 45?. That means your points are open and closed half of the time. If the open voltage was 14V and the closed Voltage was 9V, your approximate average voltage would be around 11.5V.

 

[tu1aher1]

To AllDodge: Yes I do have a tach wire connected to that negative side of the coil. I have not tried removing the tact cable and I will try that and see if the coil temp is lower.

​To bruce58: You bring up a interesting point. Maybe I'm worrying about nothing. As I stated earlier the Sierra Petronix clone has been working fine, well let me define fine. I installed it and took the boat out a couple of days ago for the first time with the new module. I was out for about an hour and a half going different places then stopping short durations at a time. I did keep an eye on the coil and it seemed very hot. I could touch it but not for very long.

​I guess I need to ask the question: Is it normal for coils to get that hot? It's not searing hot to where it would instantly burn you but its pretty darn hot.

I'm going with a couple of buddies this weekend for an over night fishing trip on the lake and I don't want to become the butt of long lasting joke, if you know what I mean.

 

[bruceb58]

Yes, coils get hot.

 

[thumpar]

I put in a pertronix in my last boat and really liked it. My dad has one in his 66 mustang. When I did mine I switched the coil to an internal ballast coil and ran a new non resistance wire. Sometimes the pertronix don't like not having full voltage.

 

[Fishermark]

Just to add my 2 pennies... I too have used Pertronix brand kits several times and I have never had any problems with any of them. I HAVE had problems with the "Hot Spark" brand, which looks a lot like the Pertronix kit. I ended up putting in a Delco EST distibutor kit. You can shop around and find pretty good deals on a complete kit. I know you already have this one... but for future reference, for about the same money you can get a complete electronic distributor and wires.

 

[tu1aher1]

I have an update on this thread. I took the boat out this weekend for the over night fishing trip I mentioned before with a couple of my buddies. Every thing went fine the whole night. We fished in several different spots stopping then going to other places. A while after the sun came up the boat started having the same old problem it had in the past. We were putting along about 25mph then all the sudden the engine would die. I put it in neutral with a little throttle and the boat would start up again just fine but as soon as I came back to idle and put it in gear, give it gas it would die. I noticed there is a slight hesitation right when I push the throttle forward then under normal operation the engine would get past the hesitation and rev up. But now when this problem started to happen when I pushed forward on the throttle in gear the engine would encounter the hesitation but not make it over or "catch up" and just die. At first when it died going at cruse speed I could put it in idle and start it up again, put it in gear and get it passed the hesitation and then it would take off like doing a wheelie because ot the throttle being so forward but eventually it would die agin at cruse. I would start the engine again in idle and put it in gear and a load on the propeller it would die. It would run great when in neutral and I could rev it up as high as I wanted it to go.
​
I am completely baffled. the two problems:

1. Why did it eventually start dying at cruise speed?

2. Why is it dying at rest when I put a load on the propeller?

Are the problems connected? It seems like they are.

I verified the carb is getting gas. I tried to make some adjustments to the idle you name it, nothing. It is either electrical or carb as much as I can tell. I thought maybe the coil is getting too hot as I described above so I took it out and cooled in down in a lake water being carefull only to put only the bottom in the water. I had it nice and cool but still not fix.

I very much appreciate any insight that any one could give me for this very elusive problem.

Thank you guys.

 

[alldodge]

Did you remove the tach wire and see if the issue went away?

 

[stonyloam]

OK, pardon me if I missed it in the thread, but you MUST run 12V to the Petronix module, so you would run the resistance wire to the coil, but you would attach the red Petronix wire to a switched 12V source. Most use the purple wire from the ignition to the electric choke. If the module is not getting a full 12V it could be at least part of the problem.

 

[tu1aher1]

Hi everyone.

Alldodge, unfortunatly when I was on the lake having the problem I did remove the tach wire but it did not solve the problem, even with a cooled down coil. I just left it off and its still off.

​stonyloam, Well I'm basically getting 12v right now the way it is. I'm getting 11.8. But the engine would run fine as long as it's in idle. I could rev it up to red line if I wanted. It's only when I would put a load on it that it would die as I stated above. But I could run it to the purple auto choke. I never thought about that.

I would like to pose something else though. I have been reading that this problem is a common issue when the carberator has a bad accereator pump. If I were to do a carb rebuild would this fix the accelerator pump? I had it rebuilt last year and it had this problem back then too right after the rebuild. Any advice on this would be great. Thanks for all the help everyone.

This is how I feel :frusty:

 

[alldodge]

The accelerator pump is used to give the motor extra gas has the throttle is moved forward. If it doesn't get the extra gas it bogs down and can die but also can come on up if the throttle is given slow enough. Your dying at full planning speed, to me your running out of gas, either by a dirty carb or bad fuel pump. If it was the ignition module it wouldn't fire right back up.

Yes rebuilding the carb and replacing the accelerator pump will help if not fix the issue, IF the carb is rebuilt correctly and IF this isn't the only issue. Other issues include IMO, restriction in the fuel supply lines, filters, connections and such

I suggest checking your full pump pressure, it should be between 4 to 7 psi.

Also being your fuel pump is mounted to the block, check your oil level and see if its higher then normal. If it is, your full pump is leaking into the block.

 

[tu1aher1]

I have an update. I got a buddy of mine to come over yesterday so I could check the accelerator pump while he moved the throttle forward. I had him go from idle to forward in gear several times. Most of the times I just saw a few drops or dribbles of gas squirt into the carb. A couple of times there was nothing at all. One time it actually worked and I saw what looked like a shower of gas and the motor reved up pretty good. But nearly every time it was just a few drops or dribbles even when pushing forward pretty quickly. It would appear this is my problem. But why it died while at cruse speed I don't know.

​I think your right Alldodge. I believe there is a gas issue. I checked the oil like you said and it is at the correct level. I also checked the fuel filters, one in the pump and the one in the carb and both are clean. I did not check the fuel vent but I will. I did do some work on it last year and took a kink out of the line so I'm pretty sure it is ok but I can check it again. One little thing I forgot to mention. It may mean nothing at all but theses problems seem to happen when I'm at half empty tank of gas. Maybe its just always a coincidence but its always at this point when it does this.

My buddy know a lot about cars and he tells me it would be great of I could get away from the Rochester carb because they are known to be a pain in the neck back in the day with automobiles. He says they are constantly going out of adjustment at least with cars. He asked me if it was possible to put a Edlebrock on it instead?

Is there a Edlelbrock carb that would fit this Mercruiser? Of should I just rebuild the carb I have and change out the accelerator pump?

Thanks for any help.