Is a ballast resistor ever used with a Breakerless ignition?

[KM7]

My 91 5.8 L Ford motor on my Four Winns came stock with the Prestolite Breakerless Inductive Distributor (BID) ignition.
I'm testing the coil to address some idle issues. I may replace the coil and want to be certain that I'm getting the right one.

The book says the stock coil is a OEM 3852217 or Sierra 18-5437. Some of the pictures of those coils do say "Use with external resistor". The coil on there now is a Diamond E-035. It also says right on it "Use with external resistor".

But I have seen a lot of discussion that an external resistor is only needed for a breakerpoint ignition and that if you were upgrading from a breakerpoint ignition to a breakerless ignition the ballast resistor was NOT to be used. The mechanic that used to work on the boat says he DID add the resistor. Was that wrong?

Is testing the primary and secondary resistance using a basic Ohm meter good enough or do I need to take it to someone with an analyzer?

I got 2 ohms on the primary if I wait till it stops changing (book says 1.43 - 1.58) On the secondary I get 7.2 Kohms (book says 7.5 - 8.7)

Thanks

 

[Scott Danforth]

yes, some electronic ignition system still use a ballast resistor

you are worried about nothing with your coil, as only 3 out of a million coils that are changed are actually bad.

so what is the issue you are having that erroneously makes you think its the coil

(hint, its probably fuel system related)

 

[KM7]

@ Scott I can't get the idle below 1000 without stalling when I shift. Above 1000 it does not stall but shifting is hard especially coming out of gear back to neutral. The ESA is working correctly and will kick in but it still does not want to come out of gear.

I have the OD shift cable adjusted correctly and the settings at the engine bracket all correct per the OMC manual as well.

Carb is rebuilt, Fuel/air may not be exact because I can't get the idle down where it belongs. I do start with the mixture screws at 7/8 out per the manual.

What do you suggest?

 

[KM7]

scott You said "Only 3 out of a million coils that are changed are actually bad" Why do you say that?

What is the best way to test a coil? If this coil is original and I follow the manual it fails.

 

[jimmbo]

Is the Tach accurate?, Is the Initial Timing set correctly?
You can adjust the Carb, even at a Higher Idle speed to see how the engine responds.

 

[Scott Danforth]

Fist go back to the ESA and use the factory manual to set it. I believe Lou C has a good write up. The OMC ESA system is a PITA to adjust properly

Coils either work, or they dont, there is the rare moment when coils start loosing their oil. However most people change coils because its easy and they mis-diagnosed the issue to begin with.

Your motor runs, so your coil is fine

 

[KM7]

jimmbo The tach is in a dwell-tachometer It's a bit old but I think is works fine. The tach on the boat has never been accurate. I could connect the dwell-tach to my 4Runner and see it the rpm matches. I have set the fuel/air with the idle as low as I could get it,

scott i have the ESA adjusted by the book. You could be right about the coil but I have a hard time getting the idle down below 1000. I suspected a weak spark. The coil may not be completely dead but could it have broken down a little and cause a weak spark?

I tried the coil tests by the book and both the primary and secondary resistance were low.

Is there another way to evaluate the spark?

I do have a tool that creates a gap simulating a spark plug at .035 in. It clamps on to a ground.

Can you tell a good spark by what it looks like?

 

[Lou C]

I’m thinking you have a carb problem in that the idle system is dirty to the point where it will not idle slow enough to work properly with the ESA. For an engine with an OMC ESA to idle and shift right with no stalling you need a smooth shift cable (less that 2.5 lbs drag) free moving and greased bell crank in the pivot housing, properly adjusted cables (both the transom shift cable and the remote cable) and the remote control itself must be in good with no lost motion.
So:
you need to get the carb clean enough that:
it will idle smooth at 600 rpm
it will momentarily idle without stalling at 450 rpm
thats how much the ESA lowers the idle to get it to drop out out of gear.
BTW the only maintenance I have done on my OMC shift system:
each season pull drive clean out pocket in the pivot housing pack with OMC triple guard grease. Grease all pivot points for shift linkage on engine bracket
at 27 years old the micro switches were worn out so I replaced them, and replaced the module with one from CDI electronics because the original quit working

your problem is likely tune up or carb related unrelated to the ESA unless it’s sticking on with it in gear that would be a very sticky transom shift cable.
Start with the carb...plugs...cap...rotor....plug wires...

 

[KM7]

Lou You could be right, I replaced all the fuel lines at the end of last season due to the rubber breaking down. Here is a picture of what got trapped in the carb intake filter.

I had the carb rebuilt after that and drained all the fuel and got rid of it. I even tilted the boat to get every last bit of old fuel/gunk out. Then I rebuild the the fuel pump myself. I cranked the motor over to pump clean fuel through the lines and into a bucket before I hooked everything up. Before I had done all this the carb did Not have a nice even spray down the throat but dribbled. After all this it does have a fine spray.

To be sure, I could take the filter out of the carb and look for any more deposits.

Then I could disassemble the carb again, look for and clean it out any crud.

I still think that the the ballast resistor that the mechanic installed was wrong. It drops the voltage to the coil at low idle. That could be contributing to my problem Everything I read from good sources says that you do not need a ballast resistor on a pointless, Prestolite ignition like mine. Do you agree?

I'll do some more tests on the coil and measure the voltage with it at idle and at a higher rpm. I would expect lower voltage from the resistor at lower rpm and that is not what I want. Maybe I will add spade connector to the wire so I can add and remove the resistor easily. And I suppose if I do change out the coil, I'll keep the old one on the boat just in case removing the resistor shortens the life of a new coil.

BTW the schematic does not show a ballast resistor.

What do you guys think?

 

[Lou C]

Ok 2 things:
i cant answer the question on the ballast resistor because I don’t have a wiring diagram for your year, mine does have a resistance wire but it’s a points ignition which usually had a ballast resistor when used in auto applications. See if you can at least find a factory wiring diagram or pick up a factory shop manual. I have one for my 88 and they are very good.
Second for the carbthat is a lot of crud and corrosion, I have gone thru my Quadrajet a few times and never saw that, your water separating filter should be catching that I’d think. Having said that the idle emulsion tubes in my Quadrajet were still dirty and I really blasted them out the last time I had it apart and it will idle at 550 rpm and if you trigger the ESA lever it will idle down to 450 rpm and will not stall. So can’t answer the first question w/o a diagram but for the carb I think it might still be dirty.

 

[Lou C]

If the schematic does not show the ballast it could still have a resistance wire; that is not necessarily shown on the schematic but should be mentioned on the ignition section of the shop manual if it is used.

 

[Lou C]

Just thought of this, you might try calling the tech guys at CDI electronics, they make ESA units for OMC engines and might be able to tell you if you need a resistance wire or ballast resistor or not. It ma depend on the resistance of the coil you are using..

 

[Scott Danforth]

scott iThe coil may not be completely dead but could it have broken down a little and cause a weak spark?

coils either work, or they dont.

you have a carb issue.

 

[KM7]

Lou attached are schematic for the boat and the schematic for just the ignition. Neither schematic discuss a ballast resistor, but that may not mean that one is not used. I know a 1990 with a breakerpoint ignition Does use a ballast resistor and that schematic does not show one either.

Yea - Lots of crud. I hope it was all cleaned out of the tank and lines before I put the carb back on but I may have to disassemble it again. You said you had crud in the Idle Emulsion tubes. Can you show me where that would be? Here is an exploded view.

scott you may be right. I'll check the carb

 

[Bt Doctur]

open the mixture screws more, open till it runs rich and stumbles, close it until the rpms pick up then open a 1/2 turn

 

[KM7]

@ Bt Doc Here are the plugs before I cleaned them. Do you still think I'm running too lean?

 

[KM7]

Update: After removing the ballast resistor from the system, replacing the distributor cap and filing the edge of the rotor. (I have a new rotor on order) It is running very well now. I did readjust to idle mixture. Now they are at 1 5/8 turns out.

The idle is now about 800 and that is in the driveway on the muffs. I expect it will be lower in the water.

So, going back to my initial question: Is a ballast resistor ever used on a breakerless ignition? I can't say never but mine seems to run great without it.

I took a video of the rpm surging a bit before I adjusted the idle mixture. Then I took another video after the adjustment. It is much smoother. I'll post a link to both videos.

 

[KM7]

Update: After removing the ballast resistor from the system, replacing the distributor cap and filing the edge of the rotor. (I have a new rotor on order) It is running very well now. I did readjust to idle mixture. Now they are at 1 5/8 turns out.

The idle is now about 800 and that is in the driveway on the muffs. I expect it will be lower in the water.

So, going back to my initial question: Is a ballast resistor ever used on a breakerless ignition? I can't say never but mine seems to run great without it.

I took a video of the rpm surging a bit before I adjusted the idle mixture. Then I took another video after the adjustment. It is much smoother. I'll post a link to both videos.

Before adjustment: https://youtu.be/IdEym0ynBIs

After adjustment:

 

[KM7]

Update: After removing the ballast resistor from the system, replacing the distributor cap and filing the edge of the rotor. (I have a new rotor on order) It is running very well now. I did readjust to idle mixture. Now they are at 1 5/8 turns out.

The idle is now about 800 and that is in the driveway on the muffs. I expect it will be lower in the water.

So, going back to my initial question: Is a ballast resistor ever used on a breakerless ignition? I can't say never but mine seems to run great without it.

I took a video of the rpm surging a bit before I adjusted the idle mixture. Then I took another video after the adjustment. It is much smoother. I'll post a link to both videos.

 

[KM7]

xxx