OMC Ford 302 Prestolite ignition weak spark

[uncle dan]

So I have changed everything like the ignition switch that was not providing enough amperage at 12v to the alternator -- replaced voltage regulator -- now charging properly. New coil now and it runs but has weak spark!!!! The original coil didn't have a resistor in it nor was there a resistor in the lead.. It has to be the ignition module RIGHT. Before I buy a 3854077 module for big bucks I want to hear from someone smarter that me on this issue.
Uncle Dan

 

[Don S]

Re: OMC Ford 302 Prestolite ignition weak spark

Before you replace the module, go up and read the first thread in the ....ADULTS ONLY... sticky.

With the engine info you have given, an answers is completely impossible.

 

[a70eliminator]

Re: OMC Ford 302 Prestolite ignition weak spark

What about the secondary ignition? pnts condnsr wrs cap.

 

[Don S]

Re: OMC Ford 302 Prestolite ignition weak spark

What about the secondary ignition? pnts condnsr wrs cap.

Points type ignition systems don't have "modules", of any kind.

 

[a70eliminator]

Re: OMC Ford 302 Prestolite ignition weak spark

Well than crap I don't know what the heck, my OMC has prestolite distributor with points ignition, like you said all a guessing game.

 

[chiefalen]

Re: OMC Ford 302 Prestolite ignition weak spark

You didn't mention the plug wires ?

Want to try something very simple and free ?

At night or in a dark garage, run the motor, what do you see ?

Sparks flying all over ?

If yes you will know where the problem is.

One other thing and simple free also, the grounds good ?

The cables good and clean.

Follow the neg cable to the ground clean it good, take it off and get it shiny clean.

How about the connections on the starter clean ?

The juice first goes to the starter and than the coil ?

Check the connections and you will find the problem.

One more thing the cap good and clean inside ?

 

[uncle dan]

Re: OMC Ford 302 Prestolite ignition weak spark

The boat is a Four Winns 1995 with a OMC 302fl and a OMC outdrive. The distributor is breakerless from the factory. When I use a metal object to trip the pick-up I still get a weak spark.. I have checked the voltages at the module and the coil and they show 12v. I had a problem with the alternator overcharging due to low voltage being delivered to the regulator (due to a bad ignition switch) The alternator is charging properly now and I wonder if the high voltage that the alternator put out (since it detected low voltage at the regulator) cooked the distributor module... I like the idea of a BAD ground and will check it out. I get weak spark using the coil high tension lead to ground...

 

[Don S]

Re: OMC Ford 302 Prestolite ignition weak spark

New coil now and it runs but has weak spark!!!! The original coil didn't have a resistor in it nor was there a resistor in the lead..

You have the Prestolite BID system. You state you changed the coil. Did you put the proper coil in when you changed it? or add a resistor or something.

 

[uncle dan]

Re: OMC Ford 302 Prestolite ignition weak spark

The oem coil was not an internally resisted and I replaced it with a internal resisted one. There isn't a resistor in the line that comes from the ignition switch. The coil has a full 12v on the positive side and there is a full 12v going to the module in the distributor. When I put the oem coil back in I get the same results. I checked the gap between the rotor and the pickup and it is within specs. On a side note the company that made the ignition switch that was original equipment in this boat and many other brands was sued in a class action suit a I never knew a thing about it!!! Until I replaced the switch I had many electrical gremlins with this boat! Thanks for all the replies to my problem.
Uncle Dan

 

[Don S]

Re: OMC Ford 302 Prestolite ignition weak spark

The oem coil was not an internally resisted and I replaced it with a internal resisted one.

Soooooo, just to understand this, you replaced the OEM coil that didn't have an internal resistor built in, there is no external resistor or resistor wire, these resistors were all installed to prevent points from burning up really fast, and your distributor doesn't have points to begin with because it's an electronic ignition. Am I right so far?
So you now have weak spark since you replaced the OEM coil (without an internal resistor) with what you though should be there (one with an internal resistor), is that correct?
Personally, I have never installed a coil on a boat that I thought it should have, I usually just get the right part as suggested by the manufacturer. I really have no idea if it's an internally resisted coil or not. But they worked.
I do know that many years ago a customer replaced his points distributor on a Volvo with a new BID distributor like you have, but failed to remove the external resistor. It was hard starting, and didn't run well, (missed a lot). Once the external resistor was removed, it started and ran fine.

 

[chiefalen]

Re: OMC Ford 302 Prestolite ignition weak spark

No internal resister means a resister WIRE was there.

Looks like a regular wire.

Replace he wire, with a none resister wire.

One thing i didn't ask you do have a slav solenoid ? Connections good on that ?

Depends on your replys but i have hooked up a jumper to test the coil, to see if it good juice to the coil. But you must not leave it on. Only to test kapiche ?

 

[Don S]

Re: OMC Ford 302 Prestolite ignition weak spark

No internal resister means a resister WIRE was there.

No it doesn't! It may also mean a resistor wire or resister isn't used. Remember one other thing

HE DOES NOT HAVE A POINTS TYPE IGNITION

He has a Prestolite BID distributor.

No resistor wire, or resister​

Get the proper coil and it will probably work fine.

 

[chiefalen]

Re: OMC Ford 302 Prestolite ignition weak spark

Why people don't get the OEM parts i can't understand ?

The same exact one that was on the boat to begin with ?

This is not to chide or insult you sir; but another guy bought the wrong alternator had all kinds of trouble with it.

Don s is as always correct get the right coil and post the result.

 

[uncle dan]

Re: OMC Ford 302 Prestolite ignition weak spark

Ok since I never used a multimeter to check the old coil for a short (it produced a weak spark) I just replaced it with a internally resisted coil and it produced the same weak spark then it is possible that the old coil was bad and the new one with the resistor was the wrong one. The Four Winns wiring diagram shows a resistor in the line that feeds the coil and since I get a constant 12v from that lead I thought there should be either a inline resistor or a internal resistor and that is why I used the coil that I installed...... The boat is in a barn a few miles from my house but the oem coil is in my garage and I will get it and test it for a short.... when my regulator was bad my alternator was charging at full rate-- that is 18v and that could easily have cooked the oem coil and or the module. Thanks again. Brainstorming is almost as much fun as getting up to my elbows in grease or wires as is the case
Uncle Dan