Need a new coil, but......

DukesFin · Jul 6, 2007

Okay, here is the boat/issue I am having...

1974 OMC GM L6 250 cid motor. I've got electronic ignition and always have. The problem I am having is it seems the engine "boggs down" after running WOT for a couple of miles. I'll be doing 35 mph for a couple of miles, then she runs like I have an obstruction in the fuel line, bogging down, forcing me to slow to around 20mph, then 15 or so, then to 5. At this point, I anchor the boat, turn it off and sit for a while, letting her cool down. Once cooled off, I crank her back up, and she runs great... for a couple of miles until the "bogging down" issue begins again.

By "feeling" and "hearing" it when I'm driving, I have realized it is an ignition issue instead of fuel delivery problems that I am having.

I know coils can overheat and cause similar issues, and I know that condensers can go bad and cause these issues. I don't have my boat up here in Atlanta with me, it's down in Florida so I can't run out to check if I've got a condensor or not. What I do know is that I've got Pertronix Electronic Ignition, a coil and a BALLAST RESISTOR. I do not have a "special" coil, just the stock MARINE coil and I do not have an ignition module "box" either...

So, my question is, can anyone tell me if I do have a condenser INSIDE my distributor cap? Should I replace the coil, ballast resistor and condensor (if I have one)?

Any help would be greatly appreciated!

Duke

bomar76 · Jul 6, 2007

Re: Need a new coil, but......

Not sure how your physic powers enabled you to deduce this is a coil (or non existant condenser) problem, but I would check and test the fuel delivery system via the hands on methods described elsewhere in this forum before I threw random ignition parts at it.

DukesFin · Jul 6, 2007

Re: Need a new coil, but......

New carb, cleaned tank, new fuel lines (fill, vent and feed), and a new tank of gasoline. Pump is working, etc, etc, etc...

Fuel was my first thought so I replaced everything involving the fuel system (it was all old except for my newer fuel pump - less than a year old)...

No psychic powers working here, just tried the obvious and what I knew needed to be done anyway (replacing all old parts), first!

So, back to an ignition problem? That is about all that is left on my drive train that is not new or freshly rebuilt...

I lean towards coil and condenser as I have a buddy who had the same exact symptoms and his issue was a bad (or going bad) condenser...

Sorry, I didn't elaborate more on the feeling and hearing while driving... I should have known the psychic comment would come! (warranted as it was)!

Haut Medoc · Jul 6, 2007

Re: Need a new coil, but......

Sounds like a fuel issue, not an ignition one......
I would try driving it until it does it, then switch to a 6 gallon portable tank immediately & see if you can get it to do it.....
6 gallons should be enough to see either way....
Will it quit or will you be able to idle all day long?
I know you draine dyour fuel tank, but I would pull the pickup & look at the screen as well as drain the tank from where the pick up was removed........

Don S · Jul 6, 2007

Re: Need a new coil, but......

It sure sounds like a fuel problem to me, you may have a lot of new parts in the fuel system, but I would sure do some testing BEFORE you put any more parts into it.
Try this. http://forums.iboats.com/showthread.php?t=167561

So, my question is, can anyone tell me if I do have a condenser INSIDE my distributor cap?

Take the cap off and LOOK!!!!! you may even have a bad cap or rotor, they do go bad also. Have you inspected them lately?
As far as a condenser, electronic ignitions don't use them.
I have also heard of coils doing this, but usually after one or two times they go out completely.

DukesFin · Jul 6, 2007

Re: Need a new coil, but......

I can idle all day long with no issues.

Pickup was clean when tank was cleaned and all fuel lines replaced.

My apologies for not stating this sooner... I know this gets on peoples nerves, but I was trying to avoid stuff I have already ruled out, though I'm open to re-visit those issues if need be...

This has been an ongoing issue on my boat since shortly after I bought it. At first, it would sputter a bit at higher RPMs, but the problem has gotten and continues to get worse. This past winter, is when I replaced all fuel related parts as they were old and needed replacing anyway. This did not solve the problem, nor did it make it any worse.

Again, the issue is getting worse, not better....

Sorry again for not stating this stuff sooner... My mind was in the right place, but not all of it when I first posted!

Bondo · Jul 6, 2007

Re: Need a new coil, but......

Ayuh,.............

Sounds like a Fuel Delivery Issue to Me too...........
And,.....
Anytime I've had a Coil Issue,.... It only lasted a short time after the 1st incident.......

A replacement Coil is Not that expensive if you want to Try it............

As Don mentions,...... What's the general Condition of the Rest of the Igntion system,..???

DukesFin · Jul 6, 2007

Re: Need a new coil, but......

I'll go over the fuel system again and double, then triple check everything from that side...

Problem is, the boat is still down in Florida and I'm back up here in Atlanta.

My wife and I took my mother in law down to Florida this past week and I didn't have permission to work on the boat while MIL was down there with us. Further inspection and repairs will have to wait a couple of weeks until I can get down there again.

In the mean time, I think I'll pick up a new coil, distributor cap and ballast resistor, since I do not know the age of those parts that are on my boat. I'll install them while I'm going through the fuel parts again!

Thanks for the help guys... sorry for leaving out so much on the subject!

Too many more repairs/maintenance, and my wife says I'll have to start posting in the OUTBOARD section!

Don S · Jul 6, 2007

Re: Need a new coil, but......

I'll go over the fuel system again and double, then triple check everything from that side...

Don't just look at things and replace things in the fuel system, you already looked at them, and you will see the same thing. Do the tests stated in the link I gave you earlier and see what they tell you.

The ballast resistor can fail in only one way........ OPEN, then it won't work at all and you will have a no run condition.

Too many more repairs/maintenance, and my wife says I'll have to start posting in the OUTBOARD section!

Have you ever counted all the posts in all the different outboard forums?????
What makes you think they wouldn't suffer from the same problem you now have?

Coors · Jul 6, 2007

Re: Need a new coil, but......

I think, that in the process of replacing all the fuel stuff; you knocked a bunch of crap loose.
And it will take several filter changes to clean it all out. Both filters, and maybe a carb bowl, at the end.

whywhyzed · Jul 6, 2007

Re: Need a new coil, but......

or you ran a fuel line somewhere it's getting hot and now it's vapour locking

xltier · Jul 6, 2007

Re: Need a new coil, but......

how about getting one of those spark checkers that go in the plug wire and flash a blue lite.`````````````you could put it in the coil wire and watch it blink as u run the boat.that would rule out ignition .if you have a helper you could fing a way to richen your fuel mixture when its acting up.be very careful,but maybe manually choking it.get down on your knees and hang on w2hile doing it.had one last week that one of the venturis would stop spraying gas half way down the lake.carb. fixed it.hth

Coors · Jul 6, 2007

Re: Need a new coil, but......

or get an outboard tank, and run out of there for a couple of minutes?

Don S · Jul 6, 2007

Re: Need a new coil, but......

Coors said:
or get an outboard tank, and run out of there for a couple of minutes?

Yea, you could do that, but if that cures the problem, you still have to do the test to find what the problem actually is. That or replace some more parts and call the old one old, even if they were ok.

Coors · Jul 6, 2007

Re: Need a new coil, but......

Don; nobody want's to perform your fuel test.
I link it to people, and they won't do it.
That test should be a sticky; I think all the younger guys have no clue how to use a vacuum gauge. Only us old farts do.
I think they still sell them...

Don S · Jul 6, 2007

Re: Need a new coil, but......

No, the problem is they don't want to do testing, or troubleshooting, they want someone to give them a quick and simple answer. Of course in real life, that ain't gonna' happen.

Coors · Jul 6, 2007

Re: Need a new coil, but......

That's why the pop in here?
You have the crystal ball.
It all makes sense now.
You are retired, and can Obi-Wan there fixes!

Don S · Jul 6, 2007

Re: Need a new coil, but......

Here is what 90% of the people are looking for.

KaGee · Jul 6, 2007

Re: Need a new coil, but......

Don S said:
Here is what 90% of the people are looking for.

Thanks Don... I'll need that when I remove my tilt motor tomorrow!

mkpj1 · Jul 6, 2007

Re: Need a new coil, but......

No condensor using Pertronix as Don S stated.

Pertronix box could be going bad. Check with Pertronix on how to test as you should be able to with a multimeter.

The hot fuel line sounds good. Or a bad pump reacting to the engine heat.
All vapor and no Gas.
You KNOW your pump is working? How did you test it? Put a T valve between the carb and the pump with a pressure gauge and run the boat. See if you get a drop when your boat acts up.

I have no idea what the pressure should be assuming it's a mechanical, shouldn't be more than 10 psi?
Could do the same at the coil with a multimeter.

Compression test? No gas in the oil?

Simple deduction Watson.

Need a new coil, but......

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