115 Mariner

[Cadwelder]

Is there a "most common" problem with the ignition system on this model (1987 Mariner 115, serial # 0B153107) does not have a distrubutor. IE switchbox, stator, coils, etc.

 

[CharlieB]

Re: 115 Mariner

1) Rectifier fails, causing strange EMF within stator which can have a negative effect on spark. Disconnect yellow stator wires and retest spark, if all is well then replace rectifier.

2) Poor ground on switchbox can toast a switchbox.

3) Dying rectifier and/or switchbox can overload stator and shorten stator life.

CDIElectronics.com build very high quality replacement parts, far more cost effective than OEM. And they have a very detailed Ignition Troubleshooting Guide avalable for FREE download.

 

[Cadwelder]

Re: 115 Mariner

Thanks, I've checked the ohm readings as per Selco manual and they check okay, coils, stater, trigger and switchbox, but I'm sure they would since the problem is intermittent. I first thougth it was fuel delivery but have eliminated all possible fuel problems. It still runs low speed fine but after a few minutes at WOT it starts cutting in and out, in and out as if half the cylinders quit firing and then start back again. From what I understand the switchbox's control three cylinders each. I'm leaning toward replacing the switchboxes and give it a try. Does this sound like a likely suspect or would you look elsewhere?

 

[CharlieB]

Re: 115 Mariner

Always remember there is NO RETURN on electrical parts, simply replacing parts is the most expensive method of attempting to repair a problem.

Diagnosing an intermittent problem takes attention to details.

A 'Tiny Tach' or even a timing light can help determine if the ignition is a problem, checking for a difference in RPM on each cyl or using the timing light to see if a cyl is firing irregularly can help identify an ignition problem.

Testing with a DVA meter or a DVA adaptor with your volt/ohms meter can show a reduced voltage from a stator, trigger, or a switchbox. It is awkward, but these test need to be done when the condition occurs to be certain of a correct diagnosis which will save you from spending money on un-necessary parts.

 

[Cadwelder]

Re: 115 Mariner

CharlieB, I checked the stator leads (red to blue) (red/white to blue/white). The Seloc manual gives the ohm values at 5.4 - 6.2. With the engine cold it checks within spec on both leads. After the engine ran for a while and started cutting in and out the (red to blue) value changed to 4.1 and the (red/white to blue/white) went to 5.3. I can see that are not within specs, so I'm guessing a bad stator or are the reading not far enough off to cause a problem?

Thanks,
Dave

 

[CharlieB]

Re: 115 Mariner

Conductivity of metals will vary with a rise in temperature. Those number didn't change that far off, AND they BOTH changed. Generally a problem in a stator is with one OR the other sets of windings, rarely both at the same time.

Ohm's readings can be misleading and the DVA has become pretty much an industry standard method of reliable testing. You can build your own DVA Adaptor for your volt meter quite cheaply, search these forums for the parts list and directions to build a DVA Adaptor.

Test the stator, trigger, and switch box output to the coils following the directions well spelled out in the FREE Ignition Troubleshooting Guide found at CDIElectronics.com

Their guide and your dva tests will very accurately diagnose which ignition parts is at fault, saving you much $$$$ by not buying expensive NON-returnable electrical parts.

 

[Cadwelder]

Re: 115 Mariner

Went to CDI website and went through the entire test process. I most definetly have a bad stator. Would you just replace the bad stator only? I'm thinking since the engine is 23 years old and it's only around $600.00 to replace all the ignition parts, it may be a good idea to just replace all of it.

Thanks for the great advice.

 

[Dave1027]

Re: 115 Mariner

I could see replacing the trigger while you have the flywheel off but replacing the rest is only a waste of money IMO.

 

[Cadwelder]

Re: 115 Mariner

Thanks Dave, I'll do just that, and you have a good point, other than the trigger and stator the rest of the componets are a breeze to get to later on.

 

[Cadwelder]

Re: 115 Mariner

All ignition checks out ok, problem is still there. I've suspected fuel all along but could find no problems there. It has new fuel pump clean carbs, new fuel filters, checked pick up in tank and tank vent. It seems to happen when tank reaches half full, what could the problem possibly be?

To refresh memory 1987 115 Mariner, runs a while thens bogs down, will run low speed all day long, when it Boggs down the primer bulb collapses as if there is a restriction but I can't find one anywhere. The fuel line goes straight to the tank, no other filters, autoblend, etc.

 

[CharlieB]

Re: 115 Mariner

When a fuel primer bulb collapses there is a vacuum on the fuel line, proving there is a restriction in the line somewhere between the bulb and the opening of the dip tube in the tank.

You may have a foreign object adrift in the tank that gets sucked against the dip tube, debris sucked up into the dip tube, a sticking check valve at the tank fitting, an inner tear in a fuel line from the tank. A crack in the dip tube will allow air to be sucked into the system once fuel level exposes the crack, but that would not flatten the primer.

You will have to inspect each piece of the fuel system to find the problem.

 

[Cadwelder]

Re: 115 Mariner

Thanks for reply, I've rechecked the pickup tube and just nothing there, wide open. The fuel line is new 3/8" marine approved line. The tank vent is wide open. I removed the tank this morning and emptied it completely, cleaned throughly and reinstalled. Went to the lake to give her a try and same problem is there. I even tried another primer bulb (new geniune Mercury) but it does the same thing. I agree there HAS to be a restriction to collaspe the bulb but where?? I even thought the fuel line is too small, but I've owned the boat since new and it's the same size line that been running for years on it, and a 3/8" primer bulb is the largest they make. I'm truly at a lost. Are there any other "tricks of the trade" to try?

I"ve thought about buying a johnny tank and taking with me to see if connecting it solves the problem, what are your thoughts there?

I can't think of anything on the powerhead itself that would cause this, the fuel pump is new and we know the fuel pump is pumping or the primer wouldn't collaspe, correct?

 

[redjmp]

Re: 115 Mariner

The pickup tube inside your tank usually has a little filter on the end which get get clogged. For sure a collapsed bulb can only mean a restriction between the bulb and the tank. Disassemble and check each piece of fuel line. E10 gas swells certain rubber compounds and breaks down fuel lines...

 

[Cadwelder]

Re: 115 Mariner

I am using the Ethanol Blend gasoline, it's about all you can find around here. Do you think I should find a station with straight gasoline? You are correct about the screen on the pick up tube, but it's clean and wide open. The fuel line is a rubber approved marine line. Do you think I should use the slick, gray Sierra fuel line instead of the black rubber line? I'm down to trying ANYTHING at this point.

 

[arsenalpsu]

Re: 115 Mariner

(forgetting about the fuel bulb right now, how flat is it?)

Did you check the spark plugs?? I had the exact same problem this summer on my 84 115hp and did all the tests, even with a DVA and nothing showed up bad. I decided to replace my Champ spark plugs with better quality NGK ones and tested the champs while i was pulling them out. AND one of the 6 had a resistance of .45, they should all be close to 0. (wish I would have started first with the plugs!!) Check yours, resistance from end to end should be almost nothing. Even if it "looks" fine there could be an internal problem causing intermittent spark.

 

[Cadwelder]

Re: 115 Mariner

Plugs are new NGK, less than 20 hours on them, but I'll certainly give them a test. Thanks.

 

[arsenalpsu]

Re: 115 Mariner

my champs were brand spanking new too, just replace them after i did a rebuild. If that isn't it then i would definitely buy one of those 6 gallon tanks from Walleyworld and take her for a spin- if she still does it than at least you've eliminated one possible problem. You'll find it eventually don't worry!

 

[Cadwelder]

Re: 115 Mariner

Very true, I learned a long time ago, just because somthing is NEW does not mean it's good.

 

[j_martin]

Re: 115 Mariner

(forgetting about the fuel bulb right now, how flat is it?)

Err, argh, if the fuel primer bulb is going flat (not just a little soft) it's not getting fuel. That means it's not getting fuel. That means somethings is wrong with the fuel line or tank. So why the heck are you suggesting spark problems?

 

[Cadwelder]

Re: 115 Mariner

It is collasped completly, (when the bogging down problem occurs) once you throttle back and let her idle a bit it pops back out. I've tried three different primer bulbs also but all do the same thing.