Engine running rough.... Here we go again !

[bigdog]

MAXUM,

Just to answer a few of your concerns and suggestions:

-Gas treated before winter storage
-Carb rebuild a year ago, all new parts including 'float'
-Replaced Ignition Module in Distributor (ran fine after replacement for 3 outings-1 hr each time)
-Ignition wires look good, insulation looks almost new (checked ignit wires at night with engine running, looking for arcing, NADA !)
- Not sure about Coil wire from Coil to Distributor. Never replaced.
-Vacume leak? No idea, and no idea how to test

Hopefully, going to check engine spark this w/e with in-line plug tester. Will test at spark plug first, then move back to Coil.

Interestingly, I called one of the biggest marinas on gthe Lake, and they said they've had a recent request for Coils, and can't keep them in stock fast enough.

Will report back to Forum test results.

Thanks,
Bigdog

[MAXUM]

With the plug wires, if you can see an external arch that means they are really in bad shape, however you may not see a bad on bleeding off partial current with the naked eye. If however this was a problem I would have expected that even with the replacement of the module this behavior would have continued to some degree.

Bottom line, hard to give you advice on what to look at next without some additional information.

[Irrigation Guy]

I'd put a set of ignition wires to it, especially since it sounds like you never have. They are not huge $$, and will eliminate a possible cause. Also, other tune-up parts if not previously replaced(cap, rotor, and plugs). I'd also change the water seperator(empty into clear container to check for water sinking to bottom), and fill with fresh gas(hopefully you'll then have a good percentage of new gas).

Please let us know how you make out.

[bigdog]

To Local Realtor

Have never changed ignition wires since I owned boat. Boat is 15 yrs old, I have owned for 4 yrs. not sure of what was done by previous owner(s) ?

Boat actually has low hrs. Only 200 +/- on meter.

Did perform the gas check for water in gas, but couold not see any visible signs being present.

Got an estimate for new Ignition wire set from marina, OEM for $65.

Can I use a standard automotive set of ignition wires from NAPA or similiar
to fit my Merc 4.3LX. It's basically a Chevy 220HP ?
Think wires are either 7 or 8MM Dia. ?

Just thinking it would probably be a lot cheaper buying from automotive parts store than marina.

Thoughts anyone?

Thanks,
BD

[robmac]

yes you can get them from NAPA, alot more cost effective.

[Irrigation Guy]

Yes you can use ones from NAPA, but beware of ones you must assemble yourself or other cheap one. If you are buying quality ones, which I hope you would, you will not save a ton of money on them vs marine quality ones.

IMHO, I would spend a little more for quality you will not be buying them again for a while.

[robmac]

I have a question, what ignition coil do you assemble? Having been in the business for over 35 yrs never bought or installed a coil kit so just wondering.

[Irrigation Guy]

Originally Posted by robmac

I have a question,what ignition coil do you assemble? Having been in the business for over 35 yrs never bought or installed a coil kit so just wondering.

LOL....I think he asked about buying ignition wires at napa, so I replied about ignition wires.

Maybe go back and re-read his post directed to me?

Sorry for the confusion.

[Charlie T]

Got an estimate for new Ignition wire set from marina, OEM for $65.

Can I use a standard automotive set of ignition wires from NAPA or similiar
to fit my Merc 4.3LX. It's basically a Chevy 220HP ?
Think wires are either 7 or 8MM Dia. ?

Just thinking it would probably be a lot cheaper buying from automotive parts store than marina.

Thoughts anyone?

Thanks,
BD

I'd go with the Marina's OEM wire set. Automotive sets are going to be custom length for a Automotive application. The Marine sets are custom length for the Marine application. With Auto wires you will be either too long or too short to properly "dress" the wires in the Marine looms.

On another note and with all due respect, you've been chasing this problem for a year now. I fully understand the "do it yourself" method but if you don't have the real life experience and knowledge to properly diagnose and repair this problem wouldn't it make sense to find a very good marine mechanic that has factory training from your engines manufacturer and have it repaired correctly once and for all? A factory trained guy that does it for a living will probably have an inventory of the proper parts and the proper test equipment and be able get you on the water without further problems. He will (should) also guarantee his work!

The boating season is too short to waste it asking questions on the internet. People here are trying to be helpful but sometimes you need to hear the problem, see the problem or feel the problem in person to know what it really is, suggestions that amount to throwing parts at a problem until something sticks aren't doing you any good. You have a problem that has been difficult to properly diagnose and fix. Internal combustion engines rely on "Fuel, Compression and Ignition" you can change, change,change until you stumble on the problem by accident or you can pay the man once and be back boating and enjoying the lake.

Just my $.02 Good luck with fixing your problems.

Charlie

[bigdog]

Charlie,

I hear ya' loud and clear about chasing the problem, and that's what I seemed to have been doing..... Been frustrating to say the least !
I apprecaite your commnents, TY !

I have sought professional marine help in two instances, In both cases,
the so called 'marine tech professionals' basically just tried to approach by process of elimination, by replacing parts one at a time, taking the
"Let's try this and see what happens" apporach, rather than diagnose the problem from the ground up. The prior appraoch seems to be common across the marine repair business, am I wrong?

That being said, I cannot called these particular marine techs 'Professionals'. I have spent countless $$$, with the 'so called' porfessionals, w/o haiving the issue resolved. I have to take some blame,
I guess for maikng the wrong choices for marine service repairs. 'My Bad' !

Not pessimistic by nature, but who can you trust these days, to stand behind their service to 'do the job right' ? I would place more trust and recommendations, in this Forum from boaters, who may have experienced similiar situations.

I would love to put these engine problems behind me and enjoy the rest of boating season. Continuing to diagnose, will keep Forum informed of progress.

Just my $.02

BD

[Irrigation Guy]

BD...certain ignition only have a certain life span and if you have not changed them I would do so. Even if you consult a professional again, they will likely want to eleminate these parts as a cause and suggest you change them. Why pay a professional to change what you can change yourself?

Cap, Rotor, plugs and wires all fall into this catagory as far as I am concerned. Some of these have a different life span too.

I agree some work is best left for professionals but I try and eliminate some of the easy stuff first.

[bigdog]

OK Forum members, I believe I have identified and fixed my problem.

DRUM ROLL PLEASE !!!! Coil ! No @*^$(*@#$(#&%# Coil !

Yup, I believe this was the underlying issue. Knock on wood !
Many thanks to the following who indicated that this could be the problem:
JRC
NOBOZO
robmac
BroadHopper
Maxum

Although, I believe the 'Ignition Module' I suspect was a contributing factor, being the open circuit board was corroded and rusted electrical wires like threads!

Replaced the Coil shortly after my last thread reply, last week in July.
Have made about 6 boat outings with the family without any engine issues as previously described: coughing, backfiring, stalling

Each outing lasting 1-2 hours of actual engine running time. Engine running at different speeds from wake-speed to full throttle.

Several folks indicated that when the coil is COLD it works fine, but when it heats up,it may be shorting itself out. When engine cooled down it would run fine again. I believe this is exactly what was happening, because this was the exact circumstances.

Also been adding fresh 89 Octane after each boating trip, keeping the tank full. Added Startron to tank, following product mfg. instructions.

So far so good. Hopefully, the problem appears to be now a mute issue.
I will take a picture of Coil to upload and Post. Rusted on outside of body, and inside of terminal tower looked corroded !

Thanks again for everyone input, greatly appreciated !

Bigdog

[robmac]

Glad to hear the issue is finally gone BD now just enjoy the remaining days of the season.

[VitaBene]

Glad you got it- the worst problem was likely doubting your boats reliability.