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

[bigdog]

MAXUM,

Not sure about that 'Ignition Pickup' ? I do know I Marine Techs replaced:
Distributor Points/Rotor, Condensor...... Nothing mentioned by Techs, about 'Ignition Pickup' to me? Does not seem like a DIY project for backyard mechanic?

About the Coil, 'either working or not', the Forum comments have indicated that whne these things 'heat up' they can short and cause problems like what has been described.

Coil is original (1995), boat also was in and arround 'salt water' at different times.

Does the Forum still stand on their opinion about the coil issue ?
MAXUM makes a good argument about the coil and 'ignition pickup' issue!

Also, just more FYI about engine.
- Changed Plugs mid-last season. BTW old plugs looked pretty good !

Past symtoms of engine 'fuel starved' seems reasonable, as 'Acres Per Second' described: coughing, stalling backfiring. This was happening last season ! Replaced 'electric fuel pump' (wasn't cheap !), end engine ran much better. I was told by marine Techs, that the Pump contains a 'sliding ball' which can stick or totally locks up (thanks Mercruiser ! ) causing fuel starvation to Carb !

More thoughts anyone about the Coil replacement and cause?

Thanks,
BD

[bigdog]

MAXUM,
Do you think the soldered connection points on Ignition pickup. can be cleaned and reinstalled ? Or is complete replacement of this part required?
Your thoughts ?

FYI, getting to my Distributor in engine compartment, is like having to balance on my head upside down.

Damm those boat design engineers ! They don't think of accessibility by the boat owner to perform maintenance ! No thiought put-in when designing boat/engine layout.

Thanks again.
Bigdog

[MAXUM]

Honesty I don't know and my way of thinking is if the part, especially electronic is in any way faulty why not just replace it. What I didn't tell you was that it took me several trips out on the lake to figure out what the problem was and twice had to be towed in, thankfully I did not go out alone so the towing was somewhat expected. By that time whatever I found to be wrong was definitely going to be replaced.

I'd at least pull it out and look at it although some may not have outward signs of being bad, mine it was plain as day. The service manual I have does not give any kind of diagnostic tests that can be done. Granted I have a cheapo Clymer manual, if I had a mercruiser manual I'm sure it would have a test that could be performed with a multimeter to ensure it's within spec. Also what makes me think this may be an issue is that 99% of the problems I've dealt with in regards to ignition module failures (oh I'm an ex Toyota technician) has been heat. Things are fine till you hit operating temperature then the sporadic run time problems rear their ugly heads.

OK far as coils go. Again usually when they go they just plain go. Be aware that there are various makers of coils out there, some good, some not so good. There was mention of Mallory in an earlier posting. Don't know about them but I'd stick with a Delco or Denso. If you are going to put a new one in, before going through all that work to install it, shake the coil and be sure it's got oil in it. Matter of fact I do that at the parts store!

The ignition pickup is inside the distributor housing. At least that's what I've always called it, looking in my service manual they call it the ignition sensor, the box it came in something like ignition module assembly. Call it what you want I guess. If you pull the cap off and pull the rotor off you'll see it, there are a couple of small screws that hold it in place and there is a notch in it where the rotor blade rotates through. Yes these are not exactly easy to get to depending on the way your boat is made. I'm fortunate in that I can pull the engine box off and get it out of the way and lift the rear sun pad out of the way. For those that have the bench seating, yeah it's a chore. Replacing the part is not hard and takes little mechanical know how, just need to get in there which is half the battle. For reference I have a 2003 4.3 with the thunderbolt solid state ignition and no EFI. If it weren't such a pain to get at it I'd pull my distributor cap and take a pic for ya. I was just out in the garage looking for the original box it came in so I could give you a part number, but it looks like I may have pitched it.

BTW if you're going to go that far might as well replace the rotor and cap too. I did just because I was already in there.

Good luck!!

[bigdog]

Thanks again MAXUM. WOW a Toyota Tech Rep. impressed !

What you've desribed about 'ignition module assbly' makes sense to me.
I've heard repeated stories about this problem from many sources, both here on Forum and other boat owners..

Will inspect that ingnition module for corrosion, and also check online for replacement part and cost. Will probably buy at local marina !

Honestly, I havd never known anyone who had to replace their coil.. Not saying it doesn't fail, but seesm like an unlikely cause, compared to 'Ignition Module'.

Thanks,
Bigdog

[MAXUM]

Originally Posted by bigdog

Thanks again MAXUM. WOW a Toyota Tech Rep. impressed !

What you've desribed about 'ignition module assbly' makes sense to me.
I've heard repeated stories about this problem from many sources, both here on Forum and other boat owners..

Will inspect that ingnition module for corrosion, and also check online for replacement part and cost. Will probably buy at local marina !

Honestly, I havd never known anyone who had to replace their coil.. Not saying it doesn't fail, but seesm like an unlikely cause, compared to 'Ignition Module'.

Thanks,
Bigdog

No problem. Hopefully that cures your ailing boat! Used to be a Toyota tech, wrenched for a few years, got bored with it and did a career change. Still do it though, just not for a living.

Good luck with your repair. Let us know how things turn out.

[XCR-700]

Originally Posted by MAXUM

Honesty I don't know and my way of thinking is if the part, especially electronic is in any way faulty why not just replace it. What I didn't tell you was that it took me several trips out on the lake to figure out what the problem was and twice had to be towed in, thankfully I did not go out alone so the towing was somewhat expected. By that time whatever I found to be wrong was definitely going to be replaced.

I'd at least pull it out and look at it although some may not have outward signs of being bad, mine it was plain as day. The service manual I have does not give any kind of diagnostic tests that can be done. Granted I have a cheapo Clymer manual, if I had a mercruiser manual I'm sure it would have a test that could be performed with a multimeter to ensure it's within spec. Also what makes me think this may be an issue is that 99% of the problems I've dealt with in regards to ignition module failures (oh I'm an ex Toyota technician) has been heat. Things are fine till you hit operating temperature then the sporadic run time problems rear their ugly heads.

OK far as coils go. Again usually when they go they just plain go. Be aware that there are various makers of coils out there, some good, some not so good. There was mention of Mallory in an earlier posting. Don't know about them but I'd stick with a Delco or Denso. If you are going to put a new one in, before going through all that work to install it, shake the coil and be sure it's got oil in it. Matter of fact I do that at the parts store!

The ignition pickup is inside the distributor housing. At least that's what I've always called it, looking in my service manual they call it the ignition sensor, the box it came in something like ignition module assembly. Call it what you want I guess. If you pull the cap off and pull the rotor off you'll see it, there are a couple of small screws that hold it in place and there is a notch in it where the rotor blade rotates through. Yes these are not exactly easy to get to depending on the way your boat is made. I'm fortunate in that I can pull the engine box off and get it out of the way and lift the rear sun pad out of the way. For those that have the bench seating, yeah it's a chore. Replacing the part is not hard and takes little mechanical know how, just need to get in there which is half the battle. For reference I have a 2003 4.3 with the thunderbolt solid state ignition and no EFI. If it weren't such a pain to get at it I'd pull my distributor cap and take a pic for ya. I was just out in the garage looking for the original box it came in so I could give you a part number, but it looks like I may have pitched it.

BTW if you're going to go that far might as well replace the rotor and cap too. I did just because I was already in there.

Good luck!!

I too have had problems several times with the ignition module inside the dist on my 23' Carlson 5.7 Mercury I/O with thunderbolt ignition.

Its a piece of JUNK as far as I am concerned and part of the reason that boat is down with a bad motor.

The module died while I was prepping it for winter and I thought well its good enough and I'll fix replace the module again (3rd time for me) in the spring. Well I guess I didnt get enough coolent run through it and the motor got a freeze crack,,,

What really got me was that the motor had very low hours and ran GREAT otherwise. Errrr

[Baja Guy]

Here is a link to free downloads of the Mercruiser factory manuals. Find your year and engine and it will show you what the part Maxum refers to looks like and how to change it. http://forums.iboats.com/showthread.php?t=342393
To do that service be prepared to use a pair of screwdrivers to 'leverage" the rotor off the distributor shaft. Mercruiser says that's how you take it off. It's done that way because the rotor is stuck to the distributor shaft with Locktite.
You can inspect the ignition module without removing any parts though, I'd say do that first. All you do is lift the distributor cap far enough to see inside the distributor. You can do that with the plug wires still attached if my 5.7 with Thunderbolt ignition is any guide.
I believe Mercruiser says to check for a good solid connection from the sensor to the board. The connection can fail and split, in which case you can get intermittent problems like Max had.

I found corrosion on the underside contacts of my distributor cap this spring. Check that too. I agree with doing the cap & rotor as a preventive step. They cost about $40 for the set.
I'm with Maxum, fix it as soon as you even think it's a problem, that way you don't need a tow home or worse.

Pete

[chunt]

I had the same problem, the boat will not rev up after warm. Found the thunder bolt ignition module was the problem. It is bolted onto one the heatexchanger manifolds. The trigger from the pickup, inside the distributor, goes to this module. It contains the advance curve and triggers the coil to fire. I found the problem by putting ice on the module when it was hot, this allowed th motor to rev up again until it overheated again.

[Baja Guy]

"Cool" diagnostic technique, I couldn't resist...where did you get that idea?

[bigdog]

Regarding the gnition Module Assembly...

Wow, never knew this little part (Ignition Module), have caused so many issues, for so many people ! Some of your stories must have been frustrating, especially if you got stuck and had to be towed !

FYI, Distributor Cap & Rotor changed last Fall.

Well, I was able to get to my Distributor. Had to dismantle several pieces of couling/covers around the engine. Like I said, my engine compartment is extrmely difficult to work around. Even with these pieces removed, I don't have a easy access to the Distributor.

Distributor had three screw type bolts which holds it in place. And one phillips type screw, also on the cover which didn't look like the others ? Not sure what that screw is for?

Pulled Dist. cap off with plug wires intact. I can see inside the Dist., and see Rotor on top. I cannot see anything else ? I tried to pull off the Rotor, but it didn't budge. I think I remember that someone said that it may be held in place with 'Locktite' ? Anyway this is as far as I got, and had to stop cause of darkness.

Afraid to pry-off Rotor with 2 screwdrivers as somene indicated. for fear of breakage ! That wouldn't make my week !

At this point I may haul boat to marina in Gilford area, to have them complete the job. Everything is basically dismantled at this point, and think marina should be able to install the Ignition Module in less than an hour ?
Ya Think?

The only problem now, is finding a marina that will do this now, just before the 4th of July holiday w/e ?

Going to make some quick calls in the morning to see which marina can accomodate.

Oh, A BIG THANKS 'Baja Guy' for sharing that Mercruiser shop manuals with the Forum ! http://forums.iboats.com/showthread.php?t=342393

BD

[bigdog]

News Update !

Got new 'Ignition Module' installed !!!! Yippee!

Inspected old Module, and appeared to be rusted, pitted, with white-greenish corrosion on contacts. What a piece of JUNK Merc made for this part !
Basically, and open circuit board, with wires. Apply moisture, and you've got some real problems. New Module encased in Resin, so Merc must have know they had a problem with the original design.

Hoping this was the problem, and the fix, and can put this issue to sleep, once and for all ! Crossing my fingers, and saying a prayer.

Will test boat on water probably Thur.

BD

[NoBozo]

Originally Posted by bigdog

News Update !

Got new 'Ignition Module' installed !!!! Yippee!

Inspected old Module, and appeared to be rusted, pitted, with white-greenish corrosion on contacts. What a piece of JUNK Merc made for this part !
Basically, and open circuit board, with wires. Apply moisture, and you've got some real problems. New Module encased in Resin, so Merc must have know they had a problem with the original design.

Hoping this was the problem, and the fix, and can put this issue to sleep, once and for all ! Crossing my fingers, and saying a prayer.

Will test boat on water probably Thur.

BD

Excellent news BD. Stay close to home until you are positive...Yeh Yeh..I know...maybe a better word is Comfortable...before you venture out beyond paddling distance....unless you are sure of a (FREE) tow. NB

[bigdog]

NoBozo, good advice ! Wil stay close to home port for a while.

Will have wife on next boat outing, so sure don't need to breakdown.
She's insisting on going on trial run ! I warned her the possible consequences.

I'll be bringing my 1/2" wrench just in case..... If engine produces same symptoms, the brass plug will be pulled in the middle of the Broads !


Wife and I are just about ready to switch to 'Sail' after this !

BD

[MAXUM]

Bigdog-

Based on your description of the old module I'd say you found your problem. Awesome, glad you got it fixed in time to get out there and enjoy the lake!

No question that old module was a bad design, not sure if it's something that is unique to just Merc or if Volvo suffers from the same flaw. They do after all use the same 4.3L Chevy engine. How much similarity there is between the two would be interesting to know. I can't imagine the ignition systems are all that different between the two. What ever the case the new design is far and away superior to it's predecessor.

[NoBozo]

Here's a GOOD site to find Mercruiser Parts with Prices. This is not a discount place but offers what I believe are Retail Prices so you can have a starting point when shopping for parts. NB

http://www.mercruiserparts.com/mercruiser_parts.asp

[MAXUM]

Originally Posted by XCR-700

I too have had problems several times with the ignition module inside the dist on my 23' Carlson 5.7 Mercury I/O with thunderbolt ignition.

Its a piece of JUNK as far as I am concerned and part of the reason that boat is down with a bad motor.

The module died while I was prepping it for winter and I thought well its good enough and I'll fix replace the module again (3rd time for me) in the spring. Well I guess I didnt get enough coolent run through it and the motor got a freeze crack,,,

What really got me was that the motor had very low hours and ran GREAT otherwise. Errrr

XCR-

Food for thought. When I winterize my boat I completely drain the block and manifolds of as much water as I possibly can, then backfill with antifreeze, the RV/Marine stuff since it's non-toxic. Now I'm not sure where the drains are on the 5.7, but the 4.3 I have has a total of 5 drain plugs. One on either side of the engine block, one on the bottom of each manifold and one just below the water pump next to the fuel/water separator.

Once I have all the raw water drained out I put the plugs back in then remove the top side of the coolant hoses on the front of the engine. They all come together onto what looks like a distribution point, I think (going off memory here) there are 4 total, two that are small and two that are large. Anyways I backfill the engine block by pouring the antifreeze into those hoses till they are full. One of the smaller hoses goes directly to the stern drive so after pouring antifreeze into that hose for a bit you can hear it dripping coming out the raw water intake. When I do this I already have the boat and trailer in the garage and up on jack stands with the stern drive as far down as it'll go without hitting the floor. I store it all winter like that. Never had any freeze up problems and I can tell how much antifreeze is in the engine block and manifolds based on how much I put in which is usually at least 2-3 gallons. Now some say you can just drain the engine, manifolds and that's good enough, maybe but any untreated water left over will freeze and depending on where it is could cause problems so I figure it better to be safe than sorry. Antifreeze is cheap, engine blocks or stern drives not so much!

Oh I forgot the most important part!! All that water and what little antifreeze may spill into the bilge should be cleaned up - then optionally wax the bilge so it's nice an pretty to look at

[robmac]

I agree,when I winterize I go and get 6 gallons of RV antifreeze. I run 3 through the engine pull the drain plugs let her drain completely then pull a top hose and run 2-3 gallons back ib. Been doing that for 20 plus years and never an issue in the spring. Depending on where and how bad she's cracked you can have it welded. Did it a couple of times with race engines,it's a pain but not as bad as paying to replace.

[bigdog]

Reporting back to the Forum on test run....

Replaced 'Ignition Module Assembly' at the suggestion of a few on this forum.
Again, when I removed the original part, I was shocked to see this part
'basicall an exposed printed circuit board'. are you kidding me !
At least the new design of this part is encased in resin, totally protected from the environment or heat.

The maine engineer geniuses really blew this original design ! All those years studying at an engineering college and all that money for tuition.....
and that was the best design they could come up with..... Amazing !

I digress...... Back to the results......
Have taken boat on trilal runs now 3x, for more than 4hrs. Various levels
of speed/RPM's. NO ISSUES ! PTL !!!

Previous boat outings have produced engine caughing, backfiring, and stalling after only 20-30 min of use. Almost needed a tow a couple time, but was able to limp back to port.

Hopefully, this issue is finally resolved !
Guess I can put away my 1/2" wrentch, and thoughts about pulling the plug ! At least for the time being..... TBD..........

Oh, one last mention about Winterizing engin I'd like to get folks thoughts.

My guy who winterizes my boat, also runs a car dealership.
He just drains all headers, hoses, and any other orifices of water. He does not add anti-freeze, never has. His thoughts are, if there is no water in the engine, there is nothing to freeze ! Says he' never lost or had an engine crack as a result of this process yet ! Thoughts ?

Thanks everyone for all the advice, especially to MAXUM, who I believe
came up with the original diagnose, only through a similiar situation.

BD

[BroadHopper]

I usually run 4 gallons of antifreeze and forget the draining. Never had a problem. Advantge of keeping the antifreeze in the motor is a rust preventative. There is no air in the block to form rust.

[NoBozo]

Originally Posted by bigdog

The maine engineer geniuses really blew this original design ! All those years studying at an engineering college and all that money for tuition.....
and that was the best design they could come up with..... Amazing !

IBD

When we designed that module, the "Bean Counters" wouldn't let us encapsulate the circuit board because:

1. It would be Too Expensive.

2. Encapsulating the module would violate the Laws of Planned Obsolescence and the module would last longer, thereby slowing down future sales NB

[RI Swamp Yankee]

Originally Posted by bigdog

.... when I removed the original part, I was shocked to see this part 'basicall an exposed printed circuit board'. are you kidding me !
At least the new design of this part is encased in resin, totally protected from the environment or heat.....

Sorry if this is a bit off topic but several years ago I had alternator problems with a Dodge Caravan. It would fail to charge ONLY when the weather was wet!!! ... long story short ... I found part of the engine control circuit board that controlled the charging was not encapsulated, the rest of the board was ok. Dried the PC board, encapsulated it and end of problem.

[trfour]

[QUOTE=bigdog;131248

"Coil is original (1995), boat also was in and around 'salt water' at different times."

Thank you... Very important to give us an idea when asking for help to give the year that the boat was manufactured...

Worn distributor shaft bushings can cause a multitude of problems and can cause the rotor to strike the distributor cap contacts, usually dislodging the rotor contact plate and causing erratic ignition timing problems... [ Kind of like inhaling cheerios for us humans ]!

Now,... I know that nobody wants to listen, however, the time to do basic maintenance and check your anti tow vehicles life line, is during off season. Shrinkwrap ain't going to get her done!
However, should you like paying a higher premium, and enjoy Company, tow US is not far behind.

Auto, boat, car, heilicopter, plane or truck, got my fix in and on route 66.
Last, but NOT least, just wanted to say a Big HI, to the Noonan's!!!!
tenfour?

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T