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havasurat27
04-12-2006, 01:40 PM
Maybe someone can put thier finger on this problem. Since I cannot get an appt at JC Marine, Savage, Magic for several weeks maybe some help from all of this collected knowledge and surely years of boating issues that make up this happy place called the Sandbar. Any shots in the dark are appreciated!
Boat: Hallett 240
Eng: GT Perf. 502 carbureted, alum head, MSD ig w/6m-2 box.
Prob: An annoying miss that keeps coming back and now will not go away as in the past. The motor runs perfect through all RPMs under no load but misses under any load. This happened last season on the first trip out and I thought we nailed it down because it went away for about 150 hours. Third trip out this season and it is back again.
Troubleshooting that I did over the weekend: Checked batteries and charging system, carb, did a complete service incl. filters and seperators, new cap, rotor, plugs, wires, checked the MSD wire harness, oil is clean, pressure is good. All things check out but the damn miss will not go away as in the past. Any ideas? MSD Box? :cry: :220v:

Craig
04-12-2006, 01:50 PM
I was having aproblem simlilar to this, it was the ignition switch. Mine would just have a miss out of nowhere. When yours misses, have you noticed if your gauges jump at all?

RAZORSHARP
04-12-2006, 02:06 PM
Flux capacitor.

jimslade
04-12-2006, 02:09 PM
check spark voltage-output

Ziggy
04-12-2006, 02:09 PM
Bigger Hammer?? :idea: :p
Could be numerous things.....At least you have advise from one with a similar issue....give it a try, should be easy job.

havasurat27
04-12-2006, 02:16 PM
All of my gauges were bouncing for a short time....almost like a bad ground. Checked all of the instrument panel wiring and nothing appears out of place. My gauges all read well except for the tach. It still moves around a bit if you hold it a on RPM in N. Could be something to look into. Thanks

havasurat27
04-12-2006, 02:17 PM
check spark voltage-output
Will do....Thanks

havasurat27
04-12-2006, 02:18 PM
Flux capacitor.
I have already tried many different brands of bologna but nothings seems to help.. I am going to have the catalytic converters check though! :rollside:

RAZORSHARP
04-12-2006, 02:20 PM
I'd say blinker fluid, but don't think your model came with them. Freegin' upgrades!

havasurat27
04-12-2006, 02:22 PM
I'd say blinker fluid, but don't think your model came with them. Freegin' upgrades!
LOL

ANXIETY ATTACK
04-12-2006, 02:25 PM
Tap into fuel pressure and read psi under full load, you want to maintain at least 6 to 8 psi at full fuel, if under, you may be experencing a lean miss. if so check fuel pump, regulator, filter and kink lines

Terminal Velocity
04-12-2006, 02:35 PM
is it a MSD crank trigger? I've seen the magnets go bad or twist in the aluminum and give people nightmares.

havasurat27
04-12-2006, 02:37 PM
Tap into fuel pressure and read psi under full load, you want to maintain at least 6 to 8 psi at full fuel, if under, you may be experencing a lean miss. if so check fuel pump, regulator, filter and kink lines
Good info.....all of the old plugs taken out looked lean and clean!

havasurat27
04-12-2006, 02:38 PM
is it a MSD crank trigger? I've seen the magnets go bad or twist in the aluminum and give people nightmares.
Not a crank trigger but it is the magnetic MSD dist. The module is rusted but I hear that they all look like that after a few seasons.

SmokinLowriderSS
04-12-2006, 02:53 PM
I was having aproblem simlilar to this, it was the ignition switch. Mine would just have a miss out of nowhere. When yours misses, have you noticed if your gauges jump at all?
Possibility here, how much voltage drop is there thru the switch? Should be virtually none. Also, double check all ground connections related to the engine, not just at the battery, but the ground cable to the engine block, the MSD box to the block, etc, NO PAINT between the grounds and the engine. A good thing to put under there is a house wiring corrosion inhibitor called "Nokorode". It is a grey paste in a tube, avail at most home improvement/lumberyard stores.

havasurat27
04-12-2006, 09:13 PM
Thanks for the feedback.....I have my work cut out to find the problem before it goes to the mechanic at 75 bucks an hour to do the same thing I would hope to accomplish myself.

mickeyfinn
04-12-2006, 09:57 PM
water in the fuel would be my bet.

Tn_River_Ratt
04-13-2006, 03:17 AM
Check your plug wires Too much resistance? arcing under load?
Wait til its dark and fire it up and look for sparks. I had a similar issue on one of my drag cars. Drove me nuts and back til I found it. and dats my $.02 :220v:

ANXIETY ATTACK
04-13-2006, 06:46 AM
Are you using a billet roller cam, if you are they should of installed a bronz dist. drive gear, these wear over time, especaly running high oil psi, then timing would retard, ( lack of power,slugish throttle responce and a miss) check full advanced timing, should be in by 2,200 rpm or so and I like to see 34 deg total, give or take 1 deg. o ya like said above , confirm quality fuel, no water, take a sample from the filter.

Beer-30
04-13-2006, 07:32 AM
I've seen alot of peeps here having trouble with MSD boxes. If you can bypass that or borrow another to check it - could be that simple. Especially since it is sporadic.

Dave C
04-13-2006, 08:14 AM
Does it miss under load. where exactly under acceleration, crusing, WOT? Many factors differ.
First take a vacuum test both at idle and with RPM. This will tell you alot. Get one of those secret decoder rings from Chiltons, etc. If its not electrical this will spot the problem.
then check:
1) Fuel (dump the contents of the filter into a jar and let it sit, you will see any problem)
2) voltage to MSD (must be 13+ volts while running. Get a tester and start checking voltage along that circuit, before and after box and to coil)
3) magnetic pickup in MSD.
4) ohm test or replace spark plug wires.
5) power valve in carb (will load, hard to spot) Cheap.
6) ohm test then voltage test entire ignition circuit. give it the ol wiggle test too and turn on and off other circuits. (power should not drop too much)
If all this fails, isolate separately (by borrowing one your buddies ;) ) the MSD box, carb, coil, distributor. (in that order)
good luck

kanedog
04-13-2006, 08:15 AM
did you change the plug wires this weekend.....is the cap new this weekend also....I read your post and Im not sure if the wires are new this weekend or not. what kind of cap did you replace the old one with....

havasurat27
04-13-2006, 10:29 AM
did you change the plug wires this weekend.....is the cap new this weekend also....I read your post and Im not sure if the wires are new this weekend or not. what kind of cap did you replace the old one with....
I replaced with all new MSD. Cap, wires, rotor.

RiverRatMike
04-13-2006, 10:58 AM
I would have your MSD box tested.

havasurat27
04-13-2006, 11:03 AM
I would have your MSD box tested.
Any idea who tests them in town?

Havasudan
04-13-2006, 03:07 PM
Let me tell you. Chris & Greg at JC Marine have given me quality work for years. They will pull out my boat , Service it and return it to my house. I was recently in a bind and they made time to addtess the issue. Why look any further.

boater012
04-13-2006, 03:30 PM
get yourself a plug and wire an ignition switch to it. unplugthe wiring harness fromn the boat into the engine. plug in your tester and see if that fixes it. ive seen it quite a few times where the ignition goes bad and people trow all kinds of parts at it before they bring it to me. I seem to get a lot of the problem children here. Anywho try tat first. keep the unit around for future use. i Take mine with every time i go to the river. ive saved plenty of weekends for people by being able to isolate their problem on the spot. Igniton switch: $12.00 Being able to tell whats bad in five minutes time: Priceless!!!! I have one all made up with gauges on a piece of king starboard with an igntion on it. Plus all your buddies could use it when they are having problems! my two round pieces of worthless copper!

havasurat27
04-13-2006, 05:39 PM
Let me tell you. Chris & Greg at JC Marine have given me quality work for years. They will pull out my boat , Service it and return it to my house. I was recently in a bind and they made time to addtess the issue. Why look any further.
I know....they have been doing the same for me for years......They are so good that they are too busy...that is my problem.Thanks for the high hopes though

havasurat27
04-13-2006, 05:43 PM
get yourself a plug and wire an ignition switch to it. unplugthe wiring harness fromn the boat into the engine. plug in your tester and see if that fixes it. ive seen it quite a few times where the ignition goes bad and people trow all kinds of parts at it before they bring it to me. I seem to get a lot of the problem children here. Anywho try tat first. keep the unit around for future use. i Take mine with every time i go to the river. ive saved plenty of weekends for people by being able to isolate their problem on the spot. Igniton switch: $12.00 Being able to tell whats bad in five minutes time: Priceless!!!! I have one all made up with gauges on a piece of king starboard with an igntion on it. Plus all your buddies could use it when they are having problems! my two round pieces of worthless copper!
This sounds easy enough but I really don't understand entirely....please explain a little better if you do not mind.....I am very mech. savvy so it should be easy to understand the concept...Thanks!

uvindex
04-13-2006, 06:36 PM
This sounds easy enough but I really don't understand entirely....please explain a little better if you do not mind.....I am very mech. savvy so it should be easy to understand the concept...Thanks!Pardon me for jumping in here. :)
I think he's suggesting that you get an ignition switch like the one that's in your boat. Wire the same kind of connector to that switch as the one on your boat's ignition switch. This way, you can just unplug your boat's switch and connect the test ignition switch into your boat's wiring harness using the connector that you provided.
Provides an easy way to determine if your boat's ignition switch is the source of the problem without unwiring and rewiring your current switch.
I hope I interpreted his advice correctly. Good luck! :)

havasurat27
04-13-2006, 07:42 PM
Pardon me for jumping in here. :)
I think he's suggesting that you get an ignition switch like the one that's in your boat. Wire the same kind of connector to that switch as the one on your boat's ignition switch. This way, you can just unplug your boat's switch and connect the test ignition switch into your boat's wiring harness using the connector that you provided.
Provides an easy way to determine if your boat's ignition switch is the source of the problem without unwiring and rewiring your current switch.
I hope I interpreted his advice correctly. Good luck! :)I appreciate everyones pointers....It is is much more clear what to do....it makes sense.
I have recieved a lot of great advise with this thread. Bad thing is the boat is at the LHC house and I am stuck here in So Ca so all of these fixes will be taken with me next weekend. I will let everyone know what the final issue was once it has been found.

ColeTR2
04-13-2006, 08:05 PM
A lean condition can also cause a slight miss. Did it seem to go away last year when it got hot outside air temp / Summer? This time of the year the air density is greater. Witch means more air / density mixed with less fuel / lean, this give you a lean condition. This causes a miss, it's like a pop / back fire up through the carb. This will show only when the motor is under a load. Does the spark plugs look lean? I would try putting bigger main jets in the carb. just my .02 good luck. :)

boater012
04-14-2006, 08:05 AM
This sounds easy enough but I really don't understand entirely....please explain a little better if you do not mind.....I am very mech. savvy so it should be easy to understand the concept...Thanks!
The plug im talking about is the plug that goes into the wiring harness on the engine!! Have you seen it??? On Mercruiser engines the plug is usually round. Just follow the wiring that comes into the engine from the boat. I see alot of times where this little tool can be extremely helpful. If you have a hard time finding the plug send me a pm!! I have 5 or 6 in stock right now. Ill send you one at cost. I even have several ignition switches in stock as well. Wouldn't Take me but ten minutes to throw one together for you! pm if you'd like one and ill get it out to you right away!

boater012
04-14-2006, 10:11 AM
Check your P.M's