Ignition problem

I have a 95 Bayliner 2050 capr

I have a 95 Bayliner 2050 capri with a Mercruiser Alpha 1. I installed MSD ignition a couple years ago and it's ran awesome until now. It'll run for a few minutes and lose power until all it'll do is idle. If I give it gas all it does is spark knock like crazy and clunk clunk clunk. Here's the weird thing. If I hit the trim switch on the throttle it takes off and runs perfect until I release the switch and it drops like a brick to idle again clunking and clattering like mad. Where do I start??

"Darren you sound like you may

"Darren you sound like you may have an issue at one of your earth points,12 volt supplies or harness plugs.
Check all of the above, make sure they are all clean, corrosion free and fitting well.
You said that you installed the ignition system, I suggest you recheck your installation and its associated wiring.
It doesnt take a much of a voltage drop to give you problems.
Cheers

Peter C"

"Please excuse my ignorance bu

"Please excuse my ignorance but what the heck is an "earth point"? The ignition wiring is fine. All solid connections etc. I didn't think the MSD was the problem anyway because the thing runs like a champ with the trim switch pressed. Like I said in my first post. take yesterday for example: I dropped the boat in, started it, made a couple low speed circles waiting for a friend to park my truck, he hopped in and we were on our way. we drove about a half mile across the lake and clunk clunk clatter clatter. It dropped down to idle and wouldn't run above idle for the rest of the day without the trim switch pressed. Any help appreciated!"

"Darren:

Earth point is a

"Darren:

Earth point is a Down Under acronym for the electrical ground. Based upon your trim switch connection to the problem at hand, I suggest that you look for an open primary and/or shorted wires on the engine by the slave solenoid.

The wiring for the trim sender and limit switches are routed across the engine to a terminal block by the slave solenoid and circuit breaker. When you press the trim switch, you are basically sending 12 volts to the open or shorted wire to complete the necessary circuit. Chafing and melted insulation can do it.

The trim wire harness should be separate from the main engine harness so I don't believe that it is in the trim harness except there is the purple 12 volt trim wire on the engine. Trace each wire and feel for loose or frayed insulation. Guy"

Thanks for the translation Guy

Thanks for the translation Guy.
I keep forgetting that you guys speak a foreign language ;-))
Cheers
Peter C

"Earth, AKA 'ground' i

"Earth, AKA 'ground' is originally a European term, not just Down Under. Everything electrical references to the core of the Earth, all parts of which are equipotential, electrically. If you understand 'star grounding', you know what equipotential means. Not one physical point, one electrical point for all grounds in a circuit or system.

I guess this falls under "Two (or more) peoples, separated by a common language"."

"Jim

I could not have said

"Jim

I could not have said it better myself !!

Now could you explain "it" for me so I can understand what "it" is .................

Just Kidding.

One thing that makes this discussion board probably one of, if not the best of its type around is the depth of knowledge and experiance of its "Advanced Member", contributors. It never ceases to amaze me.
Keep it up guys.
Cheers From Down Under.
Peter C"

"I wonder if it would confuse

"I wonder if it would confuse anyone if the terms "floating ground" or "floating earth point" were used?

It has been 38 years since the first day of my 40 hours/week year long military SAM radar and missle electronics training. Isrial still uses the same SAM system that I worked on only they improved it and wouldn't sell the improvement back to the USA.

Training was quite in depth as I remember which has bailed me out of just about any and all electrical problems in my boat, cars and home.

By the way Peter, "Cheers" was a big sitcom here in the USA for years. Love the term. Take care everyone. Guy"

"Guy
Its always interesting t

"Guy
Its always interesting the different terminologies used from one part of the world to the other and I do very much enjoy the information gained, as well as the participation in, the Marine Engine site.

Although my background is automotive I love the challenges that are presented when you stick an engine into a marine environment.
What can I say, I love tinkering with boats, currently I am restoring a Bertram 25 Bahia Maria,1970 vintage, with a flybridge powerd by twin 292chevs, quite rare in these parts .

Cheers use to be one of my favorite shows, they tend to show all the American shows over here for a few seasons.
At present we are getting a hammering from the CSI and SVU crime shows.

I prefeer the sitcom's myself.

As I always say
Cheers
Peter C"

"Peter- "Oh, he said the w

"Peter- "Oh, he said the word!"

Guy- Doesn't the word 'boat' pretty much equal 'floating ground'?

I want to harden the circuits in my truck- can you help me?

I work with audio and video equipment and it amazes me that less consumer goods' grounds are floating, considering the chances of equipment being placed in different locations and having ground loops is high. Oh, well, more work for me."

"I thought that boat meant bri

"I thought that boat meant bring on another thousand ?

As for hardening up the circuits in you truck Jim, you could try sending it off to boot camp.........

Sorry about that, just couldn't resist.

Have a Great Day

Cheers
Peter C"

"All right, this thing is real

"All right, this thing is really pissing me off! I have looked at every connection and wire I can gain access to without chopping everything apart on the wiring harnesses. I don't see anything even showing a bit of wear. If anyone has any other suggestions I would appreciate any help I can get begore I end up paying the dealer $120 per hour to figure something so stupid out. I know it's going to be something simple, probably a 5 minute fix, but I hate wiring and I am getting frustrated."

"Darren:

Clear your mind of

"Darren:

Clear your mind of your disdain for wiring. You are only clouding your vision. Since you have checked what you can see, perhaps you should open the taped up wiring on the engine and look closely at the wiring. There is a main ground large wire in the harness that has a number of other smaller ground wires that are crimped and soldered to it that branch off of it. One of these is the ground for the ignition.

Since you said it operates by engaging the trim switch, that indicates there is possible wire chafing occurring in that circuit which runs across the engine harness. The trim switch applies 12 volts to the blue and green wires in that circuit. Trace them from the trim/tilt pump.

Do you have a digital voltmeter? When this problem occurs, measure the voltage at the positive coil wire. Check it while it works to have a baseline to compare.

While it is running right and when it isn't, unplug the trim/tilt cable and see if it starts to stumble or run right.

Did you disconnect the main engine barrell plug and look closely for corrosion between the pins on both ends? Keep searching and pulling on the cables.

Guy"

"I've pretty much given up

"I've pretty much given up. Being color blind red and green and trying to trace wires is nearly impossible. The msd is grounded directly to the battery eliminating option 1. The wires from the trim pump, as far as I can tell, go into a huge wiring nightmare that I really don't feel confident opening. I do have a digital volt meter but with the msd it goes nuts. What is the "main engine barrell plug"? If I know what it is I can check that also. I tugged, tested, wiggled, and at one time while it ran poorly it cleared up for a second and I said "ah hah! gotcha!" unfortunately it never cleared up again so I'm back to square one. I think I'm going to have to take it in. Crap! $$$$$$$$$"