jeff1000man

Sounds like your MSD box just took a chit. People think that those boxes either work or they don't. THat is not the case. THey sometimes just act up like you are describing.

If you hooked up everything exactly the way you took it out last time, then that is probably what it is. THose boxes don't last forever, and you should always have a spare.

Also check the top of the coil for cracks or burns. Sometimes there is a sprak jumping to a ground on the engine.

Those boxes are also very sensitive to battery voltage fluctuations. Did you put in a brand new battery this year or are you using the old one?

A battery that is getting towards the end of it's life will fry the boxes.

There is a resistor that you can install in line from the power source that will minimize the chances of frying one of these boxes. I don't have the part number, but the best place to start loking is the box itself.

I had a customer that we burned 2 of these boxes in 15 minutes before installing the resistor and now they work like a champ and havn't had any problems, but he does carry a spare, Just in case.

Good luck. Hope this helps.

jeff1000man

That is exactly the description of the problem I had with a boat once that the top of the coil was cracked and causing the spark to jump.

It is the increased load that is causing the ingnition to missfire. If you were to put a smaller prop on the boat, you wouldn't notice the problem until later in the power band. Just some food for thought.

Good Luck.

nocigarette

Absolutly ignition.....( 9 Pounds fuel pressure constant)
I have been fighting a misfire for some time, i have narrowed it down to something voltage related with the msd, everything on the motor is good until i put it in the boat...Dyno was perfect...My box and coil are all new, i had the same problem last year and replaced the box and coil still to have the same problem......It has to be in the wiring, i just have to find out where??
KEEP THE BRAINSTORMING COMING THANKS GUY'S.....

nocigarette

i had the same problem after two coils........I will get it........

nocigarette

What kind of resistor, i have never heard of adding one of these....??

jeff1000man

I will have to look up the part number.

If it is not the box or coil after you change them, try under the cap. Under load it could be crossfiring to a header, you could have a bd wire.

But I am starting to agree. If you took all of the exact components from the dyno to the boat, then it has to be related to your rigging. How old is the battery,

Also, does this problem occur when you are running things lie the radio, amp's, lights, bilge pumps.

Look for consistancies there. Radios and amps will cause interference with an MSD box.

Just thinking out loud, but do your amp leads connect to the same battery as your MSD leads. If so try taking the boat out wiith all accesories except the MSD and regular running wiring hooked up.

Also have your battery checked if it is not brand new. What about the alternator? Is it hooked up properly? could be something there also. Maybe have that checked when you take the battery in.

Good luck. Let us know if any of this helps.

dnebo

Finally someone who agrees with me!!
MSD is old technology.
I currently run old Mercury Ign. electronic with mechanical advance.
I would like to change to Electro Motive Ign. with a crank trigger.

dnebo

I haer an echo in hear Mike.

nocigarette

I think i have found the problem......I need to buy a bigger and faster boat...

nocigarette

You guys are not going to believe this one.....I talked to frank at scorpion racing engines and he told me to switch the two wires coming out of the distributor......I did that, would hardly start, i call him back and he tells me to lossen the distributor until it will and reset the timing.......Ran purrrrrrrfect...............He said that a box will run with reverse polarity....