I have a 1994 Sea Rayder jet boat with a 90hp mercury force sportjet. Just had it totally rebuilt up in Crystal River Florida by AAA Outboards. It had blown the head gasket several times at the bottom cylinder. They resurfaced the block, new head 30 and 40 over pistons, bearings etc. That was 11/30/2010.

Last week running great, falls on its face, ran rough back to launch, got it home, pulled plugs, bottom clean, middle some fouling, top covered with molten metal. BUHW plugs, no electrode.

AAA says he thinks trigger is bad, sent continuous spark to plug and fried piston, which would not be warranted for what he just did.

Any suggestions or opinions?

Dennis DiVico 239 313 9058
divicod@embarqmail.com

Woof
You shoulda short blocked it!
At least you would have a warranty.
How many hours on the new powerhead?
Did they clean the carbs?
Does the alarm work?

sounds like a crappy shop to me

oh, you might want to ask about AAA outboards on thehulltruth
bad bad bad

Alarm works, carbs cleaned and rebuilt, what I want to know is, is it possible for the ignition to fry a piston like this, running perfect, then bam. like it sucked a ring or something.

Anything is possible, it sounds like detonation which happens from overheating (alarm would have sounded) Incorrect timing, Incorrect spark plugs or inadequate fuel flow.
It is possible that the timing could go out of whack from an ignition module but not very likely from the trigger.

Check the carb on the bad cylinder.See where the air screw is set.
If the cylinders were bored out 30-40over and they didn't re-jet the carbs THEY screw up.
If the trigger wasn't bad before then it probably wasn't bad when they rebuilt the motor.
Take em to court.J

How will I know if they rejetted the carbs?

Air screw affects idle only on those carbs.
Also oversized O/B pistons compensate for the bigger bore by changing piston dome size, allowing you as a rebuilder to put 1 >030 piston in and leave the rest stock and not have to re-jet.

how did the original P/H fail?

He said they used 30 and 40 over pistons.Not just one.
If they gave you a detailed sales reciept(jets) then they should be listed.
Get the trigger tested,J