No Fire/no Spark Thunderbolt
 

I have a 93 baja with 454's. I just bought the boat and when i got home i started it on a hose and it fired perfect. after about a minute it shut off like the ly was turned off, and it owuld not start again. then a few days later i went and started to work on the boat and it started instantly but i only let it fire then i shut it down. i took it out today and put it in the water and it would noit fire. i searched the threads but eveyone is talked about ignition boxes. I only see a coil and distributer on this motor, i dont see any ignition box. Could this be a coil? Thank you for any help!

The first thing I would look at it the pickup sensor in the distributor. Its probably something simple.

Double check the engines large wiring harness plug. A buddy had his work loose 2 yrs ago. Same symptoms as yours. The plug was in just enough to work most of the time, but then without warning, just shut down. dead.

Another thing to check is the grounds for your ignition module. The bracket must be grounded and the black wire. If the engine is stock then it has a module and it is bolted to the side of the exhaust riser.

I have a troubleshoot paper i'll scan and post for ya when I get home. It's shows the process of troubleshooting the TBIV ignition system. Very simple and will tell you the culprit. I've had a similar problem in the past and it was the distributor ignition sensor in the dist housing.

I doubt it's the ignition advance moudule. They are made very well and don't go bad very often. On a stock application they are sometimes mounted on the riser or the back of the cyl head.

I checked the main wirring plug and it looked good, that also happened to my old boat. I stll cant find an ignition module but will look again when i get home. If you post the wrring diagram it may not let me look at it because i am not a gold member. if you want to email that would be great! [email protected] thanks for the help so far!!

Your ignition module looks like part #25 and may be bolted to the distributor
http://www.mercruiserparts.com/Show_...BUTOR%29+TB+IV

or if its bolted to riser, it will look like part #9

http://www.mercruiserparts.com/Show_...+ELBOW%29TB+IV

The sending/pick up is part # 7 and is the most likely cause of your problem.
http://www.mercruiserparts.com/Show_...N+COMPONENTSup is part # 7 and is the most likely cause of your problem.

I would also check for a bad coil.

Try this.
http://www.marinemechanic.com/site/page251.html

rdoactive beat me to it. That link was the same thing I was gonna send you.