Jet Boat Chapter 3

The motor is back together and back on the boat. I took it to the lake and ran it about an hour on the trailer to begin the break-in protocol. The engine ran flawlessly at and below the prescribed limit of 3500 RPM for the first hour of break-in. Blair and I subsequently took the boat back to the lake for hour 2 of the break-in which calls for getting the boat up on plane and running at just enough throttle to keep it there with intermittent 1-2 minute WOT (wide open throttle) operation. A slight hiccup happened as we accelerated up into the 4000 rpm range. The engine seemed to stumble a bit, but quickly cleared up and we were on plane. The wind was high that day at the lake and we were only able to run it for about half an hour, as the waves were beating us up badly. We finished the session thinking everything was fine.

The weekend arrived and Blair took the boat to the river for some Striper fishing. He called me to report the boat had gone up river about 3 miles and returned without a problem. When I pressed him, he did say it had stumbled a bit when he left the dock with high throttle in reverse. I remember thinking this is still not right.

Susan and I took the boat back to the lake and tested it again. As we left the dock, everything was fine. After reaching the bouy line, I brought up the RPM to around 4000 and the engine began to fall apart. As the RPMs came up about 4000, it would begin to misfire and the RPMs would drop dramatically, either to idle or stop. I kept trying to get it to come up on plane and after many attempts, it eventually began to function properly. I was able to get the boat on plane and the engine performed a any throttle setting flawlessly for the next hour. 'We probably ran around the lake for 20 miles or so, varying the throttle settings from idle to WOT and everything in between and the engine performed flawlessly. I felt like the engine needed to get good and warm before the ignition fault quit faulting.

I took the boat home and over the weekend, I double checked every connection in the wiring. I also removed and reattached every ground wire to make sure that all of them were properly grounded. I also took apart every one of the modular wire connectors and cleaned every pin with alcohol as per the service manual. I took the boat back to the lake and the same thing happened. Initially, the engine craped out at 4000 RPM, but eventually began to operate as expected. SAME PROBLEM. not solved yet.

There are two components to the electronic ignition system on that engine. The "powerpack" and the "timer, trigger base" I have bought both on Ebay, as they are no longer available new. The next step is to replace the powerpack and then test again. If that test fails, I will change the timer base. I really think it has to be one or the other of those components. More later.