Engine occasionally dies when coming down to neutral after skier falls

[jwl019]

Need some help troubleshooting a buddies 2001 Malibu 23' Sunscape with dual batteries, only 1 amp, and gps cruise.

A couple weejs ago we went out and the boat ran perfect for the first couple skiers. 2 slalom skiers, then we filled 4 ballast bags with a pump over the side, then pulled 2 surfers before the problem started. Towards the 3rd or 4th pull of the 4th skier the boat shut off when coming back down to neutral to pick up the rider.  Boat fired back up but had a bit of a strange fuel smell. Next rider up, got a pull or two then the same thing happened again. Boat fired back up, got a few more pulls in before it happened again except at that point the boat would not fire back up so we got towed in. Also, when battery switch was turned to 1 or 2, boat would not even come close to cranking, had to be on both.

I also tested the fuel pump and at key up the pressure was correct, still had not cranked the boat yet so haven't gotten a read on it while at idle or running.  Tested the kill switch, it worked correctly, and made sure boat was in neutral.  Batteries in boat tested good, but when we hooked a battery charger up, the boat fired up for the first time in the driveway.  We also cleaned and allied fresh die electric grease to the cannon plug.  Boat ran fine in the driveway, so we replaced the 1 and 2 year old batteries with new interstate batteries and upsized the rated power a bit. Was thinking all was well.

Fast forward to this weekend. Pulled a slalom skier, 2 wakeboarders, then filled 4 fat sacs with the portable pump while the boat is shut off. Get to pulling the 2nd surfer and towards his last set, boat dies coming back to neutral to go pick him up. Batteries were on both the whole time, but boat would not fire up the boat. I switched batteries to #1 and boat fired up with the strange fuel smell again. After cranking I switched them back to both.  It happened one other time thru the day and switching to just battery 1 cranks the boat. Battery 1 is cranking, battery 2 is deep cycle. I put a voltmeter on the batteries at the boat ramp when getting back on the trailer and they were ar 13 5-13.7 so I think the alternator is working.

Other than checking all wire connections, which direction should I head? Which steps for troubleshooting this week should I look at while it is on the trailer?

 

Thanks for any help

[formulaben]

You didn't mention what engine you have.  Not sure if it applies but I'd be looking at the Idle Air Control (IAC) valve.  If you engine is similar to mine it is a quick and easy fix.

[jwl019]

1 hour ago, formulaben said:

You didn't mention what engine you have.  Not sure if it applies but I'd be looking at the Idle Air Control (IAC) valve.  If you engine is similar to mine it is a quick and easy fix.

Been thinking about that or the TPS sensor.

Engine is the Monsoon 325.

[Bozboat]

When the Ignition Control Module under the rotor in the distributor starts to go bad it will quit when hot, when it cools down it will work. One day soon it will just quit. Not to expensive when you get it at the local auto parts store.  I would replace the ICM, the IAC, the coil, and the TPS. Probably the problem is just one of them but I’m not as good as diagnostics and I am at throwing parts at the problem.

[jwl019]

2 hours ago, Bozboat said:

When the Ignition Control Module under the rotor in the distributor starts to go bad it will quit when hot, when it cools down it will work. One day soon it will just quit. Not to expensive when you get it at the local auto parts store.  I would replace the ICM, the IAC, the coil, and the TPS. Probably the problem is just one of them but I’m not as good as diagnostics and I am at throwing parts at the problem.

Thanks Boz, that may be the best route for sure.

[Bozboat]

12 hours ago, jwl019 said:

Thanks Boz, that may be the best route for sure.

The ICM should come with some special grease.  The grease goes on the bottom of the ICM to make a good contact with the distributor.

 

 

[Ndawg12]

Both of my boats have done similar.  If I'm trying to warm the engine quickly while changing the oil in my driveway or surfing/wakeboarding at 3k+ rpm and quickly going to nuetral, the boat drop to around 300 rpm then surge back up to a normal 6-650 range.  A few times I remember it actually stalling but never had a problem restarting or noticed a strange fuel smell.