1990 bayliner 4.3l gen2 engine quits

[mesaroper]

I have searched this forum, but cannot seem to locate a problem that matches mine exactly. Boat will start and run fine then will shut off as if I turned the key off, no sputtering or anything. There seems to be plenty of fuel entering carb, I am thinking it is an electrical problem. Boat ran fine last season, on first trip out this season it ran most of day then problem started as I was heading back in to dock. It will started easily after shutting itself off, runs 2-5 minutes then shuts down. Seems when something warms up causes the shutdown. Not sure what info you guys need so please let me know and I will provide, thank you

 

[tpenfield]

First thing that I would check is the kill switch to see if that is becoming temperamental. Then move on as needed to electrical connections for the ignition key and the connections at the engine, etc.

does the accessory power stay live when the engine dies, or do you loose everything?

 

[mesaroper]

Thank you for fast response! I engaged kill switch a couple times and it seems to be working, but I can't rule out as the problem yet. The accessory power does stay live. I have been working on this problem today and found if I restart boat it dies more frequently which leads me to believe heat is involved.

Some more info: Thunderbolt IV ignition

 

[mesaroper]

Okay, so I have run a lead from coil to key switch and now can keep engine running. I believe I have isolated problem to purple wire between coil and key switch. Can anyone help me with components that would be on this line? Again, this is a 1990 Bayliner Capri 2050, 4.3l Mercruiser,Alpha One Gen II, Mercarb carb, Thunderbolt IV ICM.

 

[Bondo]

Ayuh,..... Welcome Aboard,..... Start with the cannon plug that connects the motor to the hull, found on the motor,...

Loosen the hose clamp, pull it apart, 'n look for corrosion,...
Clean up both ends, you can open the pins a tiny bit to give better bite in the holes if ya want, but just a tiny bit, or it's hard to push back together,...
I grease it, stuff it back together, 'n tighten the clamp up,......

 

[mesaroper]

Thank you for taking time to answer my post Bondo,

So I took plug apart and lightly sanded both sides. I don't have grease available today, but will get some ASAP. The result was that my boat run at all rpms for 15-20min, maybe longer vs. 2-3 minutes. In the plug pin number 4 appeared slighltly loose in plug and there appeared to be a slight "smudge" around base of pin. I will search here for that pin number wire color, but if anyone can point me to a diagram I would greatly appreciate, thanks.

 

[mesaroper]

UPDATE: So I have found that when I loose voltage between coil and key switch, I will have voltage on purple wire at key switch but no voltage on either side of the cannon plug or at coil. I briefly lose voltage then it will return. So am I right believe the problem will be found on purple wire between the key switch and the cannon plug? Would the neutral safety switch be on that circuit? Engine to dash wire harness replacement?

 

[mesaroper]

PROBLEM SOLVED: Well right wrong or otherwise, I determined that the purple wire from the ignition switch to the coil had some kind of fault. I run another wire from ignition switch to coil and left original purple wire on circuit. Boat runs fine now. I am not sure this is an acceptable repair for true mechanic, but wasn't sure what else to do. Neutral safety switch performs as it should with this additional wire on circuit. Any thoughts appreciated

 

[achris]

Put a test light on the coil side of the lanyard safety switch (not neutral switch). If the light stays on, problem is probably in the plug and socket. Light goes off, switch is intermittent. Pin 5 is the purple wire.

Chris.......

 

[mesaroper]

Okay. so I feel like this might qualify for Stupid Human Tricks while boating, but will go ahead and fess up and maybe save somebody else a little trouble. Turns out it was the lanyard/ignition kill switch as pointed it in the first response. I tested as suggested in previous post and found switch to be intermittent. I appreciate all the help and you guys taking time to keep up with this forum!