Engine won't run after it warms up

[jlfrazier]

Hi, guys, I need a little help. I have a '84 Bayliner with a Volvo Penta A125Q. Over the last three years, I have installed Hot Spark electronic ignition with a new coil,
new distributor cap and plugs and plug wires. I've done a lot of other things to this boat, too, but I think my problem is an electrical one. The last couple of times I've
been on the lake, the boat has started and run good, but after about 30 to 45 minutes of running, it won't start. Yesterday we took the grandkids tubing and everything was fine. We killed the engine to swim a bit and when we tried to go it wouldn't start. I pulled the coil wire and held it close to a ground and all it would do is have a very weak spark every ten seconds or so. This has happened a couple of times before and when I got home I checked all the wiring. I thought I found the problem in loose wires or burnt insulation and repaired them. I didn't find any problems this time. I went out this morning and it fired right up. It seems to have to crank little longer than I think it should, but starts after about fifteeen seconds. Then when I kill it, it will fire right back up. I'm thinking there has to be something that is malfunctioning after it gets warm, but I would think it would happen sooner than 30 to 45 minutes. Any thoughts? I would appreciate any ideas. Thanks

 

[Maclin]

When this happens what are you doing with the throttle? Do you have it open some? Might try throttle closed, hit starter, then slowly move the throttle to WOT and leave it there while cranking all this time, limit cranking time to 10-12 seconds.

 

[jlfrazier]

This boat has always been prone to flooding, so I always leave the throttle closed when cranking, cold or warm. Yesterday, I did check to make sure the accelerator pump was working, but didn't try cranking with the throttle open.

 

[dennis461]

Get your self a timing light that uses battery power. Clamp the sensor on the wire which goes from the coil to the center of the distributer.
When you have a problem, have someone watch the light. It should fire repeatedly with no gaps. If this works, you can rule out spark. Then it's either the fuel delivery system or a worn out engine, compression, blow by etc.

 

[Maclin]

If the engine is flooding you need the throttle OPEN all the way when starting to clear the flooded condition.

 

[jlfrazier]

I'm pretty sure its not a fuel issue. I checked the spark from the coil wire this evening and it is a strong orange spark. Yesterday on the lake it was a very weak,
yellow spark that was very intermittent. What could cause the spark to become so weak after the engine runs for a while?

 

[jester31]

Possibly a bad coil, breaking down when hot?

 

[jlfrazier]

I'm going to take it to the lake tomorrow evening and I'll take the extra coil I have from before I put the Hot Spark electronic ignition in. When the problem occurs, I'll
swap coils and see if that is the cause. I'll let you know what happens.

 

[ffej1010]

You said you checked the engine the next morning and it started right up, did you charge the battery overnight? If the battery isn't being charged, (or over charged and getting hot) you may have enough power to turn over the engine, but it is too weak to power the ignition.

 

[jlfrazier]

The battery had plenty of charge at the time of the problem. Couldn't get it on the lake this evening as I had planned. Will try this weekend.