Won't start when warm

[Economacki]

Just found this forum, and I hope you folks may shed some light on my particular problem. I wasn't able to find a similar problem on the search function.
So- my 140 Mercruiser will start in a second when cold. When running (well) for about 15 minutes, and shut-down, it will not restart,(no spark) until cool. I've changed-out the coil,points,condenser,rotor,dry gas. The boat was in my garage the whole of last year, due to a rainy summer in these parts (NW Pa.).
Any thoughts?

[JonathanCole]

If it is true that you have no spark in warmed up conditions, and you have replaced the items mentioned, then you should think about what heat does (cause expansion) and how and where that might interrupt the circuit to the coil, points, plug/plug wires. If a connector is corroded or broken inside of insulation, often times the heat of running can cause an open circuit due to thermal expansion. Check the continuity on all the wiring in the ignition system when it will not start. Don't forget continuity to ground. Alternatively, a starter/solenoid that draws too much current can deprive the ignition of current sort of like a lesser short circuit.

[tom kane]

Perhaps your coil is getting to hot,this makes induction coils very inefficient.

[woodboat]

Did you buy the proper coil. There are internal and external resistance coils. Which do you have? Which do you need?

[gonzo]

Changing parts without troubleshooting is a very expensive way to fix a problem. Also, if the cause of the problem still exists, you may damage new parts. Warm up the engine until it doesn't run and test for power with a test light. Measure coil primary and secondary resistance and check they are correct. The ballast resistor, or lack of, can also be a problem.

[Economacki]

Thanks for the replies and the suggestions offered. I've been traveling, but will use your thoughts this week & see what happens. I'll report on what I hope is a solution.

[Chrisstopher]

I know this thread is a year old - but i have exact same problem - no start when warm. '86 3.0L Mercruiser, 4-cyl GM with carb and points. Fires instantly when COLD with 3-5 pumps on throttle.

Once warm, have tried no gas (in idle position), 3-5 pumps, constant pump and wide open. Will always "eventually" start but i'm wearing out parts fast.

Economiser - did you find a good solution? Any other suggestions?

thanks much for your help. Family will not go out with me again until fixed (can't say i blame them!)

Chris
Madison WI

[tdomi2]

sounds like a bad condenser.