cleaning electrical grounds.....

[CliffA]

i want to check and clean all of the grounds for the ignition system on my boat this w/e and i want to be sure i know where they all are....i have a Thunderbolt V ignition system with a knock sensor module.....the engine died on me last w/e while on the water and i had to be towed in....the engine was running great at around 2,800 rpm's until about 30 mins into the cruise and then it died suddenly like someone turned the ignition key off....i checked the throttle lanyard kill switch and is has not been thrown....i have no spark going to the plugs...i had a spare ignition coil on the boat so i switched coils but still no start....i checked the distributor cap, rotor, plug wires, distributor wire connections, ignition module connection but could not find any obvious cause of the problem....i will go through the TB V troubleshooting tree but i also want to do the basics like cleaning all the connections, positive and negative of the ignition components.....i did a quick check of the voltage at the '+' terminal of coil with the key in the 'run' position but it only shows 8.5 volts....it should be 12 volts so i think i have a loose or corroded ground somewhere... i did not notice the tach acting wierd before the engine shut down so i don't think the tach is shorted, but i will check it anyway....i have been chasing an electrical problem like this the past couple years....i thought i had it fixed earlier this year when i replaced the ignition sensor in the distributor.....i have replaced every ignition component now except the ignition control module, so a bad module is likely the problem....when the engine died i opened the engine hatch and found the ignition control module was VERY hot to the touch....i tried to ice it down and even sprayed some water over the module to cool it down (did not get any water in the wire connector).....then i let the engine cool for about 30 mins with the engine hatch open and tried to restart the engine but to no avail....i found a good price for a new module on e-bay for $350 so i ordered it....normal price is around $450 - $500.....i still want to go through the TB V troubleshooting process just to make sure the other ignition components are good and that i am not missing the root cause of the issue....

this is not a fuel related problem...i have been completely through the fuel system....i can see gas being squirted into the carb when the throttle is pushed and i can smell gas so i know the carb is getting fuel.....

the grounds i can think of include:
- engine ground stud on starboard side of engine near starter
- both battery negative terminals
- ground bar on the transom behind the engine (ignition module and knock module ground)
- ground bar for the dash gauges/lighting
- ground terminal on the engine starter
- case ground for the ignition module
- ignition sensor (inside distributer) ground

am i missing anything?

thanks...
cliff

 

[SeaRide]

Cliff,

Sorry to hear about your troubles. Keep us posted.

 

[Gary Hill]

Neutral Switch?

 

[CliffA]

neutral switch is a possibility but maybe a long shot since the engine was in gear and running fine then just stopped dead.....i'll be sure to add the neutral switch to the check list....thanks.....

cliff

 

[Newman]

I have no idea if this would be similar in the marine environment but I thought ignition coils worked off reduced voltage once the engine was running. Like full 12v is sent to coil when cranking the engine to offset the voltage drop from the starter and once the starter is disengaged it drops the voltage to not burn out the coil. I only bring this up as 8.5v at the coil may not be an issue. Good luck with it.

 

[CliffA]

I have no idea if this would be similar in the marine environment but I thought ignition coils worked off reduced voltage once the engine was running. Like full 12v is sent to coil when cranking the engine to offset the voltage drop from the starter and once the starter is disengaged it drops the voltage to not burn out the coil. I only bring this up as 8.5v at the coil may not be an issue. Good luck with it.

thanks....the TBV ignition is an HEI system with electronic spark control that uses a full 12V at the coil both when cranking the engine and when the engine is running.....there is no external resitor wire involved like on some cars......usually only ignition systems that use points will have this resistor wire....these systems use a full 12V to crank the engine and when the ignition key is returned to the 'run' position the voltage is reduced to keep from burning out the points.....i found my batteries were a little under charged....when they are fully charged i now get the full 12V at the '+' terminal of the coil.....

through my trouibleshooting i'm pretty sure i have a bad coil but i have to wait until the new one is delivered before i can confirm that....that is strange because the current coil is less than a year old and probably does not have 20 hours of run time on it.....if it is a bad coil i may have a problem with a bad ground causing the coil to heat up or possibly the voltage regulator in the alternator is pushing out too much voltage, but the dash gauge does not indicate a high voltage output....

the fun never ends....

cliff

 

[Newman]

Good to know. I will keep that in mind. I didn't even think of a points system versus solid state. I'm still stuck in 1986 lol.