Coil

[corytha]

I will be changing my coil tomorrow. After motor runs for 40 min or so it cuts off like no gas. Then when cold starts right up. New carb, new fuel filter, new fuel line and water separator, new plugs and wires and points. Anyone had this happen before?

 

[nnl1987]

You can test the coil in question with a multi meter. Chances are its not the coil, they do fail but rarely.

 

[corytha]

Tested when cold its in parameters. Did not test when hot. Everything else on motor is new. I was running great before, I will check the SP gap as well, I know that can draw more current and make coil hot.

 

[corytha]

You can test the coil in question with a multi meter. Chances are its not the coil, they do fail but rarely.

What else should I look for?

 

[Scott Danforth]

agreed, 99.99999% chance its NOT the coil

follow the troubleshooting tree for the thunderbolt ignition, specifically for the hall-effect trigger in the distributor, called a "sensor" in the parts diagrams.

my guess is your boat has the older 2-wire sensor in the distributor vs the newer 3-wire.

 

[corytha]

agreed, 99.99999% chance its NOT the coil

follow the troubleshooting tree for the thunderbolt ignition, specifically for the hall-effect trigger in the distributor, called a "sensor" in the parts diagrams.

my guess is your boat has the older 2-wire sensor in the distributor vs the newer 3-wire.

1989 3.0.

 

[Scott Danforth]

so you have points, when was the last time you verified dwell with a meter?

 

[corytha]

so you have points, when was the last time you verified dwell with a meter?

It was in the shop in Feb for tune up. I have not tested. Yes points. Runs good when cold WOT(4200rmp) good then when get hot cuts off. Motor temp in normal. Then when cold starts right up and runs good.

 

[Scott Danforth]

get a dwell meter, make sure your dwell is running ~ 32 degrees. then make sure the timing is correct. I believe it was 4 degrees BTDC at idle. however you may want to check that.

 

[corytha]

get a dwell meter, make sure your dwell is running ~ 32 degrees. then make sure the timing is correct. I believe it was 4 degrees BTDC at idle. however you may want to check that.

Thank you.

 

[corytha]

get a dwell meter, make sure your dwell is running ~ 32 degrees. then make sure the timing is correct. I believe it was 4 degrees BTDC at idle. however you may want to check that.

Will that do cut off the motor when running about 1 hour, then when cold works normal?

 

[Bondo]

Will that do cut off the motor when running about 1 hour, then when cold works normal?

Ayuh,..... Welcome Aboard,.... I'd run it til it quits, 'n then start testing,......
At that time, is the coil firing,..??
Is gas coming from the carb,..??

 

[corytha]

New carburetor gas is good. I can see gas when I give it gas. I have not tested the coil when the unit quit. Everything will be running perfectly then all of a sudden it dies out. Then when the engine cool off runs perfect again.

 

[corytha]

agreed, 99.99999% chance its NOT the coil

follow the troubleshooting tree for the thunderbolt ignition, specifically for the hall-effect trigger in the distributor, called a "sensor" in the parts diagrams.

my guess is your boat has the older 2-wire sensor in the distributor vs the newer 3-wire.

If an ignition coil is not working properly, your engine will likely misfire. A misfiring engine results in a jerking or sputtering feel when you are moving at normal speeds. When you stop, a misfire from a bad ignition coil may cause your motor to run roughly, vibrate or shake.

 

[Scott06]

Ayuh,..... Welcome Aboard,.... I'd run it til it quits, 'n then start testing,......
At that time, is the coil firing,..??
Is gas coming from the carb,..??

this - when it quits then see if you are missing spark or fuel. If missing fuel open cap on fuel tank.

If spark is no good start looking into points condenser etc if you get no psark off coil. Spark gap tester is really great to have in your tool box for times like this.

Might also take a jumper wire to bypass the resistor/resistance wire see if you are loosing volts to positive side of coil when it happens

 

[corytha]

this - when it quits then see if you are missing spark or fuel. If missing fuel open cap on fuel tank.

If spark is no good start looking into points condenser etc if you get no psark off coil. Spark gap tester is really great to have in your tool box for times like this.

Might also take a jumper wire to bypass the resistor/resistance wire see if you are loosing volts to positive side of coil when it happens

Thank you. I will be look tomorrow.

 

[flashback]

Seems your hung on changing the coil, I say do it, they are not expensive and your mind will be at ease, especially if it cures your problem.

 

[corytha]

Seems your hung on changing the coil, I say do it, they are not expensive and your mind will be at ease, especially if it cures your problem.

yes, because everything was tuned new in the spring.

 

[corytha]

would the point gap do that only when hot motor?

 

[corytha]

this - when it quits then see if you are missing spark or fuel. If missing fuel open cap on fuel tank.

If spark is no good start looking into points condenser etc if you get no psark off coil. Spark gap tester is really great to have in your tool box for times like this.

Might also take a jumper wire to bypass the resistor/resistance wire see if you are loosing volts to positive side of coil when it happens.

Would this happen even when the motor is cold? Boat fires right up runs good. Then about one hour in it cut off and cant keep it running. Then when motor cool down runs normal.