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no fire to plugs

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redsnapper386

Regular Contributor
guy's,well i thought i was good to go after my last post on coil blow out.my motor ran good on the hose for about 15 min,then it shut down.i checked the coil & had fire,next i checked a few spark plugs grounded to the block,and this showed no fire.so this dist kit is on the way back to the seller for replacement.a new dist should not do this.if it tests out good then what could cause this problem. has any one had this happen,and what was the fix.i have double checked,and checked all wires,and connections,fuses,ect.all is as should be.all other componets on boat work well.i guess the sensor inside of dist could have gone out.once again thanks in advance.
 
unlikely, did you try hot wiring it to see if it would run? TBIV or TBV does not blow a coil or module. With key on, check for 12v at the + side of the coil
 
You need to give more info

What year boat, serial number of engine,

TB IV TB V are considered for discussion purposes JUST electronic ignition. You made mention of a SQUARE coil in your previous thread????

You need to be more specific.

TB IV and TB V used a standard looking coil!!!

Please give us more info!!

WHat do you really have?

If you have a manual it should have the test proceedure for a merc ignition........
 
Ayuh,... If there's Spark at the Coil,...
Everything downstream from it is suspect,...
Coil Wire, Rotor, Distributer cap, or the plug wires...
 
ghost,1987 searay 25',350 5.7,ser no 4100100749.tb4 est-electronic spark timing.the coil is aquare shaped,and has 2-plug inns from the dist instead of the tall round type with ring terminals.i understand that the square part is a magnet.this is best i can discribe.i alsofound out that this dist came out in 1995-1996,which means that it was added to the motor as an upgrade.any way ,after i get it back from the seller i want to pin down why this happened.i also hear from on line research that these tb4s are notorious for my problem.i think the sensor inside the dist cap gets hot,and thats it.this is why i want to consider an hei unit marine rated. i would be out of some $,but i can live with that as opposed to having to call sea tow. ghost,my manual doe's not go into detail on my issue.thanks guys.can someone advise,and reccomend a good marine hei.
 
The thunderbolt ignition has 6 components.
1. distributor housing
2. sensor under cap.
3. rotor assembly
4. cap
5. ignition timing control module
6. coil.

There is a difference between thunderbolt IV and V and one difference is the two plug connector (tbV) vs studs (TB IV) on distributor housing.

Also your issue is not notorious!! It becomes a issue when non marine certified back yard mechanics work on them and screw up the wiring or replace parts with wrong or different ones but have no understanding of what is truly wrong. Just sayin.....

Here is the test proceedure......hope it helps.......


View attachment 2049Attached is the test proceedure for a TB V ignition.
 
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