Now at a lost

[Rihansu]

Was enjoying a ride with the family, suddenly while at full throttle kind of lost half power, i tough i caugth some weed or something, slowed down put the motor in reverse then foward again all seems fine, after maybe 200 yards the motor shut down and would not restart. some maintenance item were due, we change the distributor cap and rotor also the sensor assembly, tried a new coil, checked for the tdc, went thru the diagnosis chart to see everythings is receiving current as it should,also change the gas filter (wich was nice and clean), Carb is getting fuel, battery fully charged, really went thru everything. Now the motor crank but no start condition the only thing left would be the thunderbolt IV ignigniton module wich is supposedly very rare to fail. Forgot to mention kill switch tested fine and i have no lanyard kill switch or button...

 

[alldodge]

Howdy
You mentioned a TB-IV so I'm assuming its a carb Mercruiser of some kind and year. Can you help a bit more and say what motor and year?

Do you have 12V at the + side of the coil with the key ON?

When you pump the throttle, do you see gas squirt in the carb?

 

[Rihansu]

Sorry forgot to mention it s a mercruiser thunderbolt 230-v8 serial 8603441, boat is 1989 Peterborough, to answer yes fuel gets to the carb alright and yes i ve got power on the positive side of the coil, I can even make the coil spark touching the white-green wire from the switch or with the test light touching the positive side of the coil with the key to the on position.

 

[alldodge]

or with the test light touching the positive side of the coil

Now coil shouldn't spark with touching the + side with a test light. That is different, but the white/green is good.

Disconnect the White/Green wire going to the shift interrupter and the Gray wire on the - side of the coil. If you don't have a tachometer then there may be no gray wire

 

[Rihansu]

I do have a tach...​

I ve got two gray wire on that side of the coil will test each one in turn and disconect the kill switch and let you know… Thanks for the help

 

[Rihansu]

Getting something different at last, There are two wire on the same spot at the switch, disconnected only the wht-grn, on the negative side of the coil disconnected the one that goes into the harness wich should be the tachometer since the other one goes into the ignition module, while cranking i m getting a puff at the carburator.

 

[alldodge]

Even though you have a 1988 boat your motor is a 1987 model. There should be 2 wht/grn wires coming from the distributor and one goes to the interrupter and other goes to the TB-IV module. So when either of the wht/grn wires is struck against ground, it should cause the coil to spark. The interrupter holds ground just a tad longer which causes the motor to stumble so it can be shifted out of gear

What I think is happening, is either your module is starting to fail, a bad connection, or pickup module is having trouble

 

[Rihansu]

Think it s the module that s going, Gone to try to find one and switch it to see, boat yard must have one laying somewhere...

 

[alldodge]

You can still get the distributor pickup 87-892150Q02 but agree the modules are harder to find.

 

[Rihansu]

Forgot to mention we changed the pick up at the same time as the rotor. Before looking for the module i ll make sure myself that everything is aligned properly for the timing. My daugther and son in law are car mecanics they were doing their best but while revising what they done found a few mistakes in connections, so i ll recheck everything before heading for the boat yard.

 

[alldodge]

Just a note when your looking around, you can install a TB-V where the IV is if need be. Will need connectors to rewire and need same advance curve. Your module will have V8- something like 20 or 22

 

[Rihansu]

Update… checking everything my self was a good idea: found the distributer shaft have been put 180 degrees in, Saw on the internet that if it does not start and putter at the carb to switch it 180. Now start like a new just the fine tuning to be done… thanks for the advices and help

 

[Bt Doctur]

Sorry, that not the way a dist works. Unless you pull it to replace the module and installed it 180 out. it dosent just jump timing

 

[Rihansu]

Yes we pulled it all out since it was an original sensor full of corosion as the shaft inside the distributor we cleaned it and change for the new model and that shaft been inserted in the wrong direction, now it's start like a charm.