Battery Ground Came off 454 Merc running offshore...

[BajabossJD]

Hey guys,

New here. I picked up a 23' Baja 2 weeks ago. It has a carb 454 Bravo 1 with a Thunderbolt IV. I was running about 4k RPM's over some 3' er's on the 4th of July and somehow, some bottled waters got back in the engine bay and knocked the ground off the battery. The tach pegged to 7k rpm and the engine shut down. It wouldnt restart. I tested the coil with an ohm meter and it looked to be ok. I went and bought a spark tester and was unable to get a spark (I grounded the spark tester). I disconnected the tach wire and there was still no spark. The took the tach out of the boat and its pegged.

Today I tried to jump the coil with a direct 12v lead from the battery. I also had the negative side of the coil grounded and still no spark.

The grey tach wire seemed to be grounded.. Is that right? Would a ground lead coming off the battery fry the coil?

Thanks for all your help!

Joe
Fort Lauderdale

 

[dubs283]

Re: Battery Ground Came off 454 Merc running offshore...

first off there is NO WAY a bottle of water should be able to knock the ground cable off a battery terminal

if that is really what happened then you should have been more diligent about the battery cable connections and cable condition

that being said, there is a very good troubleshooting guide in the OEM anual about no spark for a t-bolt ignition

links to download a manual are in the must have info sticky at the top of the threads page

 

[BajabossJD]

Re: Battery Ground Came off 454 Merc running offshore...

Well it was a bag full of stuff. It was a terrible day on the water.. and I was working non stop to get the boat on the water. I must have left the cable loose. I am being honest.

I will check out the manual section.. I have used the diagnostic chart and everything is pointing to a bad coil..but unsure since the ohm test was ok.

Thanks,

Joe

 

[dubs283]

Re: Battery Ground Came off 454 Merc running offshore...

the troubleshooting guide will lead eventually to either a bad coil or module and states that you replace one and if no success then the other is the culprit

there is a way to test the module without just replacing it, but you need a digital volt meter to test it

 

[Bt Doctur]

Re: Battery Ground Came off 454 Merc running offshore...

"Today I tried to jump the coil with a direct 12v lead from the battery. I also had the negative side of the coil grounded and still no spark."

There is no ground on the negative side of the coil.purple and grey wires go to the amplifier. the other set that comes from the harness is purple (+12V ) and grey.(tach lead). by losing the negative lead completely, the alt runs wild and may have cooked all the electronic components

 

[BajabossJD]

Re: Battery Ground Came off 454 Merc running offshore...

I am hoping its just the coil. I did connect the 12+ direct from the battery to the coil and still did not see a spark. Is that the correct way to test the coil? I see all gauges (except) tach move when trying to start... I did the white/red wire test from the TBIV and I had 12volts.. I understand the purple wires, but I am not sure about the amplifier wires.. Is the amplifier the ignition on the port riser? I have a grey wire on the neg side along with a dark yellow..tannish wire. Both wires were there when boat was running great. For the tach to peg (probably ruined) .. would that mean that it was grounded out, shorting the coil?

Thanks for all your help guys,

Joe