Reversed battery polarity

[rjva]

Well, I was in a hurry to get my boat ready for the spring and hooked the battery up BACKWARDS!!!! There was a spark and thats that. No gauges, engine wont crank, nothing. I get horn, bulge, blower, but, nothing else. Found two inline fuses comming from the battery, a 60amp autombile type fuse and a 24V terminal type fuse. Checked the main engine circut breaker, its just a red button, pressed it and am assuming thats all you need to do. Any help would be appreciated...

[rjva]

Sorry forgot the important details...

20i, 2001 with a 350 MPI....

[FKM]

how many wires are connected to your battery? There should be (if i recall), 2 large cables on the +, and 2 large cables on the -, along with a bilge pump wire.

Also, did you check the fuse panel under the dash?

Sparks are normal when you hook up a battery if a switch is left on. Most of the dumb equipment (blower, bilge pump, lights, etc) wont care which way they are hooked up, but the computer on the motor is a different story. IF you still cant get it to crank, take it to a dealer, might have fried the ECU.

[raythompson]

Might not be ECU

Originally posted by FKM
IF you still cant get it to crank, take it to a dealer, might have fried the ECU.

It should be able to crank without the ECU, it just will not start. The starter is simply a selenoid that should not be polarity sensitive. I would suspect more a fuse or inline circuit breaker that has tripped. I know that on a car the ECU is polarity protected, don't know about marine use.

But, engines being what they are and becoming more complicated, perhaps the starter selenoid is somehow tied into the computer and without a signal will not engage the starter. So I could be wrong.

Reset the breakers, find the fuses and circuit breakers, make sure they are OK. Then try and start the boat in the yard (with appropriate water supply) before going to the ramp.

You might be lucky.

Oh, and you have my sympathy. I know that sick feeling in the stomach. Had that when I beached my old boat, happily went about my events, and several hours later discovered the boat half sunk because I forgot the drain plug. Water was halfway up the engine and destroyed the starter and alternator. Not to mention digging under the boat to get the plug and getting all the water out. The bilge pump did surprisingly well even though it took over an hour to pump all the water out. A lesson painfully learned.

[lee]

Check the 90 amp fuse that is on the end of the red battery cable that is connected to the starter.

[Jeff LaHaye]

Lee is right - 90A fuse on starter

Been there, done that!

2001 2100V Ltd with same 350 MPI engine.

Follow the power cable into the starter, the 90A fuse is right at the connection terminal. It's not obvious it's a fuse, looks more like the terminal block itself. If you have your Merc manual, there should be a good diagram. Any Merc dealer should have the part.

Good Luck!

Jeff

[rjva]

I found the 90amp fuse on the starter and checked continuity. It seems ok? Could it still be bad? Maybe Ill remove the fuse and test? Even if that fuse was bad would that cause the gauge panel/wakeboard pro to be completly dead? Sorry for so many questions, I live on a small lake and the closest Tige dealer is several hours away. I am on my own. I am praying its not the ECM, those things are expensive. Thanks again for all your input.

[Jeff LaHaye]

rjva,

I'm sure you have other current paths through the electrical system that would show the fuse as having continuity if you haven't pulled it off.
I'd definitely remove it and test it again.

If it's indeed the fuse, you don't need a Tige' dealer. Any dealer/marina that supports Merc should have the part you need.

When I had the problem, I had a dead battery and was jump-starting from another battery. I accidently reversed the polarity on the extra battery, sparks flew and everything went dead.

My memory is that everything electrical on the boat was dead, as if the battery switch had been turned to off. It's been a couple of years, so I might be fuzzy as to whether I had some power on auxilary systems...

I was pretty scared, really thought I'd fried something serious.

After a few hours of probing around, I got out my Mercury manual that came with the boat and the trouble-shooting guide directed me to the 90A fuse.

I was able to jump on my SeaDoo and run over to the podunk Marina on the lake that services and stocks Merc, and they had a fuse. I threw the guy a $20 and thanked him for saving my weekend.
I got the fuse installed and everything has been fine ever since.
I just won't repeat that mistake again!

Good Luck.

Jeff

[raythompson]

The only thing scarier

is dropping an box end wrench and having it short across the battery terminals. The wrench welded itself to the terminals and could not be removed. The wrench melted on the box end where it was thinnest and made contact. And of course warped the plates in the battery from the current draw and I guessing the heat. The battery was toast. This was a large 6 volt battery used in a piece of farm equipment. The battery weighed about 45 pounds and was quite large.

I asked a knowledgeable person how much current went through the wrench. He responded with a sheepish grin on his face "All of it."

Now I not only disconnect the batteries, but cover the positive terminal with a couple of layers of electrical tape.

[rjva]

Thanks guys, I ordered the 90 amp fuse. I will continue to sweat until it arives. I'll let you know the outcome....

[rjva]

The 90 amp fuse was the problem..

Thanks Gentlemen, the fuse did the trick. Thanks again, I should be in the water next week!!!

[Tige M.D.]

did you get an extra fuse? you never know when your gonna need another one

[raythompson]

Re: The 90 amp fuse was the problem..

Originally posted by rjva
Thanks Gentlemen, the fuse did the trick. Thanks again, I should be in the water next week!!!

That is good news.

At least it wasn't a $400 computer protecting a $4 fuse. Yours failed in the correct order.

[Jeff LaHaye]

Good to know the system is well designed!

That's great news!

I agree with Ray's comments - the right part failed!

Jeff

[lee]

Chalk one up to the JR Member!