Ignition fuse keeps blowing

[alexvelarde]

Please help! My Ignition Fuse Keeps Blowing
I have a 2006 Bayliner with a Mercruiser 5.0L (Serial # 0W622338)

Yesterday Boat seem to be running ok until it lost all power while going 20mph
I found out the 15amp Ignition Fuse Was blown. Tried to start the boat with new fuse and it would blow the fuse immediately.

About 4 hours later I started it and it was fine for 20 minutes until it lost power and shut off. I tried starting it again and it kept blowing the fuses.

I believe I had the same issue last year and the Ignition coil was replaced and boat ran good rest of the year.


Any suggestions would be greatly appreciated!

 

[Bt Doctur]

the fuse it listed as 20A not 15A. Is anything else hooked up to the wiring that didnt come from the factory?

 

[StarTed]

It sounds to me that you have something that shorts out when it heats up. Look at wiring and components in the engine compartment that could be affected by heat.

 

[alexvelarde]

No Title

For the ignition switch it calls for a 15A fuse (see pic below) I will look at the wires in the engine. What components should I look for? Could the ignition coil have gone bad again? Thank you for your help!

 

[Fun Times]

Check your purple and red/purple wires really close off the back of the alternator...Also be sure to inspect the orange wire too for wire chafing.

This member had the same issue as you and he found his problem...He even shows photos of the damaged wires at the end of the topic.
http://forums.iboats.com/forum/engin...e-s-n-ow635564

Mercruiser service bulletin number 06-02 - orange Alternator Wire.

Possible Chafing of Orange Alternator Wire on 5.0L/5.7L/6.2L MPI Engines.
Situation
On the units identified above, an orange wire attached to the output terminal of the
alternator (the orange alternator wire) was routed by MerCruiser in one of two ways. One
way was correct, the other was incorrect.
The incorrect routing places the orange alternator wire between the oil dipstick tube and
the alternator. With that incorrect routing, it is possible that the insulating material will be
chafed by the dipstick tube or the alternator, which could cause the wire to fail. If the wire
fails, it could become an ignition source. See the "incorrect routing" photographs below.
The correct routing passes the orange alternator wire beneath the alternator, not in contact
with the dipstick tube, which eliminates the opportunity for chafing and failure identified
above. See the "correct routing" photograph following.
In addition to the two orange wire routings described above, many boatbuilders modify or
disconnect the orange wire to facilitate the installation of battery isolators. Boats that have
been so modified will not require the corrective action outlined below.

Usually the orange wire may blow the 90 amp fuse on the engine starter and possibly damage a diode for the Turn Key Start system.

Not exactly sure why they changed that fuse to 15 amp when it was always a 20 amp. But somewhere around 2005ish they seemed to have gone to 15 amps vs 20.

Also your 2006 engine may not have the/a hidden 15 amp fuse but in your searches of the engine, you may as well double check to see if you have a hard to find fuse holder such as this guy had to find on his boat made in 2008.... http://forums.iboats.com/forum/engi...-3-tahoe-q4-please-help?p=5866601#post5866601

 

[bruceb58]

Ignition coils seldom go bad. Probably wasn't bad before.

Look for any wires rubbing up against your exhaust. Have you ever overheated your engine?

 

[ihc1470]

Go up on You Tube and look for short circuit detector or finding a active short. That should give you some good information to test with. Basically you are using a flasher and a compass to find where your issue is. This system works quite well. Do not move the harness's any if you can help it until you find your issue.

 

[Bt Doctur]

is this a throttle body fuel injected motor?

 

[alexvelarde]

No Title

So Fun Times, you may have been right. I checked the purple and red/purple wires off the back of the alternator and look what I found (see pic). Do you think this is my problem? (specially when the engine gets hot? ) How do I test this wire? Also there was a 20a fuse blown on top of the engine (is this a TKS fuse?) BT Doctur - my engine is not fuel injected

 

[Fun Times]

is this a throttle body fuel injected motor?

It's a carbureted engine,,, Service Literature for MERCRUISER 5.0L ALPHA 5.0L ALPHA

 

[Bt Doctur]

the red/ purple stripe could be the excite lead. that has power with the key "on" ground that and you will blow an ign fuse
Had to ask because I had one customer with blown fuses .Turned out to be the wires for the injectors crushed under the metal flame arrestor

 

[Fun Times]

So Fun Times, you may have been right. I checked the purple and red/purple wires off the back of the alternator and look what I found (see pic). Do you think this is my problem? How do I test this wire? Also there was a 20a fuse blown on top of the engine (is this a TKS fuse?) BT Doctur - my engine is not fuel injected

Looks like you found your problem.:encouragement:

Do you have a photo of the 20 amp fuse overall location?

Here's a few wire repair tips for you if needed,
https://www.youtube.com/watch?v=6EiIDNEiB_U
http://www.bing.com/search?q=how+to+...wire&FORM=AWRE

 

[alexvelarde]

No Title

Here's a couple of pic where the 20a fuse is located

 

[Fun Times]

Yes that is the 20 amp fuse for the TKS module system.

Bear in mind that there is a small chance that the TKS diode could have been compromised too. If that happens the engine may not turn off using the key or the engine may become harder to start when warm. TKS (Turn Key Start) carburetors. When the engine is ?

If the engine ever becomes to the point to where it won't turn off with the key switch, either you'll have to pull that fuse or try removing the Red diode which looks to behind the fuse/carb area in your photo.

 

[alexvelarde]

I plugged the waterhose to the engine and ran the motor for 30 minutes and it did not blow any fuse
It did have a little bit of a hard time shutting off.