Electrical short 4.3 Mercruiser 06Tahoe

[tlmoore62]

I have a 15 amp fuse that keeps blowing back by the distributor. This causes me to loose all power and kills the motor. Progressively got worse and now blows as soon as I turn the key on. Any help appreciated!!!

 

[alldodge]

When asking a question always best to provide the motor serial number, this way we know what your working on

The 15 amp fuse should be 12V main power. Things that draw direct from the fuse are the main power relay (MPR), power control module (PCM), idle air control (IAC), and throttle position sensor (TPS)

Disconnect the IAC and TPS to see if fuse blows. If it doesn't, reconnect one at a time and try again.

 

[tlmoore62]

When asking a question always best to provide the motor serial number, this way we know what your working on

The 15 amp fuse should be 12V main power. Things that draw direct from the fuse are the main power relay (MPR), power control module (PCM), idle air control (IAC), and throttle position sensor (TPS)

Disconnect the IAC and TPS to see if fuse blows. If it doesn't, reconnect one at a time and try again.

Thanks so much for the reply, can you help me with locating where to disconnect TPS and/or IAC? Thanks

 

[alldodge]

Thanks so much for the reply, can you help me with locating where to disconnect TPS and/or IAC? Thanks

The TPS is on the throttle body (TB), the IAC is either on the TB or the intake

Again, I need a serial number

 

[tlmoore62]

S/N A063297 2007 Family 7M9XM04.32VC

 

[alldodge]

Thanks
You don't have a IAC or TPS, you have TKS carb.
Normally when the fuse blows it just keeps the carb running rich, but it does keep running. For it to start killing the motor I would look at the temp switch and the TKS module

Verify you have a carb that looks like this

 

[tlmoore62]

Thanks
You don't have a IAC or TPS, you have TKS carb.
Normally when the fuse blows it just keeps the carb running rich, but it does keep running. For it to start killing the motor I would look at the temp switch and the TKS module

Verify you have a carb that looks like this

View attachment 326900

 

[tlmoore62]

this looks correct, when the fuse blows, it will not crank, no power to anything until I replace it.

 

[alldodge]

The TKS has 2 power feeds which can power the ignition. The TKS fuse and the 20 amp fuse from the key switch (not shown in pic)
This is a simplified pic

 

[tlmoore62]

Im sure of what fuse is blowing, but not clear on where to start with finding the short causing it to blow. Any direction on where to start? The 15 amp fuse back by the distributor I'm assuming must be the TKS fuse?

 

[alldodge]

Disconnect the temp switch (item 5) on the intake, this should keep the fuse from blowing. If ignition switch blows after temp is disconnected then disconnect the TKS carb

https://www.mercruiserparts.com/bam/subassembly/31493/12833/90

 

[Fun Times]

Over the years we've had some TKS fuses burn out and here are a few memorable ones that may help give some indications of where to look for some other general ideas,

Mercruiser 4.3 blown ignition fuse

2008 Searay 185 104 total engine time stored indoors original owner...ignition fuse (in forward fuse block) blown while cruising at 4400 rpm at end of a couple hours of tubing.. Engine just died...left instrument panel radio etc without power. Tried new fuses that blew immediately when key...

forums.iboats.com

Mercruiser 4.3 TKS -- Blown Ignition Fuse and Shorted TKS Diode

I have a 2008 Sea Ray Sport 205 with a Mercruiser 4.3L TKS engine. Recently the ignition fuse blew and I discovered that the TKS diode was shorted. After I removed the diode and replaced the fuse, the engine started and appeared to run fine. I ordered a new diode thinking that this would resolve...

forums.iboats.com

But from the descriptions, and the boat model and engine combo, It sounds like maybe the 15 Amp fuse isn't part of the TKS system but more of what is sometimes called the Clean Power System coming off of the 10 pin cannon plug area and this fuse is considered hard to find do to location.

To know if this may be the case, please have a look at this post with photos to see if this may be what you're after and where you found the blown fuse...If so then there have been roughly 3ish other types of similar issues over the years since this thread was made.
#65 = https://forums.iboats.com/threads/hidden-fuse-on-4-3-tahoe-q4-please-help.536975/post-3863038

 

[tlmoore62]

Over the years we've had some TKS fuses burn out and here are a few memorable ones that may help give some indications of where to look for some other general ideas,

Mercruiser 4.3 blown ignition fuse

2008 Searay 185 104 total engine time stored indoors original owner...ignition fuse (in forward fuse block) blown while cruising at 4400 rpm at end of a couple hours of tubing.. Engine just died...left instrument panel radio etc without power. Tried new fuses that blew immediately when key...

forums.iboats.com

Mercruiser 4.3 TKS -- Blown Ignition Fuse and Shorted TKS Diode

I have a 2008 Sea Ray Sport 205 with a Mercruiser 4.3L TKS engine. Recently the ignition fuse blew and I discovered that the TKS diode was shorted. After I removed the diode and replaced the fuse, the engine started and appeared to run fine. I ordered a new diode thinking that this would resolve...

forums.iboats.com

But from the descriptions, and the boat model and engine combo, It sounds like maybe the 15 Amp fuse isn't part of the TKS system but more of what is sometimes called the Clean Power System coming off of the 10 pin cannon plug area and this fuse is considered hard to find do to location.

To know if this may be the case, please have a look at this post with photos to see if this may be what you're after and where you found the blown fuse...If so then there have been roughly 3ish other types of similar issues over the years since this thread was made.
#65 = https://forums.iboats.com/threads/hidden-fuse-on-4-3-tahoe-q4-please-help.536975/post-3863038

That is the fuse that I am having the problem with. It took me a half day to find it, once I replaced it, it fixed the problem for a few weeks, then blew again. I think I found the issue, a couple years ago when I took the boat in to be winterized, the mechanic said he couldn't keep it running and had to jump a wire around the main harness connection. I found that the jumper wire connection he installed came apart and was shorting on the block. I took the harness connection apart, cleaned the pins, spread them a bit and reconnected. Everything seems to be working fine now. Thanks for all the help and direction, these electrical problems eat my lunch!!!

 

[alldodge]

What color are the wires going to the fuse?

 

[Fun Times]

Glad you found it and was able to solve the problem.

I'll add that if you happen to use an bigger amperage draw device such as an Air pump for a inner tube, etc., and use 12v power from the helm area such as a cigarette lighter adapter with plug design then it's been known that a 15 Amp fuse there may be to small and blow often and going up to a 20 generally helps stops blowing the fuse right away....But be extra cautious feeling for heat to the wires and try not to run it continuously.