blowing 15A. ignition fuse

[k_burg]

I have a 99 bayliner 2655, I just changed the 5.0 to a 5.7 mercruiser carb. thunderbolt IV ignition over the winter. It motor runs fine but once up on plane running around 3800rpm for a few min. the 15a. ignition fuse blows, all gauges go dead and motor shuts off. Change the fuse and starts right back up. I can run the boat all day at 2000rpm with no problems. I have changes the cap, rotor, plugs, wires and coil. I have messed with the wire harness under the dash while running and cannot get the fuse to blow. Just recently thou I have had trouble starting the engine when cold, not sure if its related.I think the electric fuel pump is original. The altenator was run on old motor and changed middle of last year, starter is new and cranks great. I had even put a 25A. fuse in that position because I ran out of fuses and just needed to get back to the dock but it blew that also, so it a heck of a current draw. Any thoughts?????

 

[Bondo]

Re: blowing 15A. ignition fuse

so it a heck of a current draw. Any thoughts?????

Ayuh,... Probably a Dead Short, ya just gotta Find it....

 

[k_burg]

Re: blowing 15A. ignition fuse

but wouldn't a dead short blow the fuse as soon as the key was turned on?

 

[fossill]

Re: blowing 15A. ignition fuse

Check your wiring in the engine compartment. I'd bet that at the higher rpm vibrations are causing a wire to flex or wiggle against something causing the dead short.

 

[k_burg]

Re: blowing 15A. ignition fuse

I will have to take another good look around. Is the fuel pump on the ignition circuit, because I know it doesnt come on till oil pressure builds up. Is it possible that the pump could heats up under high demand and cause high resistance in the system?

 

[mivers1]

Re: blowing 15A. ignition fuse

I have a '99 Bayliner with a 3.0L Mercury and it has the same problem. I replaced the 15A fuse with a 30A fuse and it has not blown yet (but for obvious reasons I'm trying to figure out how to actually correct the problem before going back out.)

 

[mivers1]

Re: blowing 15A. ignition fuse

The 30a fuse was chosen since the online fuse to the fuse panel on that model is also 30a. Additional info: I bought the boat used and the gas it may not be old. I do know the engine was running rough and that the plugs seemed to be in good shape. The engine appears to have very little wear and I was told that the boat had less than 100 hours on it. (The engine compartment seems to reflect that this is a valid guess, however, with enough work you can clean anything I suppose.)

 

[Eric 3.7LX Alpha 1]

Re: blowing 15A. ignition fuse

I have a '99 Bayliner with a 3.0L Mercury and it has the same problem. I replaced the 15A fuse with a 30A fuse and it has not blown yet (but for obvious reasons I'm trying to figure out how to actually correct the problem before going back out.)

Yeah definately don't wanna keep that 30 in there, the fuses protect the wiring and electrical equipment, which will become damaged if the amperage goes over what they are rated for.

Best guess would be to get a manual and wiring diagram try figure out what color wires are on that circuit and trace everything looking for where it might be shorting to a ground.

 

[ACOOK]

Re: blowing 15A. ignition fuse

I am original owner of 1997 mercruiser 3.0 l on a bayliner.
I get no current to engine, guages, lights, trim, etc.
Battery is new & properly connected.
A dealer told me there is a square fuse attached to front of starter.
Sorry, there is no fuse in that position.
Where else can i look for such a fuse?
Can it be a 15a blade fuse somewhere?
Any guidance will be appreciated.

 

[Bondo]

Re: blowing 15A. ignition fuse

I am original owner of 1997 mercruiser 3.0 l on a bayliner.
I get no current to engine, guages, lights, trim, etc.
Battery is new & properly connected.
A dealer told me there is a square fuse attached to front of starter.
Sorry, there is no fuse in that position.
Where else can i look for such a fuse?
Can it be a 15a blade fuse somewhere?
Any guidance will be appreciated.

Ayuh,.... Welcome Aboard,...

Start yer Own thread, insteada Hy-jackin' this ole Antique....