No spark

[97_Manta_Ray_CR]

Hello all

I have a 18' how rider with a mercuiser 3.0 and an alpha one drive. I had an issue last weekend with no power to the engine and discovered it was the fuse under the dash replaced it and got the motor started yesterday ran the boat for about 20 min in tthe driveway with he muffs. Shut the motor down and then went to the lake in the process of trying to start the boat in the water it would just turn over and not start, come to find out after getting back home I have no spark. I think I have a short somwhere cause the boat will start of I put a constant hot to the coil pack from the battery. I'm not getting a hot from the purple wire to the coil pack from the alternator is there a way to test the alternator? I've taken the Alternator to all e big name auto part stores and they can not test it due to there limitaions, I also noticed that the fuse that I replaced is getting extremely hot.

Thank you for any help and advice

 

[Scott Danforth]

the purple wire supplies voltage to the alternator ignition terminal to excite the alternator. unless your motor is running, your alternator has nothing to do with your problems.

the purple wire is the ignition wire. it is the wire that goes from the ignition switch to the safety lanyard, thru 2-3 harness connections, then branches off on the motor to the coil, electric choke, and the alternator ignition terminal. if you do not have voltage on that wire, you need to back trace it backwards to the ignition switch to see where you are loosing voltage. when you get a no start, are your gauges live, or are they dead? if the gages are live, your issue is after the ignition switch. if the gages are also dead, it is your ignition switch.

prior to the ignition switch, the wire will be red (indicating battery hot). the wiring color codes are SAE standard.

 

[97_Manta_Ray_CR]

My gages are live, ant suggestion of why my hot wire with the fuse is so hot?

 

[alldodge]

Need to know the serial number or at least the year.

So if you run a hot wire to the positive side of the coil the motor starts, correct?
There is no power to the purple wire?

The fuse should not be getting hot (20 amp), what size fuse did you replace it with?

Testing the ALT is easy enough with the motor running. For now keep the two small wires on the ALT disconnected. This will take the ALT out of the circuit

 

[97_Manta_Ray_CR]

Its a 96, I'm thinking I have an issue at the kill switch can I bypass it and see if it starts?

 

[97_Manta_Ray_CR]

There was a 30a in there that blew so I replaced with another 30a

 

[alldodge]

Its a 96, I'm thinking I have an issue at the kill switch can I bypass it and see if it starts?

Yes, you can bypass the switch.

There was a 30a in there that blew so I replaced with another 30a

The fuse should be 20 amp. To keep a 30 amp installed something is going to melt and maybe catch fire. Need to find out what is drawing that much current.

 

[alldodge]

To find what is drawing all the current suggest, disconnect the coil, also the two small wires on the alternator. If you have any gauge which is not working, remove the purple wire off them. Need to get it to where a 20 amp fuse will not blow when installed and key turned on.

 

[97_Manta_Ray_CR]

Boat is running... I bypassed the kill switch...