Ignition wiring questions.

[woodguy81]

I’ve got a bay liner trophy from 1998 with the 5.0 mercruiser engine and alpha one drive. Just getting it going for the season and nothing at the key. Battery is tested and good. The kill switch seems to be good. I attempted to jump it and leave it disconnected since I didn’t know if it was a normally open or closed circuit. Testing gets me 3 volts on the red wire with the purple stripe. Nothing at the other 2. The power blocks behind the dash show 12 volts. Any idea where to look or why it would read so low?

 

[woodguy81]

Also got 3 volts at the breaker on the engine and at the alternator power post.

 

[woodguy81]

Update. Disconnected the “new” alternator and now I get 12 volts but still nothing when I turn the key.

 

[alldodge]

You have a bad connection
Remove the battery cables at both ends which includes the negative on the engine block. Clean them up to nice shinny metal

 

[woodguy81]

No change

 

[alldodge]

Connect the volt meter to the starter post, then turn key to start. What is the reading?

If voltage stays the same then try same at the 50 amp breaker, both side one at a time

If no change try at the key switch

 

[woodguy81]

Voltage at the key goes to 0 when I turn it. I gotta check the other 2

 

[woodguy81]

Ok. So now I’m at the 90 amp fuse. Pulled it off bc it was terribly corroded. Took it in the shop and cleaned it and tested it. No continuity. How could I have had voltage to the wires above it if it’s not showing any continuity. Any thoughts. I’m of course going to replace it before doing any additional troubleshooting.

 

[alldodge]

Don't know how you would get a reading without actually seeing and testing the wiring. Might have just been rust allowing voltage to transfer, but would do nothing when current draw increased

 

[woodguy81]

I was testing for voltage above the fuse. Didn’t realize it was even down there. Had voltage at the alternator post and the breaker on top of the motor. Both the wires that come from the fuse. There is no continuity through the fuse now that I’ve got it off the starter. That’s why I’m confused.

 

[alldodge]

The 90 amp fuse block, has a 90 fuse inside it
The glass fuse is inside the block

 

[woodguy81]

This is what came out of mine. No glass but the rest looks the same. Came out in corroded pieces.

 

[alldodge]

The fuse isn't glass its clear plastic. The fuse is the top right in the pic

 

[woodguy81]

Appreciate the help. I’ll get this replaced and let you know if that was this issue.

 

[nola mike]

The fuse isn't glass its clear plastic. The fuse is the top right in the pic

When I bought a new replacement there was no clear plastic inside. It was just a metal link isolating the 2 lugs fwiw.

 

[alldodge]

Can still get them, look for bussman, but a fuse for the most part is a fuse
https://www.amazon.com/Blue-Sea-Systems-MRBF-Terminal/dp/B0016HX6HA

 

[woodguy81]

Fuse fixed it. Thanks for the help.