Electrical/Ignition problems

T

ttommy2x4

Cadet
Joined
May 27, 2009
Messages
8
I have a Mercruiser 5.0 L V8 I/O in 21' Marada Cuddy cabin.

I took her out on the lake today. Started fine and cruised around for a while. Took a break and shut her down. Went to restart it and had nothing. I know it's not the battery. had a spare. I was able to bridge the bolts right at the starter and it would start but only if the key was held all the way right like you were cranking it from the ignition. As soon as I let the key roll back to just the on position the engine would shut down. Tried again and held the key all the way right again just hoping to limp her back to the dock but as soon as I put it in gear to try and move the engine would shut down. I checked the fuses and only found one blown fuse...not sure what it was for but I switched it out with the spare I had which was for the marine radio I didn't have hooked up. Tried again and still nothing when turning the ignition. I didn't even get the beep noise you should get when you just flip the ignition to the on position. I'm not sure what the problem could be. Any suggestions or ideas??
 
flargin

flargin

Chief Petty Officer
Joined
Aug 13, 2008
Messages
540
Re: Electrical/Ignition problems

it sounds like the switch may have gone bad.

essentially the "On" position charges the purple line which supplies 12v to the ignition coil, and other accessories.

when you go to "start" it is a momentary switch which supplies 12v to the starter through a relay (called a starter solenoid)

I don't know how much you know about electricity you are, but you can look (or post a picture if needed) at the back of your switch, check the lugs, there will be 3.

one will be battery in. 12V all the time. this is the Battery(B) (normally Red or Red/purple
one will get 12V when you turn the switch to "on", this is the Ignition (I) normally purple
one will get 12V when you turn the switch to "Start", this is the starting circuit (S) normally Yellow/Red


Another thing you may find is there is a 'lanyard' switch, which protects you/ your boat when you get thrown from the drivers seat, if this switch goes out, you could have similar problems.
 
T

ttommy2x4

Cadet
Joined
May 27, 2009
Messages
8
Re: Electrical/Ignition problems

I can't the pics to upload...file size is too big. I have a 3 switch ignition. Orange is the hot wire connected to the fuse panel. There is a purple going into a black plastic case of some sort then splits off and heads to the kill switch it looks like. Then theres the yellow and blue for the solenoid connection. I checked all the grounds on the fuse panel and all are tight..exercised them a bit in case of corrosion. Also checked my grounds back at the battery and engine. Still nothing. I'm not sure it's the ignition switch itself as I tried to take the wires off the back of the ignition switch to "hotwire" it and got nothing. Could it be a bad killswitch or a shorted wire somewhere?
 
flargin

flargin

Chief Petty Officer
Joined
Aug 13, 2008
Messages
540
Re: Electrical/Ignition problems

Take your meter, connect it to the battery negative post.

With key off/removed check:
Battery (Orange) should have 12 V
Ignition (Purple) should have 0 v
Starer (yellow/blue) should have 0v

With key in on position
Battery (orange) should have 12 v
Ignition (purple) shoudl have 12 v
Starter (y/b) should have 0 v
Both sides of the killswitch should have 12V
Purple wire connected to the ignition coil should have 12v


With Key in start position (might not need this but here for completeness)
Battery (orange) should have 12v
Ignition (purple) should have 12v
Starter (y/b) should have 12 v

See how that goes.

If you find one side of killswitch has 0, the problem is the killswitch
if the purple wire has 0, the problem is your ignition
if the purple at the coil is 0, the problem might be your boat to motor connector.

otherwise report what you find and we will try next steps.
 
T

ttommy2x4

Cadet
Joined
May 27, 2009
Messages
8
Re: Electrical/Ignition problems

Thank you so much Flargin...I'll give that a shot and let you know how it goes.
 
T

ttommy2x4

Cadet
Joined
May 27, 2009
Messages
8
Re: Electrical/Ignition problems

OK, got a voltmeter and did a few checks at lunch. Put the neg term of the meter at the ground on the fuse panel....I'm getting 12V at the fuse going to the ignition. I go to the ignition switch itself and touch the ORANGE wire connection and getting 4V so it seems the short or problem is with the wire going from the fuse panel to the ignition itself? Does that make sense? I didn't have time at lunch to actually pull the wire and inspect it.
 
flargin

flargin

Chief Petty Officer
Joined
Aug 13, 2008
Messages
540
Re: Electrical/Ignition problems

ttommy2x4 said:
OK, got a voltmeter and did a few checks at lunch. Put the neg term of the meter at the ground on the fuse panel....I'm getting 12V at the fuse going to the ignition. I go to the ignition switch itself and touch the ORANGE wire connection and getting 4V so it seems the short or problem is with the wire going from the fuse panel to the ignition itself? Does that make sense? I didn't have time at lunch to actually pull the wire and inspect it.
Click to expand...

Yes, that looks like a problem, because that will feed the coil, and that is not enough to run your boat.
 
T

ttommy2x4

Cadet
Joined
May 27, 2009
Messages
8
Re: Electrical/Ignition problems

I FOUND THE PROBLEM!!!

Took the fuse panel completely off and cleaned all the terminals and connections. Re-installed it and everything works now!!

I just wanted to say thank you so much for all the help and advice. I'm new to working on the boat all by myself as there's no boat mechanics close by where I love now....This forum has done wonders for me...I can usually find what I need without having to post but I really appreciate the response help with this one.
 
You must log in or register to reply here.
Top