I could use a little help here!! 3.0 Mercruiser / Alpha One...

[jpx8080]

OK... Hello everyone,

Here is the issue: I have a Mercruiser 3.0 with an Alpha One outdrive on a 1998 Stingray 190RS. I can run WOT with out any issues but intermittently when I bring the throttle back to neutral I blow the 10A ignition fuse. I went through the whole adjustment for the shift cable and interrupt switch and all seemed well. (I thought that it was the problem initially but now I'm not so sure).

I was checking all of the wiring today and when I was looking through the schematics I noticed that the purple wire seems to be the main wire on the engine that keeps the boat running.

I also noticed that my purple wire was short to ground. Maybe this is why it is blowing the fuse? I started disconnecting everything that is connected to purple to try to isolate the ground and it seems that the only thing to disconnect the purple from ground is removing it from the electric choke.

Now I am not sure but is it normal for the purple to have a short reading to ground with the choke connected? I'm at a loss here. I only have 189 hours on the boat and this is the first real issue that I've had. I don't want to take it to a marina and pay for a bunch of experiments! I'm an electronics tech for the Coast Guard so I know my way around wiring if any of you would be able to help me figure out why this fuse is blowing...

Thanks in advance,

Paul

 

[Brew411]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

As you are an electronics tech I am probable stating the obvious here but sometime the simplest solution is right in front of you so I will go ahead. Of course a fuse will blow when the amperage flowing through it exceeds the amount of amperage the fuse is rated for. So, which part or component that the fused wire it is connected to has begun to operate differently that is causing it to use or draw more amperage current? Perhaps the electric choke? Sometimes when an electrical part is getting ready to meet its maker it will draw more amperage to make up for its own short coming until it finally goes Kuput!

 

[Brew411]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

Also Paul, Since it is a throttle assembly, with moving parts, did you look inside to check for chafing of the wires? A chafed wire would read grounded if indeed in intermittent contact with metal as you manipulate the throttle control arm.

 

[coheej]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

the choke will have low resistance until it heats up; probably under 10 ohms.
Be sure the range setting on you meter isn't set too high and making it look like a short.

 

[jpx8080]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

Thanks for all of the replies so far. I was looking at the shifter control itself (Quicksilver 3000 Classic) and I noticed that the wires were very tight and rubbing on metal. I cannot tell whether or not any insulation is missing yet because I am trying to get the handle open/off.

I hope this is the problem. Any more ideas are more than welcome.

Also, I'm going to count out the choke as of now after opening it up everything looks fine. I can't see any reason to assume that it's the problem.

 

[jpx8080]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

UPDATE: I went through the throttle and found not chaffed wires. I'm going to go out in a bit and buy a ton of wire loom and clean all of the wires on the motor and secure each and every one. Then I'm going to go through the shift interrupter switch adjustment one more time. I hope this works. I have a couple of days off and I'd like to do some fishing!

 

[jpx8080]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

Just another thought... Does anyone know if 10A is the correct fuse rating? I'm only asking because I've read a lot of similar problems online and a lot of people are stating higher amperage ratings on their ignition fuses. I've seen people online with fuses as high as 30 there. That seems like a lot to me but in all reality, I could be troubleshooting something that doesn't exist!

 

[Alpheus]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

Make sure that someone didn't hook your shift interrupt switch wrong. Make sure there is no chaffing on the green/white wire off the shift interrupt switch. If this happens every time you activate the switch it will cause a direct short to ground...

 

[rodbolt]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

typically the ign fuse is 20 amp.
look closely at the diagram or find the owners manual.

 

[Alpheus]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

Oh, I'm sorry. Here are some links to the manuals that could help...


http://www.4shared.com/document/Ou0ZU3_4/Mercruiser_Service_Manual_13_G.htm

http://www.4shared.com/document/D-qIfFRU/Mercruiser_Service_Manual_10_1.htm

 

[jpx8080]

Re: I could use a little help here!! 3.0 Mercruiser / Alpha One...

Thanks for the manuals.... The ignition fuses shown are all 20A. I'm thinking that my plan is going to be:

1. Finish cleaning every electrical connection and finish installing wire loom on all wires.

2. Re-do the shift cable adjustment and shift interrupt switch adjustment.

3. Put the boat in the water and leave it on the trailer and take some Amperage readings on the circuit while switching from in-gear to neutral.

4. Install the 20A fuse in the ignition #2 slot on the dash (which is what the service manual has installed).

I guess I'll know by this evening if it worked.

If any of you guys ever need help with anything on your boats, let me know. I appreciate all of the help on here.

I wish that someone on here had a merc 3.0 with an alpha one and could go look in their dash and tell me what is in the "ignition slot"!

I may have been troubleshooting nothing except for a "wrong size" fuse but I have learned a ton about my boat's electrical system and I am a pro at adjusting the shift cable and interrupt switch!

Thanks again!