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Instrument Panel (engine, ignition) fuse blowing

 
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MikeLTour61



Joined: 18 Apr 2010
Posts: 3

PostPosted: Sun Apr 18, 2010 4:01 pm    Post subject: Instrument Panel (engine, ignition) fuse blowing Reply with quote

There is a 20 amp fuse that is wired to terminal 'I' of the ignition switch of my 1987 Mercruiser Alpha-One 175 V-6 that keeps blowing. The first two times it blew, I was advancing the throttle past idle so I thought problem was in the shift cut-out switch area. I disconnected it and was able to keep the boat running so I reconnected the switch and the problem disappeared for the rest of the day.

Yesterday, I went out again and left the dock with no problem - the shift cut-out switch was connected. I was cruising along at about 3000 rpm when the engine just cut off. The fuse was blown again. I replaced the fuse, cranked up the engine and, after the engine idled for about 5 minutes, the fuse blew again. I replaced it AGAIN (getting ready to head back to the dock) and decided to give it another try. Everything worked fine for the rest of the day. It seems like it needs to burn up two or 3 fuses and then it's happy.

The boat is stored inside and is used in fresh water. The trim sender(s) are disconnected.

Has anyone seen a problem like this? Could I be looking at a distributor or ECU problem? I would think if one of those failed, it would be DEAD. Also, the gauges are original and don't look all that great. I know they work off the same fuse.

HELP.... Please!!
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MikeW
Senior Member


Joined: 01 May 2006
Posts: 680

PostPosted: Tue Apr 20, 2010 7:35 am    Post subject: Reply with quote

First thing to do is trace the wire to see if it is grounding out somewhere. If you can't find anything, run a temporary wire with an inline fuse and see if the problem goes away. Cool
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MikeLTour61



Joined: 18 Apr 2010
Posts: 3

PostPosted: Tue Apr 20, 2010 4:29 pm    Post subject: Reply with quote

I was going to try splitting the power - half to the instruments and half to the engine.
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fftpete



Joined: 08 Sep 2010
Posts: 2

PostPosted: Wed Sep 08, 2010 8:21 am    Post subject: Reply with quote

I'm having the same problem with a 98 Searay with a 4.3. I have had it at the local boat shop to the tune of 1,100 dollars and it still blows the ignition fuse. They replaced the gauges and checked for bad grounds. I fixed the grounds at the battery and have replaced the voltage regulator in the alternator and I still have the same problem. Tomorrow I'm going to replace the ignition module in the distributor and the coil. If that does't work then I am out of ideas. I was just wondering if you were able to get yours figured out. Thanks.
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MikeLTour61



Joined: 18 Apr 2010
Posts: 3

PostPosted: Wed Sep 08, 2010 3:56 pm    Post subject: Problem resolved Reply with quote

I finally figured out what the problem was. I'm glad I didn't have to pay someone to do it!

There is ONE fuse that protects and feeds power to all the instruments plus most of the components on the engine.

What I did first was split out the engine and dashboard electrical and installed smaller (10 A) in-line fuses for each side. Within an hour of running I had the answer: Something on the engine side was causing the main fuse to blow.

The next step was to install a fuse panel that split out the five components that the purple hot wire from the instrument panel fed. On the engine-side of the wiring harness connector, I unwrapped the electrical tape and found that there were splices that fed the alternator, fuel pump (via the oil pressure switch), electric choke, the ECM and something else that I can't remember at the moment.

I estimated the sizes of the five fuses that would feed each component... none of them > 15 amps so I'd still blow the fuse of the offending component before the main fuse. Then I started the engine and after about five minutes of idling, it seemed like the boat was running out of gas. After it petered out, I checked the fuel pump fuse and it was blown! I bench tested the fuel pump and it ran at about 3 amps for 5 minutes or so and then it maxed-out my 12 V power supply. I re-tested and got similar results.

I ordered a MARINE fuel pump from Summit and installed it and have been boating trouble-free since.

I hope this helps.
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fftpete



Joined: 08 Sep 2010
Posts: 2

PostPosted: Sun Sep 12, 2010 5:58 pm    Post subject: Reply with quote

Well today I put in the ignition module and the ignition coil and took it to the lake to test it. The fuse blew just like all the other times. I am going to order a fuel pump now and see if that works. This is just so frustrating because I haven't been able to use it all summer and now the season is almost over. ( I live in Iowa) I hope this works and I will post the outcome. Thanks for your advise.
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