91 7.4L Complete Failure

[BigTom77]

I recently purchased a 91 Wellcraft 250 Eclipse with a Mercruiser 7.4L engine. The boat starts and runs great but about a mile down the river the engine and whole electrical system die instantly and I'm dead in the water. I have absolutely nothing. No starter, guages, blowers, pumps, etc. After a while of floating I will regain guages and some electrical stuff and a bit later the engine will start and run fine again for a while and then the same thing happens. I would really love some help with this issue before a barge runs me over. Thanks!

 

[Don S]

Re: 91 7.4L Complete Failure

Sounds like you need to clean some battery terminals and TIGHTEN them. WIng nuts should NOT be used. get some regular nuts and tighten with a wrench.
Could also be the battery selector switch if you have one. or even loose cable ends on the battery cables either Positive or Negative cables. Check both ends of the cables.

 

[BigTom77]

Re: 91 7.4L Complete Failure

I installed a brand new batter yetsterday and the terminals are cleaned and bolted on. I have not checked the starter side of the cables but will do that today. Could lose battery/starter cable actually kill the complete system like that? I figured there was some kind of themal link or a protective breaker/ fuse of some sort tripping. Thanks.

 

[Don S]

Re: 91 7.4L Complete Failure

Could lose battery/starter cable actually kill the complete system like that?

Absolutely, and like I said check the ground cable too and they have 2 ends on each cable.

I figured there was some kind of themal link or a protective breaker/ fuse of some sort tripping.

There are no automatic reset breakers in the electrical system that covers everything, or at least there shouldn't be.

 

[BigTom77]

Re: 91 7.4L Complete Failure

Thanks for the help! I will tighten the cables and try the boat out today. With a bunch of luck the boat will run for me! I can't figure how loose cables would allow the boat to re-start after it cools down but I will give it a whirl and see what happens!! Thanks again

 

[Don S]

Re: 91 7.4L Complete Failure

I can't figure how loose cables would allow the boat to re-start after it cools down

A lot of people think that, until they tighten things up and it works.

Take a meter with you. if failes again, follow the power from the battery forward and see where you loose voltage.

 

[danond]

Re: 91 7.4L Complete Failure

Bigtom I just had a similar problem with mine. Might I suggest that you remove the cables and clean the connections. It won't be a waste of time.

 

[BigTom77]

Re: 91 7.4L Complete Failure

I'll clean all connections today and let you know what the outcome was later tonight. I would love it if it was something so simple!!! Thanks fellas!!

 

[BigTom77]

Re: 91 7.4L Complete Failure

Well fellas, I did as you said and I never had a problem today!! Of course my cousin "electrical engineer" was on the boat with all his toys to chase down the problem today when it happened. I guess that's the way it goes though! Thanks for the help!!