Logo
FULL SITE MENU

2000 Mercruiser 4.3L electrical problems driving me crazy...help.

L

Lou23

New member
I apologize ahead of time for a long post. I have a 2000 deck boat with a Mercruiser 4.3 that has had a lot of electrical problems. Last year I replaced the starter slave solenoid, both trim solenoids, the distributor pickup coil and the ignition coil. Also new bilge pumps. Towards the end of last year my battery kept going dead if the boat sat. This year I still have the battery issue. It will go dead overnight. I checked for amp drain with the key off and came up with about 0.2 amp drain. Started taking dash apart and found a melted ground wire jumper from fuel gauge (was not working) to the main ground cable on the tachometer. Also found a melted section of ground wire closer to the connector and a suspect pin. Repaired the bad grounds and rechecked, amp draw now down to 0.02 amps. Ran boat with muffs and all seemed good, everything worked. Since then I have installed a battery switch to disconnect and/or run 2 batteries. Also replaced the battery as I thought possibly it was just a bad battery. Ran boat on the lake for 2 hours, ran great and everything worked as it should. Shut it down and left it overnight, battery was down to like 5 volts by morning. I have had conversations with a couple of people trying to help over the phone and internet. Last suggestion was to disconnect the alternator. I charged the battery, disconnected the alternator, but won’t be able to check until later this week. Thought I would see if anyone has had any similar problems, or suggestions. Any help appreciated. Thanks
 
Bt Doctur said:
click to enlarge
Click to expand...
Sorry, I did install it correctly and the battery has no drain when switch is off. My problem is keeping power to the bilge pumps. There are 2 bilge pumps connected to a water witch sensor and also 2 switches on dash that allow manual/automatic settings. My original setup was to run a fused hot wire off the battery and connect it to the positive lead of the Water Witch. Thought was that this would allow bilge to be live even though all other positive cables are disconnected by the switch. With that setup the battery still discharged overnight. Not sure if the power to the sensor somehow back fed the dash and caused a drain. I could also run a float switch and one of the bilge pumps completely independent of the boat wiring but it still doesn’t solve my problem. I see it more as a bandaid and I would like to figure out why the battery drains so quickly. Thanks
 
Re: "Sorry, I did install it correctly and the battery has no drain when switch is off.".... and if this is true, the alternator could not drain the battery.

Not a fan of other than caged float switches. Electronic ones draw power ALL the time... usually a very small amount, however, high/higher than normal current draw at inopportune times is a failure mode with electronic devices.

re: ... "...Not sure if the power to the sensor somehow back fed the dash and caused a drain..." NO, excess drain of the water which will directly drain the battery, feed back to the dash is irrelevant..... unless there is also wiring from the bilge pump to an on/off bilge pump switch on the dashboard as well???
 
There are 2 switches on the dash, one for each bilge pump. They have 2 settings, either Manual or Auto. I verified that the Water Witch works with the key off. After I put in the battery switch (Blue Sea dual circuit plus 6011) I ran a separate fused positive feed to the red power lead of the Water Witch. There was already a connection from the dash to the sensor so I just added another feed. All 3 connected.
 
I want to verify I’m checking this correctly. I pulled all 3 negative cables off of battery. First I ran the meter between the main negative cable and the battery post and got zero amps. I connected that cable to the battery and then ran the meter between each of the remaining 2 ground cables and the battery post. Slight differences at times but basically 0.02 amp draw from the cable marked “Negative” with a green and black combined connection. When I add the second ground cable I get about 0.08 amp draw. So the total drain is about 0.08 amps. Problem is the battery will drop to about 7 volts within a couple of hours.
 
Back
Top