I do not get any reading on my ammeter that the charging system is working on my 75hp Johnson. This has been that way every since I bought the boat, which has been about 7 years. Since I only get out a few times per year and the battery is always charged, it may not even matter that much.
However, I would like the advice of some of you seasoned (I didn't say old) OMC outboard mechanics regarding a couple things. I really don't want to follow the advice of my service manual and try to test sample spots with a voltmeter @ 3500 rpms... I would just like to check a few easy items first.
My ammeter usually shows a slight discharge. I haven't switched the leads yet. I believe I put them back the way the previous owner had them, so maybe they were not right in the first place. The discharge is maybe a needles width, so less that 5 amps.
This particular motor year was the first to use a generator kit. I thought I would check the fuses described in the service manual. There is an in-line 20 amp fuse which looks good... And then a reference to a 60 amp Charging Circuit Fuse..
In the fusebox, there is an arrow to Gen Fuse... but when I unscrewed the two screws and slid out the heat sink assembly, I didn't see anything that looked like a fuse.
Can anyone describe this fuse... is it a wired in fuse that looks like a capacitor or something? I was hoping to find something shaped like fuses for a house, with snap in and out capability.
Or is this even something that I should mess with at this point. My thoughts are, if I can fix it easily, I would try. But if I am going to start down a path of voltage regulators, and other diagnostics, I will probably just put the fusebox back together and just make sure the battery is fresh each time I go out. I am usually not out for more than 4 fours at a shot.
By the way, does the motor drain the battery as it is running, assuming no other load like lights/etc. is running. Or will the magneto keep the engine running without consuming energy from the battery? That way, I know that the only drain is when I engage the starter.
Any advice will be appreciated.
John.
Advice on charging system on 1961 Joohnson 75hp - Fuses
Moderators: a j r, TDockside, Miles, Moderators
OK the model having the alternator is V4A - 13 ( the magneto model is V4S-13) . The factory service manual has a quite extensive trouble shooting guide for the charging system. Many tests are with the engine off, some with the engine at a fast idle. One of the first things to look for in a "no charge" condition is a blown 60 amp charge circuit fuse... you are correct it dosen't look like a normal fuse.
Also... watch your amp meeter as you switch the key from "off" to " on" , if the meter is working you should see a discharge of 4 to 10 amps.
Another simple test to check for charging... connect a volt meter across your batery terminals ( 12 Volt) ... start the engine at fast idle you should read 13 -15 volts indicating that you are charging.
Do you have a factory service manual? Worthwhile to have! ... Ken Cook Co, not "cheap" about $50
Joe B
Also... watch your amp meeter as you switch the key from "off" to " on" , if the meter is working you should see a discharge of 4 to 10 amps.
Another simple test to check for charging... connect a volt meter across your batery terminals ( 12 Volt) ... start the engine at fast idle you should read 13 -15 volts indicating that you are charging.
Do you have a factory service manual? Worthwhile to have! ... Ken Cook Co, not "cheap" about $50
Joe B
Thanks Joe.. yes I have the service manual... and my model is V4AL13F
It may be a while before I pull the boat out and restart the engine, but I will make sure I have voltmeter handy to check for 13-15 volts.. I am fine with idle checks, I just didn't want to get into 3/4 throttle and switching to some sort of test prop.
And thanks for the tip on the ignition key-on discharge.
But, I could use a description of the 60 amp fuse... what color is it/ How big is it, does it come out easily? is it soldered or plug, or with a screw terminal or something? Is it right there at the lower right of the circuit box after I slide out the heat sink?
Thanks.
It may be a while before I pull the boat out and restart the engine, but I will make sure I have voltmeter handy to check for 13-15 volts.. I am fine with idle checks, I just didn't want to get into 3/4 throttle and switching to some sort of test prop.
And thanks for the tip on the ignition key-on discharge.
But, I could use a description of the 60 amp fuse... what color is it/ How big is it, does it come out easily? is it soldered or plug, or with a screw terminal or something? Is it right there at the lower right of the circuit box after I slide out the heat sink?
Thanks.
60 amp fuse.... I just went out and looked. The fuse is located at the lower right side of the junction box. It does not look like any usual fuse. Look for a bolt holding two square metal washers sandwitching a white ceramic waffer. Across the top of this waffer should be a strip of metal connecting the two square washers. This strip looks like a 1/16 inch square wire. The wire is the fuse... if it had burned you should see stubs where it melted.
Joe B
Joe B