MEP-802A noob, having contactor and 24v charging issues,, also fuel gauge inop.

[teletech]

I know I need to RTFM on the TMs, but I'm juggling an awful lot so hoping for a little luck and grace here.
Recent purchase of a 2005 unit in non-working condition (so they say). Filters, oil change, fuel, batteries, replace some return fuel line and the incomplete holder for F1, and it starts and runs. Heck it even makes AC! It won't charge the batteries unless I momentarily hot up the alternator regulator with V+ and then it runs and regulates. My VOM says diode 1 is still a diode, so either my VOM is lying to me, the diode is being sneaky, or something else is up. Thoughts?

Fuel gauge doesn't read at all. I'll dig into it, but thought I'd mention it in case theres a "oh, this thing always happens" answer I should start with.

The most pressing problem is actually on the AC side. It makes power as I said, but seemingly randomly throws a overload error. It's done this in single-phase 220 mode charging an EV and genset load about 25% and also in 3-phase mode running a big 3-ph space heater (environmental control unit) and energy reading about 55%.
It never happens when I'm looking at the unit, but seems like whenever I turn my back it trips and the contactor opens up. Reset the fault and engage the contactor and you are back to making power.

I also replaced the external supply fuel pump, dozens of fasteners, and straightened some sheetmetal.

Thanks folks,

 

[Ray70]

For the overload issue, get a can of Deoxit contact cleaner and spray and vigorously exercise both the AC select switch ( need to remove front top cover to clean the switch internals ) and also the AM/VM selector switch on the front panel. Get the cleaner inside the switch through the holes and small gaps in the switch bodies, then exercise the switch, then repeat.
Lets get that fixed, then move on to the charging alternator and fuel gage.

 

[teletech]

For the overload issue, get a can of Deoxit contact cleaner and spray and vigorously exercise both the AC select switch ( need to remove front top cover to clean the switch internals ) and also the AM/VM selector switch on the front panel. Get the cleaner inside the switch through the holes and small gaps in the switch bodies, then exercise the switch, then repeat.
Lets get that fixed, then move on to the charging alternator and fuel gage.

That seems to have done the trick! About half a fair size spray-can of some old tuner-cleaner I had on the shelf followed by a little deoxit.
Just a few hours runtime with loads from near idle to 75% and an A/C unit starting and stopping in there as well as a bit of an overload and it ran through it all, so far at least. I'll want several more hours runtime before I trust it, but it was a great start.
Next I need to figure out the alternator situation.

 

[Digger556]

For the overload issue, get a can of Deoxit contact cleaner and spray and vigorously exercise both the AC select switch ( need to remove front top cover to clean the switch internals ) and also the AM/VM selector switch on the front panel. Get the cleaner inside the switch through the holes and small gaps in the switch bodies, then exercise the switch, then repeat.
Lets get that fixed, then move on to the charging alternator and fuel gage.

I can attest that this works. I have an 802a that could not hold any load over 500 watts without throwing an overload after 1 minute. After Deoxit'ing it , it happily pulled 5000 watts without missing a beat.