Diagnostic Start

Dear Postman,

First thing's first, wheels and track clean?

Second, when did you buy the loco? Was it factory DCC+sound equipped?
Early Ath MP15s were equipped IIRC with MRC decoders which at-the-time had a rep for unreliable running.
(Not saying this is certainly the issue, but it's worth filing in "related information").

3rd, has it only just started misbehaving, or has it been like this since Day 1 of operation?

If you've had the loco in service for a while, any chance it may have picked up any scenery or grot in the axles/bearings? The typical Horizon-Hobbies-era Ath has a clip-on cover on the bottom of the truck.

(Pic of a similar SW1500, note the little clips inboard of each axle, holding the lower cover plate on)

Place the loco upside down in a service craddle or similar, carefully pry the cover off, there are clips on either side which need to be released, and the axles/wheels/gearing/bearings will be exposed. 

From here, get a lot of light on the subject, and with fine tweezers make sure that any/all grot is removed.

Assuming you have checked all of the above, and still no obvious issues or improvement, time to get the shell off, and check the pickup wires running from the truck to the PCB. (being a Genesis-series model, it should not have the old-skool Blue-Box Ath "spring system"). At the PCB, check to make sure that the little plastic retainer for each truck wire hasn't wiggled loose, 

I would also suggest using the MRH search function with the search terms "Athearn diesel problem",
there have been good diagnostic threads covering many Ath models with broadly-applicable "methods of diagnostic attack" worth boning-up-on...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Had the same problem

I have an MP15 with Tsunami sound and had the same problem.  There is a thread on this on the forum, but can't seem to find it.  

I switched out the drive wheels with a set from NWSL.  That helped a bit, but didn't cure the pickup issues entirely.  In addition, I found tht a couple of the truck side frames which contain the wheel contacts were a bit loose and would wiggle.  That's really bad for contact.  Suggest you check them for any movement.   I added a drop of glue to each and clamped them together until they dried.  This actually helped a lot.  Still had a stall here and there, but much less.  I have found that as I have run the loco over time, the problem has gone away.  I'm not sure why, but it has.  Runs perfect now.  

By the way, had the same issue with my Athearn Genesis (Tsunami sound) F7A/B units.  Fixed them the same way.

John C

Found the original thread

http://model-railroad-hobbyist.com/node/16295

John C

I think oil has gotten into

I think oil has gotten into the axle and pick-up bearings. Do you have pictures of how to disassemble and remove the cover of the trucks?.

Athearn genesis MP15AC issues

I also had this problem and I found a thread that helped cured my units problem - and I can't remember where I found it ........ But I did find the problem and cured it .....

The axle arches on the gear towers were not deep enough and fouled the wheel axles preventing correct loading of the axles in the bearings were the electrical pick up was made.

I also found the the unit lost its electrical connection when rounding a bend - seemed to be caused by loose wheels. When I striped the unit I found that both Side Frames were bowed outwards – straightening these frames has cured the ‘loose wheel’ problem.

Now I have a nice well behaved little MP15.

Happiness!

Check this video addressing these problems and the fix for it.

check the basics first...

Very true!

As with checking the basics first, can't say enough about that.  Make sure it is mechaniaclly sound before you begin a "tune up"!   

Case in point:  One of our jr techs at the marina one day clocked in on a "engine runs rough, lacks power complaint"  (3 cylinder 40 HP 4 stroke outboard)  Started and run engine and confirmed issue of rough running and procceded to do a full tune up including rebuilding the carbs, flushing the fuel system replacing 3 new spark plugs, ect......with the same results as he had before!  Ran rough, no power ect!  Here is where I come in (sr lead tech) as I asked him how did the basics check out out before he did the "tune up".  He had not done the basics!!!!    Spark, compression and fuel quality!  Compression on # 2 cyl was 0 PSI as it had burned a valve!  No tune up will fix that!!!   (by the way, we ate the bill on that one!!)

Cleaned truck housings and parts

Hello all. The issue is fixed, cleaned gears, wheels and pick-ups with isopropyl alcohol and now it runs well. My advice, always oil your locos sparingly!.

Manolo