Starter wiring on Onan MDJE diesel generator

[Bob Bradley]

I need some help reinstalling the starter on my Onan MDJE diesel generator. I made the mistake of not marking the wires when I removed it last fall, and now I can’t figure out where they go.

Here’s what I have, and what I do know:

12 ga black wire obviously can only go to the #10 size post on the solenoid.

Solenoid has 2 other posts: 5/16” with nut.
Starter has what appears to be a ground bracket, with wires attached via a nut and bolt.

Wiring is as follows:
Large (approx 2 gauge) Red 12v + wire from battery
Large (approx 2 gauge) Yellow – wire that attaches to ground bar in circuit box.
Medium (approx 6 gauge) Yellow wire to unknown destination.
Medium (approx 6 gauge) Green wire that attaches to ground bar in circuit box.

I’d appreciate any and all help, as I’ve done it wrong twice now (once resulting in burning out a 350amp fuse), and it takes about 4 hours to remove and reinstall the starter. My local Onan guy can’t provide a diagram of how the starter is wired.

[dshuman]

Onan can get you the complete parts manual and the repair manual. You can find a better "local guy" by doing a dealer search at Onan.com. I got manuals for my MDJF from the following:
Cummins NPower LLC
7145 Santa Fe Drive
Hodgkins IL 60525
Phone: 708-579-9222

[dshuman]

By the way, the MDJF (15KW) generator starter only shows two wires to the starter, excluding the ground. There's a very large ga. wire from the battery + to the big starter post on the solenoid and a smaller ga. + wire to power the solenoid to the smaller post on the solenoid. Grounding is done theough the engine block for both the starter and the solenoid.

The idea is the smaller wire energizes the solenoid and the movement of the solenoid both engages the drive pinion and connects the big battery power wire to the starting motor. This connection is made inside the solenoid.

Sounds like your setup is different. Could the 2nd smaller post be for a second remote starting swicth?

I'd call Onan.

[skammtoo]

Bob, who are you using for service? I may have someone better for you for generator and ac work.

Capt K:\

[Bob Bradley]

Thanks for the replies. I got ahold of a schematic late Friday and traced it out finally on Sat evening. Seems someone didn't follow the color coding on the boat/unit. There is a 12v + jumper from the positive post of the starter solenoid that powers the fuel solenoid. Whoever installed it used a 6 ga yellow wire. Everything else yellow on the Hatt is ground, so I had grounded it, effectively shutting off the fuel supply. The second 5/16 post didn't come into play. That connects a copper strip directly into the starter body. She's up and running now.

Capt K, If you know someone good in the Conn area, I'd love to have is contact info.

Bob

[skammtoo]

Bob, I've been using Larry from C.S. Miller Yacht Engine Service for over 10 years. He is a wiz with gensets and great with the older air/heat systems. He's maintained my AC units for years. Last fall I finally had him replace the last two units that he had not done and he corrected all of the wiring and put in the proper relays, etc. Very clean and reasonably priced.

Time service is a little slow, but he's mostly a "one man band" so you have to plan ahead when possible, although he is right there for an emergency.

He's in Saybrook. If you need him, tell him Kevin from Skamm Too referred you.

K

[Bob Bradley]

I met him last year when I replaced my charger. Very knowledgable guy. He even loaned me his "classic" heavy duty wire crimper so I could do a professional install on the big wires to the charger.