2007 Df300 engine died while running

[Neil Owen]

Looking for any help , I have a 2007df 300 , while I was running yesterday at 35mph for 15 minutes the engine died and said low voltage on the smis gauges. It would start back sometimes and run for 2 minutes then die. Then sometimes it would not start ,but it would turn over but would not fire off. Any suggestions wha it might be . I check the fuel filter as it has been changed in the last 5 hrs and it looks good. And the batteries were charged , and tilt and trim is working and the motor turns over.
Thanks
Neil

[Moonlighter]

Check the white wire, it should be connected to the positive side of your main battery switch or direct to the battery.

This wire is bery important - provides power to the engines ECU and if it gets loose, corroded, pinched or otherwise damaged and power to the ecu is compromised, then you get problems and things like low voltage warnings can point in this direction.

While you are there, check all battery connections. Any by "check", i mean undo them, clean them, and reconnect them and tighten firmly. Same process for the white wire connections.

[Neil Owen]

Thanks I will check it as I replaced the batteries about 2 months ago all the connections were clean and tight . It could have came loose it will be a few days before I'm back at the boat . If I do this again and clean the connections and tighten them and it still does the same thing , what else could it be? I'm just trying to be prepared if this doesn't solve it. and what the next step would be.
Thanks for your help

[redlowrey]

If you had not said that the low battery warning light come, on I would have thought you had a fuel problem. Did you pull the racor fuel filter off and check it. Could you hear the fuel pump when you turned the key on and when cranking, and when the engine died was it like you turned the key off, or did it splutter and die. If it is electrical you will need to do some voltage drop tests.

[Neil Owen]

I tired the white wire, and loosen it, clean and re-tighten it. It does the same thing. I also check the racor fuel filter it was clean. It runs fine the just dies like the key has been shut off. No spluttering. But just says low voltage, one time it said check command shift as well, but i believe that was it was still in forward gear from when it died . What kind of electrical test you recommend. Could it be the neutral safety switch going bad?

[redlowrey]

If the switch failed closed while the engine was running it would limit the rpm to 3000, if it failed open when trying to crank nothing would happen, if you bypassed the switch straight to the starter it won't start the ecu won't put a ground on the injectors. check all the fuse voltages both sides and check 15 30 60 amp fuses on the motor with a digital multimeter. when you first turn the key on you should hear the fuel pumps prime for a couple of seconds and then stop, With the key on check the voltage on your injectors, coils, fuel pumps, it should be over twelve volts if it is it tells me that the power relay is switching, if it is a lot less go to your main control relay or post back your test result. Mate this is only one test of many, but your main control relay distributes power to a lot of components and the ecm.