MEP-003 DC breaker popping

[amolaver]

I think I've had the generator about a year. I run it about every two weeks for an hour or two to test, and we've relied on it for about 3-4 multi-hour outages, and one 4 day run. It's been fantastic operating my all-electric house (heat pump, hot water, washer/dryer, well pump, etc).

A couple months ago, when running on the aux fuel (pulling from a 55gal drum right next to the generator), the generator shut down, and when I checked on it, the DC breaker had popped. Further attempts to run on aux triggered repeat behavior - popped DC breaker. With the gen motor stopped, turning the main switch to aux (engaging the pumps and I'm not sure what else) would trigger the DC breaker to pop. So, with a thousand other projects being juggled, of course I said, 'I'll get to that later.' And just started running from the day tank.

Last weekend I was doing my normal 1-2 hour test running (from the day tank), and now the behavior has shown up in the 'normal' (non-aux fuel) running position. Gen ran for 30-45 minutes totally normal, then shut down. Check on it, and DC breaker is popped. Again, with motor stopped, putting the rotary knob in the 'run' position WILL pop the DC breaker.

I spent some time trawling the TM's, but I don't see any real DC diagnostic procedures. I did pull the strainer's on the pumps and all 3 looked clean. I am not sure what other bits and bobs beyond the fuel pumps are powered in the run/aux fuel position. Given the similarity in behavior in the two different operating modes ('normal' vs aux fuel), it would seem likely to me the pump(s) are involved in the problem. Is there GPM+amp draw test/spec for the pumps? Any recommended places to look for wear on wires that might be shorting? Any recommended triage steps? Thanks!

ahm

 

[doghead]

The noise suppressor on the fuel pump wire is known to short out, and cause the dc breaker to kick out.

Unbolt it from the frame, and see it that solves your issue. If it does, simply remove it(butt splice the wire back together).

We do not need the suppressor.

 

[amolaver]

thanks - will remove the rfi suppressors from all three pump circuits and test. if those are the culprit, are they available as a separate part to replace?

just for additional info, in either aux or 'normal' run modes, the pumps do SOUND like they are working for a 2-5 seconds before the DC breaker pops.

ahm

 

[Jimc]

you dont need the suppressors. take them all off the unit. i remove all of them on all the generators i have done. just another thing to go bad and cause an issue.

 

[amolaver]

unfortunately, its not the suppressors. All three have been cut out of the circuit and a butt splice for each is in its place. still popped the DC breaker. started unplugging the pumps one at a time, and sure enough, with the pump 'on the corner' (the one by itself, not either of the siamesed together pumps) unplugged, gen runs. so, it looks like i need a pump.

i've read lots of conflicting info about what an appropriate replacement would be..other than the $300 OE facet. anyone have any cheaper alternative pumps that they can vouch for, or am i stuck buying a $300 fuel pump?

ahm

 

[Munchies]

unfortunately, its not the suppressors. All three have been cut out of the circuit and a butt splice for each is in its place. still popped the DC breaker. started unplugging the pumps one at a time, and sure enough, with the pump 'on the corner' (the one by itself, not either of the siamesed together pumps) unplugged, gen runs. so, it looks like i need a pump.

i've read lots of conflicting info about what an appropriate replacement would be..other than the $300 OE facet. anyone have any cheaper alternative pumps that they can vouch for, or am i stuck buying a $300 fuel pump?

ahm

Search the 'large unnamed auction site' with nsn's and part numbers. occasionally there will be nice priced NOS pumps.
http://www.steelsoldiers.com/showthread.php?95457-Facet-fuel-pump-alternate&highlight=facet
http://www.steelsoldiers.com/showthread.php?30909-Fuel-pump-needed&highlight=476088

 

[Harleyd315]

Try Aircraft Spruce for Facet replacement pumps. I have gotten some Airtex 24volt fuel pumps at Rock Auto and they seem fine, just have to use some adapters or change fuel line. Also the gen will work just fine with one pump, or if you never plan on using the aux fuel option you can use that pump also.

 

[dangier]

amolaver,
The first thing I do on a new (to me), 002 is take all of the fuel pumps off, clean up, and put one from the tandem setup on the shelf for spare. Like Harleyd315 says, you do not need two pumps in tandem.
Nice troubleshooting in finding the problem!
David