MEP 003A, CB2 DC Circuit Breaker Trip

[Floydla1]

Hello Gents,

During the genset's weekly exercise the CB2 tripped. The MEP 003A started fine and ran almost an hour (main CB1 off). When I reset the breaker and attempted restart it tripped again when I moved master switch S1 to prime. My first impression is that I have a bad fuel pump or solenoid valve. I would appreciate an experienced voice advising on a diagnostic protocol. I have not found one in the manuals but that is not to say its not there.

I need to get a spare pump or two anyway, so if someone has some they want to sell, please let me know. National stock number of mfg codes are 2910-00-930-9367 and 72-5313 respectively.

Thanks much, Larry

 

[Light in the Dark]

Do your pumps still have the inline EMI filter? Have you disconnected the pumps and tried to turn the S1 on and see if the breaker still pops?

If there is a short in that block, they can be cut out and the wires respliced.

 

[Floydla1]

Hello Light in Dark,

I do not have an inline EMI filter (but based on my experience with my Mercedes 300SD it makes a bunch of sense. The filters have the integral strainers. I checked them and they are clean. I checked each pump by disconnecting power from each. The first pump out of the fuel tank trips the breaker.

 

[robertsears1]

Not trying to insult your intelligence, but the EMI filter is to stop interference on radios, nothing to do with fuel. You can cut them out since they are usually superfluous. Sometimes they cause problems. Your answer to me seemed to indicate you misunderstood what he was trying to say. Perhaps you did understand and then started talking about filtering the fuel.

Robert

 

[Light in the Dark]

Care to take a photo of your pump(s) and arrangement?

 

[jamawieb]

I agree its the EMI filter on the fuel pump. Follow the wire you disconnected for the pump that tripped the breaker, does it go to a square box or cylinder type contraption before getting to the actual pump? If it does, that is the EMI filter. Cut it out and splice the wires together.

 

[Floydla1]

Hi Guys,

So to be sure, nobody is insulting my intelligence, and I have a sense of humor (laugh at myself often). I am guessing now that EMI means "Electro-Magnetic Interference" and has nothing to do with the fuel line. This is a dead giveaway that I am non-military. Sooo, there is no contraption like jamawieb describes that is between the power source and the pump -- the wire goes straight in to the pump housing. Attached is the nameplate picture. I can send a picture tomorrow of the pumps tomorrow -- it is dark now. Thanks much!

 

[Floydla1]

Well actually, I do have a picture of the genset where you can zoom in on the fuel pump block. I don't know if this helps.

 

[jamawieb]

Well actually, I do have a picture of the genset where you can zoom in on the fuel pump block. I don't know if this helps.

Need to get a picture of the opposite side. The EMI filters are mounted on the inside of the fuel pump mounting bracket.

 

[Guyfang]

There are several versions of the "E-Pump". The first version was simply a E-Pump and a wire from it, to the rubber connection. Attached is a picture of the second version. See Item #20? Follow its cable to a round thingie, (if you look at whats between item #'s 17, 18, and 19, you can see about what it looked like. Its the RFI. The third version had a "metal box" that was also the RFI. If your pump is bare of these RFI's, then you have a OLD pump, or a pump that looks like the right pump, but may not be.

If your pump has no RFI, and pops the CB, then toss it out, get another.

Below is a list of NSN's that will also fit your gen set. Add the first 4 numerals to it, 2910-

00-092-9331 00-456-1261 00-918-0609 01-076-3910 01-195-9690 01-210-8748 01-366-8110 01-455-3197

The list of part numbers is so long, I would need a half day to write them.

0303-6003
106092
10910278
123124A
123124A
149-1105
149A1105
2590174
29109309367
479028
6-4444681
6052
6052
6054
9375412
C4U9028
FRB-15
M62678-2-24N1
MIL-P-45328
MIL-PRF-62678A
MS51321-2
MS51321-2-24N1
MS51321-2-24N1

Try looking for both the NSN and part #'s. There are pumps to be found for less money. BUT it has to be the kind of pump, that will allow fuel through it if it fails.

 

[Light in the Dark]

The cheapest I found the Facet 480517E was at Yacht Supply Depot (https://www.yachtsupplydepot.com/), but their website doesn't seem to be working now... Was previously $189/ea. This is the same OEM unit that Green Mountain has up, with the in line EMI filter. There are other pumps that have been adapted to work, but I like going with what was intended (until the filter fries, then its what was intended... except for that).

 

[Floydla1]

First, thank you all for the rapid, and accurate responses. Guyfang's exploded diagram really helped. I have posted two pictures that confirm no RFI, and there is evidence the prior owner already did the splicing. I found the Facet pump on Pegasus ($218/ea). Somebody else posted on the web page that they replaced their MEP003A pumps with these and they worked great. I ordered three -- free shipping and no tax .

 

[Guyfang]

The cheapest I found the Facet 480517E was at Yacht Supply Depot (https://www.yachtsupplydepot.com/), but their website doesn't seem to be working now... Was previously $189/ea. This is the same OEM unit that Green Mountain has up, with the in line EMI filter. There are other pumps that have been adapted to work, but I like going with what was intended (until the filter fries, then its what was intended... except for that).

The Facet pump 480517E has been replaced by the military, by Facet 40128E. The only difference is that the 40128E has a "Positive Shut off Valve" and the 480517E not.

Attached is the Facet catalog. If you go into it far enough, it even has a Military NSN listing, and what Facet number fits it. AND, spare parts, farther on. Thats worth its weight in gold.

This is the second thread in less then ten days on MIL-STANDARD E-Pumps. Perhaps we need to put all this info into one package, and have this info all in one place?

 

[Chainbreaker]

The Facet pump 480517E has been replaced by the military, by Facet 40128E. The only difference is that the 40128E has a "Positive Shut off Valve" and the 480517E not.

OK, now I'm confused...I thought you wanted the pump (Facet pump 480517E) without the "Positive Shut off Valve" due to the MEP-003a & -002a's having 2 pumps in series so it could always pump through a dead pump? The 2018 PDF sheet still has both the pumps listed and the only difference being one has the positive shutoff and the original spec'd pump for -002a/-003a does not have the positive shut off valve.

I could see using the 40128E for the Aux fuel pump, but if I understand this correctly...that would limit it to never being available to be swapped out as a backup to the primary or secondary fuel pump if you want to preserve the fail safe pass-through feature if having 2 pumps in series, that is unless only run as a single primary pump configuration.

 

[Guyfang]

All I did was post what was in the ARMY FEDLOG. I should have wrote that the perfered pump is 480517E, but for some reason the milatary went to another pump. Probaly because this type pump is still used all over the milatary fleet, in all kids of equipment. But in the norm, most equipment still using it, wants/needs a PSO, (Positive Shut Off). For all DOD gen sets, (002A up to 007A) the is needed.

 

[Floydla1]

Good evening all. I may be chasing a rabbit, and need to start a new post -- just let me know. After ordering the 24v E-series pumps, it prompted the question -- what part(s) should I keep my eye out for that are rare / expensive? Another way to phrase the question -- for your genset(s), what part(s) would you feel uncomfortable NOT having in your spares? For me, the answer was the main breaker.. I confirmed through Newark they are obsolete and ordered one from Green Mountain today. Spares I already have: Exciter (rotor), voltage regulator boards (2), metered fuel pump, glow plugs, injectors, and reactor. What am I missing?

 

[Floydla1]

An update on the pump replacement. Purchased three of the pumps on Pegasus ($218/ea). They were in stock. Ordered Wednesday, received Saturday. Free shipping, no tax. P/N FAC-480517, Description: Facet Cylindrical 24v Fuel Pump, 1/4 NPT, 6-8 psi, EMI.

Installed today. Problem solved. Runs great. Thanks again.

 

[Neophyte]

Great post! Popped the DC breaker and spent a good hour looking for a short to ground. Read this post, found the 1st pump was bad (After removing the capacitors on all three pumps)..Ordered a new one (thank you Guyfang), soldered and heat shrinked the wires together.

Thank you!

 

[Guyfang]

Its the first place to look. 99.99% of the time, thats where the problem is.

 

[Chainbreaker]

Good evening all. I may be chasing a rabbit, and need to start a new post -- just let me know. After ordering the 24v E-series pumps, it prompted the question -- what part(s) should I keep my eye out for that are rare / expensive? Another way to phrase the question -- for your genset(s), what part(s) would you feel uncomfortable NOT having in your spares? For me, the answer was the main breaker.. I confirmed through Newark they are obsolete and ordered one from Green Mountain today. Spares I already have: Exciter (rotor), voltage regulator boards (2), metered fuel pump, glow plugs, injectors, and reactor. What am I missing?

A few years back I asked the same question when I bought my 1st MEP-002a and I too listed & questioned keeping a few key spares on hand. It was suggested by a long time SS member that if you add up the cost of buying "critical spares" you could in all likelihood buy a complete spare unit.

At the time, just after buying my 1st unit, that recommendation sounded a bit extravagant. However, after buying a few "critical spares" of this-and-that (oil pressure sensor, thermal switch sensor, IP plunger guide, VR board output transistors, starter motor, injectors, as well as a complete AC Reconnection box and Control panel) plus other parts I can't even remember. It became apparent that virtually "all the parts are critical" to making the unit run and the "critical parts hoarding" would never cease!

So, after reflecting on the "2 is one, 1 is none" strategy, I kept an eye out for used running or non-running MEP-002a units that were repairable. Eventually my "be prepared addiction" brought me up to 4 generators (2 as spare units). This was required due to my property having 2 services entrances each with a well and a pumped septic system that must be powered during outages in addition to typical house, barn & shop "life as usual" & keeping the wife happy requirements.

So to answer your question... given "my situation" and having experienced 2 unrelated unit failures (T1 transformer failure & a thermal shutdown) during a couple of extended multi-day widespread area event outages, I would now feel uncomfortable not having a 1:1 ratio ready to swap in spare unit(s) at the ready. Sounds a bit superfluous, but in the long run for me it proved to be the cheaper more reliable & less stressful route. It appears that generators and parts prices will continue to rise due to events beyond our control while the grid doesn't seem to be getting any more resilient to power disruption events.