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7.5 Breaker tripping (MEP-004)

steelman101

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Trying to sort out MEP-004. A few months ago was fighting fuel issues. Rebuilt IP, ran fine when picked up, Back at the shop it will run for less than 1 minute and the 7.5 breaker trips. Reset and restart with same results. Any Ideas, bad breaker or time to call electrician?
 

Ray70

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This is the DC breaker you're talking about I assume?
My suggestion is to 1 by 1 remove DC powered items until you find the issue.
When first attempting to start, I assume you are able to fill the day tank with the electric fuel pump with no issue? if so, that probably eliminates the fuel pump and solenoid.
next thing I would suggest is the IP solenoid. Disconnect the power feed wire and power it directly from the battery using a jumper wire and a 5A fuse.
See if the breaker still pops or if the fuse pops.
If neither pops I would try a 7.5A fuse in place of the breaker to verify the breaker is ok.
 

Guyfang

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Start with disconnecting the:
1. Battery charging alternator.
2. Both electric fuel pumps. The set should run for 15 min, on just the day tank.
3. The IP, like Ray wrote above.
4. The fault indicator. It should pop its own fuse, if something is bad. Unless its over fused, or has tin foil wrapped around it.
5. Look at CB1. That's the 7.5 amp circuit breaker. Look at the wires going to it. Are they showing signs of being hot? Look at where the CB1 wires go through the relay table. VERY often, the plastic ring that is supposed to protect the wires going through this hole, is gone. Some times the wires get worn through. Sometimes they make contact after a while because of vibrations.
6. Look at the doors. Yes the doors. The inside of them. Mainly its the left side rear door. The wire harnes, often is loose and the wires touch the door. The wires vibrate, and wear through. Sometimes they touch the metal door. You can see signs on the door where a wire arc's. A burn spot, if you will. Pop goes the CB1. Ask me how I know this.
7. Replace the CB1.
8. If by then you have not found the problem, start looking at every wire harness that goes near metal.

If that brings no joy, we can really start digging.
 

steelman101

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I live in Cornelia, Ga.
I have a MEP 004A 15KW, it has been an adventure to get this unit to run at my shop, after I bought it or after I had the IP rebuilt.
As soon as I got it back it started to trip the 7.5 CB-1.
I have been trying the suggestions that have been offered.
Is there anyone near me who is familiar with this unit? I will only screw this up.
Thanks
 

steelman101

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Welcome to the site!
How's it going?
I bought this a year ago and it has been one thing after another. Now it is the CB-1 breaker. I know nothing and the electrician's around here when first approached scratch their heads when talking a military piece.
Still hopeful.
Later
 

Guyfang

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OK, When you took out the the IP to repair it, what else did you do?

When does the CB1 pop? When you push it in, and the S2 is in the off position? Or after you push in the CB1 and turn the S2 to the start or run position? Or after it starts and runs? I need some info here.
 

Guyfang

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I wrote on 13 Oct 2023:

Start with disconnecting the:
1. Battery charging alternator.
2. Both electric fuel pumps. The set should run for 15 min, on just the day tank.
3. The IP, like Ray wrote above.
4. The fault indicator. It should pop its own fuse, if something is bad. Unless its over fused, or has tin foil wrapped around it.
5. Look at CB1. That's the 7.5 amp circuit breaker. Look at the wires going to it. Are they showing signs of being hot? Look at where the CB1 wires go through the relay table. VERY often, the plastic ring that is supposed to protect the wires going through this hole, is gone. Some times the wires get worn through. Sometimes they make contact after a while because of vibrations.
6. Look at the doors. Yes the doors. The inside of them. Mainly its the left side rear door. The wire harnes, often is loose and the wires touch the door. The wires vibrate, and wear through. Sometimes they touch the metal door. You can see signs on the door where a wire arc's. A burn spot, if you will. Pop goes the CB1. Ask me how I know this.
7. Replace the CB1.
8. If by then you have not found the problem, start looking at every wire harness that goes near metal.

If that brings no joy, we can really start digging.


You might try and answer the questions also.
 

jamawieb

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When does cb1 trip? Turn the master switch run, turn the battle short on, does it trip? If so the fuel pumps have capacitors that short and will trip cb1. Just have to cut the capacitors out and splice the wires together.
 

steelman101

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Georgia
OK, When you took out the the IP to repair it, what else did you do?

When does the CB1 pop? When you push it in, and the S2 is in the off position? Or after you push in the CB1 and turn the S2 to the start or run position? Or after it starts and runs? I need some info here.
Hello,
At first it would run fine but there was a problem with the IP causing it to shut down . Had the IP rebuilt which was the only thing I had rebuilt. It ran fine at the repair shop. I get to my shop and the CB-1 starts tripping. I followed your directions earlier. I found no burnt or rubbed raw wire. The fuel pumps run but not the five or ten minutes stated for the day tank supply.
I tried to find a way to email you the video of the start and CB-1 tripping.
Now the CB-1 trip's as soon as I hit the S-1 to start.
I was going to get a multi-meter and from what I read hook it in line and see what amp it trip's at. Told it should handle 15 to 20 amps if it is good. I took it to a electric shop and they said it was letting current flow thru. But could not tell me if it was weak and easily tripped.
That's where I'm at now.
I really hope it is the CB-1 has gone bad??
Thanks Harold
 

Guyfang

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Two things that are easy to to check.
1. Unhook the canon plug to the battery charging alternator. try and start it. If the CB1 doesn't pop, the alternator is the problem. Leave unhooked if the CB1 pops. .
2. Unhook both wires to the electric fuel pumps. Try and start it. If the CB1 doesn't pop, the one of the fuel pumps is the problem. Leave unhooked if it the CB1 pops.
 

jamawieb

Well-known member
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Location
Ripley/TN
Hello,
At first it would run fine but there was a problem with the IP causing it to shut down . Had the IP rebuilt which was the only thing I had rebuilt. It ran fine at the repair shop. I get to my shop and the CB-1 starts tripping. I followed your directions earlier. I found no burnt or rubbed raw wire. The fuel pumps run but not the five or ten minutes stated for the day tank supply.
I tried to find a way to email you the video of the start and CB-1 tripping.
Now the CB-1 trip's as soon as I hit the S-1 to start.
I was going to get a multi-meter and from what I read hook it in line and see what amp it trip's at. Told it should handle 15 to 20 amps if it is good. I took it to a electric shop and they said it was letting current flow thru. But could not tell me if it was weak and easily tripped.
That's where I'm at now.
I really hope it is the CB-1 has gone bad??
Thanks Harold
Unplug the fuel pumps first and try to start. See if it pops after they are unplugged.
 

steelman101

New member
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Location
Georgia
Two things that are easy to to check.
1. Unhook the canon plug to the battery charging alternator. try and start it. If the CB1 doesn't pop, the alternator is the problem. Leave unhooked if the CB1 pops. .
2. Unhook both wires to the electric fuel pumps. Try and start it. If the CB1 doesn't pop, the one of the fuel pumps is the problem. Leave unhooked if it the CB1 pops.
Hello again,
I followed your directions and I know you would never believe it!!
It turned out that it is the brand new fuel pump that I had replaced with the IP.
That is a step in the right direction, but then comes the new issue.
I turn on the Battle switch with the new pump un-plugged and the old pump runs just fine and I hope it is filling the day tank.
But now I have no power to the Test Panel?????
The starter engages fine but will not fire off.
What do you think caused me to lose power to the Panel??
 

steelman101

New member
16
7
3
Location
Georgia
Hello again,
I followed your directions and I know you would never believe it!!
It turned out that it is the brand new fuel pump that I had replaced with the IP.
That is a step in the right direction, but then comes the new issue.
I turn on the Battle switch with the new pump un-plugged and the old pump runs just fine and I hope it is filling the day tank.
But now I have no power to the Test Panel?????
The starter engages fine but will not fire off.
What do you think caused me to lose power to the Panel??
Guyfang,
I pulled the 1 amp fuse and replaced it.
Hooked the Batteries up and the the test light for oil low pressure was on. Pulled the lever and the lights came on and then went off. Replaced that fuse and the only light besides the oil was the low fuel light was off.
Tried to start but no luck. I left the bad pump unplugged and could hear the original one pumping away. How long should it take to fill the Day Tank?
Thanks.
 

Guyfang

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Should not take but a few min. with one pump. Have you checked the three way fuel valve to see if its in the right position? Is the low fuel light on?
 

steelman101

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Location
Georgia
The low fuel light was on with the low oil. I filled the tank but the fuel gauge only comes up to 1/4. Now when I set to run I hear no fuel pump till I turn on the Battle switch. It will start and run, but as soon as I shut that down the engine shuts down. Which way is the IP handle supposed to be facing the front or rear? I had moved it forward I moved it back and it started up. I called the group who installed the IP, due to small leaking I noticed from the backside, maybe a loose line??
I ran it for about 30 minutes, the oil stayed at 29/30 lbs, but the temp never came up.
What is the leaking black sticky substance coming out of the bottom @ left side of the control panel?
I feel like I'm paying "Whack-a Mole" Get one and another pops up.
Thanks for you time.
 

Guyfang

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You are making this more complicated then it is. You need to understand how the generator should work. Reading the -12 TM would help a lot. Also, answering questions people post here would help a lot. We can not be there, so you are our eyes and ears. If you don't tell us the things we need to know, helping you is hard.

The generator is designed to NOT start with certain failures in it. It will crank, but not start. Number one is "NO FUEL. When that circuit is lit up, that means the sen set is so low that the military doesn't want you to run or crank the gen set till the fuel system is dry. OR, it means that the FL! and FL2 Float switch is not working right. OR, it means that the electric Fuel pumps are not pumping fuel to the day tank. This is a "Show Stopper" Fault. You need to correct THIS fault before anything else. AND, It might fix other fauls at the same time. Make it run first, then clean up the small stuff.

YOU wrote:

The low fuel light, (Show stopper. This light is only on when you have bigger problems.) was on with the low oil. (This light should ALWAYS be on when the gen set is not running. Not running, no oil pressure. If its on while running, could be a problem. But prestart, in the start funtion, and before the engine hits is normal RPM, NOT a show Stopper) I filled the tank, (What tank? The Day Tank or the Set Tank?) but the fuel gauge only comes up to 1/4. (Not a show stopper. Pull the MT3 (Fuel tank level sender) out of the set tank and clean it, and inspect/TEST it IAW the -34 TM. After its out and clean, (and the float is often full of fuel), you can hook the wire back up and move the float up and down to see if the M3 Fuel level meter functions. You need to ground the MT3 to make it work right. But its NOT a show stopper and can be done later. Now when I set to run I hear no fuel pump till I turn on the Battle switch. (Why should you hear the fuel pump run? If the FL2 is telling the generator set that the Day tank is full, then the fuel pumps will NOT come on. If the electric fuel pumps come on with the S7 on, that tells you that the pumps work. We need to know if the pumps come on fast, then slow down? Or fast and never slow down? Are both pumps running? What kind of "New Fuel pump" did you put in? The SAME as the old pump? Because lots of pumps LOOK the same, but are NOT the same. Will the Day tank fill up? How fast? These are all questions that help find the problem. It will start and run, but as soon as I shut that down the engine shuts down. (Because the NO FUEL situation tells the engine to stop) Which way is the IP handle supposed to be facing the front or rear? I had moved it forward I moved it back and it started up.
(See the below picture to know how the IP and arm should be set up. Whan you had someone fix the IP, its always a good Idea to give them the -34 TM section on repair and adjustment of the IP. The Army and civilians do things differently. )

I called the group who installed the IP, due to small leaking I noticed from the backside, maybe a loose line?? (Could be that the injector bolt is not tight enough. Could be that one of the TWO washers that are supposed to be on the injector line bolt at the IP is missing. OR not installed properly. Happens OFTEN. Get a small mirror and look. Who installed the IP back on the set? You or them?)

I ran it for about 30 minutes, the oil stayed at 29/30 lbs, but the temp never came up. (This is NOT a Show stopper yet. Needs to be addressed later. Has nothing to do with starting and running. )
What is the leaking black sticky substance coming out of the bottom @ left side of the control panel? (The A1, Thermal Watt Converter is bad. Open the control panel and look to the right side. You should see where its leaking. The second picture shows an A1. Some are plastic, some are metal. Mostly the plastic ones leak.)

The gen set is supposed to be looked at from the control panel end. That is the rear side.


I feel like I'm paying "Whack-a Mole" Get one and another pops up.
 

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