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MEP - 016b

Anthill

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I recently purchased a MEP-016b gen set with 73 hours on it. I got it home and found it was full of fuel and oil was clean so I bought a battery and it started right up. After running for several hours the control breaker tripped and it shut down. I reset it and it started back up only to shut down minutes later. It seemed like it was not getting fuel so I checked the filter and it was fine. Where should I check next ? Fuel pump maybe ? Any sugestions would be appreciated.

Thanks,

Ant
 

ETN550

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The fuel pump is mechanical and if it did not get fuel due to restriction it would stop running but not trip the breaker. If the fuel was low it would shut down automatically due to the low fuel float switch and would not trip the breaker. Only a direct short to ground in the 24vdc controls would trip that breaker. The electric fuel pump that is mounted on the frame at the bottom near the main tank only runs when the Master switch is in the Aux Fuel position. Then it will run to draw fuel from a user supplied tank using a user supplied hose attached to the electric pump and fill the unit tank until the float switch inside says the tank is full. It will proceed to re-fill the unit tank when the low float tells it to. For standard operation off of the unit's tank run the set with the switch in the position next to the start on the master.

I have had this same control breaker problem with some of the 016Bs that I have worked on. The easiest place to start if it trips consistently and quiclky is at the relays in the control box.

Open the front of the box, swing the top lid up and the relays are the small silver components screwed down to the control board on the left side of the box. there are four of them, K1 - K4. Take them out one at a time and you may find one that that is feeding the short. I'm not saying the relays are bad but rather by removing them you are taking out parts of the circuit and isolating the problem. When you remove one and the breaker no longer trips then the circuit controlled by that relay is the one to track down.

If the breaker does not trip right away and you can turn the switch to run and leave it there then go around shaking the wiring and tapping on the end devices with a screwdriver handle.

Two specific problems I had on separate units: One had a short on the plug for the fuel control solenoid. The other had a brand new electric fuel pump that failed and shorted. In both cases the control breaker tripped.

Most likely the problem is an end device or a wire rubbing through somewhere. Pull the side panels off for a better look.

The metal screw connectors do not fail, but the snap on plastic connector at the fuel control solenoid did on mine, and the relays are very reliable as they should be at $150.00 each.

The wiring diagram has a section on the 24 volt supply and end devices which is what that breaker controls. I like using the schematic and going to the table of contents for the end devices.

Once you find the circuit that is bad By unplugging the relays) unplug the end device and plug the relay back in that controls that particular end device. If the circuit trips then the wiring to that end device is bad, If the circuit does not trip then the end device itself is bad.

Sometimes it takes a while but you will find it and most of the repairs are not that expensive. Just the relays. BTW the relays are double sided so if one ever failed just remove it flip it over and re-install it. Most of them only use one side and the two sides are identical. Kind of like having a spare built in.

All components are labeled. The relays (labeled K1 through K4) on the right side of the board and you kind of have to stick your head in the box to see the labels. or use a mirror.

Please report back your findings so we all learn and congrats on your purchase of a fine machine.
 
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goodguyzy

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I had a similar problem and ended up swapping the breaker. I swapped it with another one I had and still cant find a replacement except for a site that sells 80 at a time.
 

Anthill

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I tried turning the relays around(K1 through K4) But it still won't run. I only had a problem with the control breaker tripping the one time, but thought that might be an indication that something else tripped because it happened right before I had the issue with it not running.

I took the fuel line off of the injector and there was no fuel in the line. There is no fuel in the filter either. There appears to be a fuel pump below the fuel filter mounted to the bottom frame rail. It only has one wire going to it I am assuming it is 24V + and it is grounded through the body of the pump. Is there a inline fuse or another breaker I should check ?
 

derf

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Now you know why it was DRMOd.
Like he said above, the relays are most probably not the problem. They are, however, troubleshooting tools. Pull one out and run the set. If it trips then put that one back and pull another. If it does not trip then start finding out what that relay services and continue troubleshooting the circuit that way.
ETN550 knows this stuff. Follow his directions carefully and he'll have you fixed up soon.
The relays are just electric switches that are actuated by something. You can use them to eliminate and/or identify which something you need to address.

 

derf

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I tried turning the relays around(K1 through K4) But it still won't run. I only had a problem with the control breaker tripping the one time, but thought that might be an indication that something else tripped because it happened right before I had the issue with it not running.

I took the fuel line off of the injector and there was no fuel in the line. There is no fuel in the filter either. There appears to be a fuel pump below the fuel filter mounted to the bottom frame rail. It only has one wire going to it I am assuming it is 24V + and it is grounded through the body of the pump. Is there a inline fuse or another breaker I should check ?

Now it appears you have an electrical (breaker tripping) and fuel (dry lines and filter) problem. So, either you have two issues going at the same time or maybe one issue with an electric fuel pump, if the unit has be retrofitted with a different motor.

Can you post a pic of your unit? It doesn't have a pull rope, does it? The fuel transfer pump on the Onan motor is mechanical. If you happen to have a Yanmar motor then it is a little different.

Sometimes when they sit the mechanical pump can get sticky. How long did your unit run since you got it? You may have an electrical problem and a sticky mechanical fuel transfer pump. Address the fuel problem first, then proceed to the electrical problem.
 
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ETN550

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I tried turning the relays around(K1 through K4) But it still won't run. I only had a problem with the control breaker tripping the one time, but thought that might be an indication that something else tripped because it happened right before I had the issue with it not running.

I took the fuel line off of the injector and there was no fuel in the line. There is no fuel in the filter either. There appears to be a fuel pump below the fuel filter mounted to the bottom frame rail. It only has one wire going to it I am assuming it is 24V + and it is grounded through the body of the pump. Is there a inline fuse or another breaker I should check ?

In that case you have an MEP-016E not "B". The "E" has the Yanmar engine which was a retrofit from the "B" with the Onan engine. They did not change the nameplate so it probably does say "B". The Yanmar has the red compression release on top of the head the Onan does not. It also has the pull start rope. In the case of the Yanmar there is no mechanical fuel pump. The pump below the filter is the primary pump from the on board tank through the filter to the injection pump. This pump should run all the time provided the float switches and relays in the tank are saying there is enough fuel in the tank. The other Aux pump is down by the fuel tank on the opposite side. The two pumps are identical. Try unplugging the primary pump under the filter, check its incoming connector for 24vdc with your meter with the switch on. If it does have the 24vdc on it then try switching out the pumps. Coincidentally, I had one of these pumps bad on an "E" and it was a brand new pump. Those pumps are available new around $90 - $120 and used around $50. Generally, they are not known to give trouble.

If you do not have 24vdc to the pump with the switch on then the problem is either the fuel level switch system or the pump feed.

Regarding the relays you can identify the pump relay in the control panel and you can feel the individual relays moving and hear them clicking if they get power. So if that relay is moving I would assume it is good. And you can interchange any of the relays for testing as they are all the same. Also, as noted before you can flip them over for a new set of contacts within a relay.

The float system is easy to check. With the tank empty or nearly so (easy to siphon out or drain on bottom) the lower float can be moved up and down with the switch on. This is the low fuel shut off float. Again, the relay can be felt and heard when the float position changes. The float switches are magnetic sealed reed switches and are very reliable. Sometines the float may be stuck if the gunk in the tank has caused it to be glued to the shaft. But there is a lot of clearance on the shaft and it is easily freed up.

The top float controls the other Aux pump down low on the right side. With the switch in the Aux fuel position cycling that float will cause the Aux pump and Aux relay to turn on and off.

It is not uncommon for the pumps to be stuck from sitting but since you have been running this is not too likely. However, they are easily serviced and cleaned up. (Always recommended) The bottom end caps unscrew and there is a filter screen and then a wire snap ring affair which when released allows the only moving part to come out. careful it is spring loaded! It is nothing but a solenoid plunger with some check valves in it. The plunger needs to move freely and the screen needs to be free of varnish. The pump can be bench tested by putting 24vdc to the one wire and grounding the body. It should pulse loudly with no fuel in it on the bench. My defective one quivered or vibrated only a little before it quit all together. The Aux pump is the one that usually is gummed up from sitting. Get it working and you will note how they pulse and the noise they make.

So first check that the pump relay is clicking and feel free to swap relays around. If okay then verify 24vdc at the main pump under the filter. If the relay is not getting power then the problem is between the master switch and the relay board. (Unlikely as the master switch controls all of the board at once)

When you do get the pump running open the bleed thumbscrew on top of the filter housing to let air out then close it.

If all this works as it should then the problem will may return later. If the round 24vdc breaker was bad or weak it would shutdown all functions.

See if any of this info helps you and report your findings or if you need more info. I have completely torn into these things many many times it is just a matter of isolating the components and systems until the problem is found. It never seems to be anything major.
 

Anthill

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It must be a Yanmar engine because it has the pull start. I will check the power to the pump.

It would have been much easier if they had marked the nameplate that it was an "E" not a "B". You must really be knowledgeable to be able to determine that it was an "E" with out even seeing it.

Thank you very much !
 

derf

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You gave clues that indicated that it might be a Yanmar.
If the lack of fuel was caused by the same problem as the tripping breaker then it had to be a Yanmar as the Onan has a mechanical lift pump. The Yanmar has an electric lift pump.
You'll probably find the 24V Facet electric fuel pump is dead. You can probably switch it with the aux fuel pump, I think they are the same but if you want to be able to draw fuel from an axillary source then you'll need both pumps working. It will need one to run and both to run and draw from aux source.

 

Anthill

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It has been a hectic couple of days, with 3 kids in baseball and first communion for two of them, but I finally got a chance to work on the generator.

The problem was with the electric fuel pump - I took your advice and swapped it with the aux pump and it works like a champ. With my luck this pump will go right when I need it, so I would like to get a new pump but I was unable to find any numbers on the pump - any idea where I can find a new one ?

Thank you very much for your help,

Ant
 

Isaac-1

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From time to time you can find them at very good prices on ebay, search on facet or purolator pumps (the model family is called Gold Flow), be aware the original mil spec model has a capacitor inline for noise filtering, it is not needed. Our 125KW Onan diesel generator at work uses this same model of 24V fuel pump, I was able to pick p a spare on ebay a while back for only $20 or so. in general 24V stuff is not as popular, and tends to sell at only a fraction of the price the 12V models go far.


Ike
 
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derf

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While this isn't the exact same thing it will function:

Edit, Removed active e-bay link...MOD
 
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Anthill

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I ordered a fuel pump from Ebay.

Are spare fuses for the outlet available as well ? I blew one with my grinder and another with my air compressor.

Thanks,

Ant
 

ETN550

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Standard fuses will work. I would use a slow blow style. I think 10 or 12 amp is the rating.

Regarding those outlets on the front. The outlets are intended for light use only and not to draw a big load. The front outlets are always active. The front outlets are directly connected to one of the three power coils inside the generator. Pulling a lot of power off of one coil causes an electrical imbalance. And since the remaining two coils are doing nothing the amount of power available is limited thus the fuse to protect. Use the front outlet for testing or a trouble light or other small load only.

The main load is to come off of the brass lugs behind the clear plastic hinged cover behind the control box on the right side. The single phase 120 mode is the most useful. Set the switch inside the control box to 120 single phase. Go to Home Depot or Lowes and buy some 10 gage 3 wire "SO" cord (SO is like a thick flexible extension cord) and a few outlets to make up a metal quad box. Then wire up the two hot leads of the new quad box to L1 and L2 on the lugs and ground the other lead to the brass ground lug on the bottom of the skid frame below the control box. Then you can pull the full load off of your quad box outlets and you will see what she is really made of! It will easily pull 3 to 4 times the load that blew the outlet fuse. Enjoy! Glad you identified the fuel pump as your problem and already ordered a replacement.

(This pic shows a 10 gage SO cord hooked up to the lugs where the main power comes out) Note this one is a 016B, as the top of the engine looks different from your "E" but the electrical generator part is identical.

DSCN3201.jpg
 
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Speddmon

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Ike and Derf,

I know you guys were just trying to help out, but we can't post active e-bay links per the rules
 
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