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Mep-802a aux fuel pump trips breaker?

loosegravel

loosegravel

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Just thinking out load here. The wheels are turning! Unlike the fuel gauge sending unit which is basically just a variable resistor, the dual float the we’re talking about in this thread I believe is more of an on/off switch for two different purposes. One float I believe is to activate the low fuel fault which will shut the unit down if activated, and the other float I believe is to turn on/off the auxiliary fuel pump. I’m thinking that we could omit the low fuel shutdown and just try to come up with one switch that will turn on/off the auxiliary fuel pump at the correct fuel level. I mean even if the unit doesn’t shutdown for low fuel, the worst outcome from that is the need to refill the tank and prime the fuel system. On the 802’s and the 803’s that only entails turning the S1 to prime/run and let it prime itself. Am I way out in left field?
 
Guyfang

Guyfang

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I like the low fuel cut off switch. There are times, like when it O-Dark thirty, raining or the air temp is a million degrees below zero, and the darn thing will not prime itself. If it runs dry, or turns off before it runs dry, you still have to refuel it.
 
loosegravel

loosegravel

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Guyfang said:
I like the low fuel cut off switch. There are times, like when it O-Dark thirty, raining or the air temp is a million degrees below zero, and the darn thing will not prime itself. If it runs dry, or turns off before it runs dry, you still have to refuel it.
Click to expand...
I know that it does serve a purpose. My wheels were just turning, trying to come up with a simple solution if the dual float switches are either no longer available, or they’re just way over priced. I was trying to prioritize the low fuel shutdown versus the auxiliary fuel pump operation. I wonder if we could use one switch to control both?
 
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kloppk

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I've been thinking about this one. It strange they used three different fuel level measuring systems, one for the gauge, a second for Aux Fuel and a third for Low Fuel. A single level sensor with a tiny bit of smarts could accomplish all three functions.
The MEP-10xx sets use a single ultrasonic level sensor for all three functions. The 10xx DCS has the smarts to do all three functions from the single sensor.
Maybe for the 80x units use a KUS sensor in place of the factory fuel level sensor with a bit of smarts to do all three functions.
The KUS sensor to eliminate the mechanical VR wiper and wire in the factory fuel level sensor.
 
Last edited:
loosegravel

loosegravel

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kloppk said:
I've been thinking about this one. It strange they used three different fuel level measuring systems, one for the gauge, a second for Aux Fuel and a third for Low Fuel. A single level sensor with a tiny bit of smarts could accomplish all three functions.
The MEP-10xx sets use a single ultrasonic level sensor for all three functions. The 10xx DCS has the smarts to do all three functions from the single sensor.
Maybe for the 80x units use a KUS sensor in place of the factory fuel level sensor with a bit of smarts to do all three functions.
Click to expand...
Sounds reasonable! Is the MEP-10xx series unit a single float on a rod with (3) different docking points? I would think that the fuel gauge would still require a variable resistance while the low fuel shutdown and the auxiliary pump would be fine with an on/off setup.
 
loosegravel

loosegravel

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kloppk said:
The 10xx use a high tech ultrasonic level measuring technique to determine the fuel level with no moving parts. It outputs a DC voltage proportional to the fuel level.
Click to expand...
Interesting. I’ve never seen such a level sensor that can operate a full range gauge. I’ve seen many different kinds level switches though that can turn on and off indicator lights etc. That is high tech.
 
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kloppk

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loosegravel said:
Interesting. I’ve never seen such a level sensor that can operate a full range gauge. I’ve seen many different kinds level switches though that can turn on and off indicator lights etc. That is high tech.
Click to expand...
The DCS in the MEP-10xx reads the DC voltage from the sensor and then displays the fuel level on it's LCD display panel.
Here is a 1030 Fuel Level Sensor. No floats, just a tube.
MEP-1030 Fuel Level Sensor.jpg
 
Guyfang

Guyfang

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Lets not forget that when this switch was brought from drawing board to reality, it has been a few years.

The switch Kurt displayed, is about the only kind I have seen here in Germany, for at least the last 10-15 years. We installed them in houses that are in danger of flooding. No one will insure you, unless you have a sump, in the lowest part of your basement, with a stitch to turn on a:

1. Audible signal.
2. Turn on a a loud freaking horn.
3. At a another trip point, turn on a pump.
4. Alert the Fire Department, after another trip point, if the system is not manually reset.

Kurt, I think J.I. Joe has sent me a picture a while back, where he found a new type float, and installed it on a MEP-802A? Hit him up and ask.
 
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ribs1

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Ok,
Looks like I'm back to the drawing board. I installed new dual float switch and now I have a new problem. It's not tripping the breaker anymore. When set to prime and run, it stops after a few seconds. When I set it to start, it turns over, does not start than is unresponsive. If I set it back to off, then try again, same thing. If I unplug the float switch, everything works as normal.
 
DieselAddict

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If you are getting a low fuel lockout but no low fuel light, you may have an issue with the alarm panel.
 
Guyfang

Guyfang

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Hardly possible. How much fuel in the tank? Are you sure you hooked up the float switch right? Is it a original military part? or something civilian?
 
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