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MEP-804A/B fuel float switch replacement - non-existent??

S

ssybert

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Hello everyone,

I have an MEP-804B I'm resurrecting which has a bad lower float switch indicating and preventing startup from a permanent 'no fuel' situation. Mine is a Madisson M3465, NSN 2910-01-376-2268. There are other manufacturers for this part but an exhaustive search of the internet turns up absolutely nothing. I can't' be the only person with a bad float switch in an MEP-804. What are others doing for a replacement part here? I'm about ready to measure and order a custom switch from Liquid Level but would prefer an OEM solution.

Thanks for any leads you may have,

Scott
 
R

Ray70

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"Custom" sounds pricy! What are you looking at for 1 custom sensor?
There's gotta be a better solution out there.
Have you exhausted all associated PN's? I assume yes. By this I mean that when searching by NSN number you can often find other OEM PN's associated with that NSN number. Those PN's tend to yield better search results than NSN's
Also wondering if you tried this thread for info? It contains those "other PN's"

Civilian Equivalent of MEP804A-B Fuel Level Switch NSN 2910-01-376-2268, 88-21121, 134230, M3465, 10455-1

Does anyone have the Ohm range for the fuel level switch on the MEP804A-B? Looks like 24v and 8 inches would do, but not sure of the Ohm range. These are the details I have: ACYR DC Voltage Rating 24.0 volts nominal ADAV Overall Diameter 1.250 inches nominal AFLW Actuation Method Buoyancy...
www.steelsoldiers.com
 
S

ssybert

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Chelmsford, MA
Ray70 said:
"Custom" sounds pricy! What are you looking at for 1 custom sensor?
There's gotta be a better solution out there.
Have you exhausted all associated PN's? I assume yes. By this I mean that when searching by NSN number you can often find other OEM PN's associated with that NSN number. Those PN's tend to yield better search results than NSN's
Also wondering if you tried this thread for info? It contains those "other PN's"

Civilian Equivalent of MEP804A-B Fuel Level Switch NSN 2910-01-376-2268, 88-21121, 134230, M3465, 10455-1

Does anyone have the Ohm range for the fuel level switch on the MEP804A-B? Looks like 24v and 8 inches would do, but not sure of the Ohm range. These are the details I have: ACYR DC Voltage Rating 24.0 volts nominal ADAV Overall Diameter 1.250 inches nominal AFLW Actuation Method Buoyancy...
www.steelsoldiers.com
Click to expand...

OP in that threat is looking for info on the same P/N I'm looking for however the folks replying are referring to the fuel level sending unit. These sets have two float systems. One is fuel sending unit, operating on a standard 240-33 ohm to indicate fuel level. The other is a dual float system which contains two floats that slide up and down on a single, round, sealed tube. The top float is positioned to slide between 1/2 and 3/4 of a tank and controls the AUX fuel system. the lower float is positioned at the bottom and will open a circuit if the float falls to about 1/8" to the bottom of the tank. Both of these switches are N/C and open when they bottom out. No impedance measuring, just continuity.

I've searched all P/Ns and the NSN... Everything that comes up is just a place to get a quote, presumably for a special order of 1000 pieces, lol. I did find one seller that has some aftermarket pieces but he's sold out.

The last custom dual float I ordered was ~175.00 but it was plastic and back in 2020. I'd go stainless on this one so I'm guessing somewhere in the low to mid $200s??
 
S

ssybert

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Light in the Dark said:
KUS/WEMA it appears may make a civilian equivalent, just needs someone to discern from their marketing data what the right one is

https://www.ebay.com/itm/254333646541 (it sold a few weeks ago, but is listed as a civilian equivalent)
Click to expand...
That was the seller I mentioned but didn't think to look at who the manufacturer was in the listing! Good catch! I'll measure mine and do some digging this afternoon. Hopefully they have an off-the-shelf replacement and it wasn't a custom run. If I find match, I'll post it. Thanks for the assist, LitD.
 
2

2Pbfeet

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Mt. Hamilton, CA
Light in the Dark said:
KUS/WEMA it appears may make a civilian equivalent, just needs someone to discern from their marketing data what the right one is

https://www.ebay.com/itm/254333646541 (it sold a few weeks ago, but is listed as a civilian equivalent)
Click to expand...
@ssybert Are there any visible part numbers on your float switch?

As @Light in the Dark wrote, WEMA is probably the source for the original switch. Globally, they make most of this type of switch, and are the go to manufacturer for many customers. The WEMA level sensors are very common and some models do exactly as you describe. There are many resellers, and even some clones, but I would stick to WEMA, as they make a high quality unit. Buying directly from WEMA often gets you a few more options for the preset levels. Just make sure that the replacement isn't too long, as you want some clearance under the bottom to ensure it won't vibrate against the tank and wear a hole in the tank.

All the best,

2Pbfeet
 
Light in the Dark

Light in the Dark

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Madison is the OEM, same as the 802/803.... Just different design. Custom for these applications. Last VOLUME price I got on 802 double float switches was $225 ea plus freight. That was either 50 or 100 at a time!
 
2

2Pbfeet

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Mt. Hamilton, CA
Light in the Dark said:
Madison is the OEM, same as the 802/803.... Just different design. Custom for these applications. Last VOLUME price I got on 802 double float switches was $225 ea plus freight. That was either 50 or 100 at a time!
Click to expand...
Business opportunity there? Ever had one apart? They are pretty simple inside, but I think that the secret sauce is being able to assemble them in a way that results in reliable long term performance. The technology is both old and simple, and I think that the simplicity makes it fairly reliable. IIRC: the reed switches were available in an inert gas with a special glass version to maximize longevity, but that made the switches rather pricey...

All the best,

2Pbfeet
 
Guyfang

Guyfang

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The reed switches have always been made that way. Back before the Mil-Stan gen sets, they were not in the gas/gas package. They were highly unreliable. The floats were a problem for a long time. The magnets fell out. Or when fuel pumps went bad, a fine metal "power" coated the floats/magnets, causing the float to fail. JP8, ate the floats up. All you would find in the fuel tanks/day tanks were the magnets. Back in the late 70's early 80's when the switches were very hard to get, we saved then and then tried to make one out of 3-4. Yes, you can get the reed switches out of the plain straight type switches. They did not use toooooo much RTV, and if you had long hours on a rocket site, and luck, you could "repair" a float switch.

I found five part numbers, two of which are of no help as there are CECOM number. Made up numbers. And three suppliers to the government.
 
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Light in the Dark

Light in the Dark

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I'm going on what... 5 years? of sitting on hose assemblies for 80X machines. I've got dozens of sets of sheet metal here too. Incremental $ for what has to be laid out to get anything made.

Hopefully someone can find stock crosses, or at least something that can be modified to work.
 
B

Botl01

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I have the same issue. My low fuel light came on last week. Green mountain shows out for stock for P/N 88-20481.

Has anyone tried using the WEMA KUS SSS 5.5" Fuel sender as a replacement for the Switch, liquid level. I don't use an aux fuel tank so I don't need the extra float.
 
K

kloppk

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You can't use that to replace the float switch.
The Low Fuel float switch is a "switch". ON-OFF
The WEMA KUS SSS 5.5 is a variable resistance unit for sensing fuel level. 240 ohms to 33 ohms.
 
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G

grywitt

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I've had a similar problem. I had the guys at liquid level build me one that I haven't installed yet but it has two floats and the top float instead of having 3 inches of travel before changing state has about 3/4" so the aux pump will run more often. I paid $145 for the float. I don't mind sharing the quote number which is 10214 and the guy I worked with is Pete at liquidlevel.com and the number is 800 789 2851. If you see any flaw in my design I would like to know it. I thought I had fixed my original float and just last night I realized the problem is back. I guess I'll probably be using the alternate after all. I've attached a copy of the design but page two had the quote number but also my address payment info ect so I dropped that. I should be able to use the flange on the origonal float to mount this.
 

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