Fuel Pumps and Fittings MEP-803a

So, I have bought 3 fuel pumps and despite the listing's part numbers or pictures, all 3 of them are auxiliary fuel pumps; not primary pumps. I need the primary pump replaced. The big difference is the input and output fitting sizes. I don't know exactly what they are but the original pump seems to have -5 AN x 3/8" NPT fittings and the aux pumps have what looks like 1/4" NPT threads. I am trying to find out what exact fittings I can use to adapt the aux pump to the -5 AN primary fuel lines. Do I need a -5 AN x 1/4" NPT fitting on both ends or is it some other size?

What pumps did you buy? Got a part number and manufacturer name?

Facet 41116

NSN 2910-01-378-6025

According to the fleabay ad.

I will check the number on the unit when I get home tonight.

This is what I received.

https://www.amazon.com/FACET-SOLID-5-6-5PSI-CARBURETED-ENGINES/dp/B013SGG7GI

eatont9999 said:

This is what I received.

https://www.amazon.com/FACET-SOLID-5-6-5PSI-CARBURETED-ENGINES/dp/B013SGG7GI

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Make sure it works before installing. Those are bad about being bad from the start. I know several members that have purchased them and have been dead on arrival.

I haven't compared to the one on mine but do you think the Spectra SP1174 pump would work?

Beware of Chi-Com knock-offs. A few years back walbro started selling to the public trying to save their good name

csheath said:

I haven't compared to the one on mine but do you think the Spectra SP1174 pump would work?

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It might work. I bought a Spectra radiator some years ago and it is still running strong, so I am familiar with the brand and quality. The price is right, too. I'm half tempted to just swap out these AN fittings with hose barbs to make it easier to work on. AN fittings are expensive and not easy to come by at the drop of a hat - at least not out here in the country.

There are also mechanical fuel pumps available for the LPW series engines. Any thoughts on those?

eatont9999 said:

It might work. I bought a Spectra radiator some years ago and it is still running strong, so I am familiar with the brand and quality. The price is right, too. I'm half tempted to just swap out these AN fittings with hose barbs to make it easier to work on. AN fittings are expensive and not easy to come by at the drop of a hat - at least not out here in the country.

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The parts manual shows both fittings are pipe to tube and the Spectra pump indicates the fittings are 3/8 so I bet it's got 3/8 NPT threads for hose barbs. The stock fittings may screw right into it. I found the pump listed at Autozone as well as online so if you have an Autozone local you could probably return it if it won't work.

EDIT: I just looked at the primary pump on my 803 and it is a tiny round pump with 1/8" NPT fittings on the pump. I have a similar size 12V pump I use to transfer fluids and it also has 1/8" NPT threads. The size of the Spectra pump may require some modification in the space or removal of the perforated shield guard but the fittings should be able to be bushed and adapted.

The proper fittings to use an auxiliary fuel pump as the main fuel pump are as follows.

1/8" NPT x 1/4" JIC

I ordered several fittings, tested them out last night and they fit the pump and hose connections. Now I can use the 3 aux pumps I have for either application.

The fitting size is not the only difference in the main vs aux pump. The output gpm and pressure are both different. Will an easier to find aux pump work for the main? I dont know...im still trying to figure this out.

Finally located the test procedure in the TM. Seems they called it a transfer pump in that manual instead of primary fuel pump. It doesn't give a pressure specification but says it should have a minimum flow of 25 ounces in 1 minute. that equates to 11.7 GPH.

My genset doesn't have any problems and has the Airtex pump so I may measure the pressure and volume on it one day just for reference.

I found another Spectra pump that looks like a better match than the one I linked to above. The SP8123 looks a lot like the Airtex pump on my 803.

I also found another Airtex number E11010 listed for an Onan Generator that has about the same specs as the Spectra above but for some reason Airtex doesn't tell you the voltage on it.

Today happened to be my schedule load test day so I performed a fuel pressure and volume test on the Airtex E1074 installed on my unit.

Fuel test
08/13/2017
Dead head pressure was 6 PSI
Volume was ¼ gal in 60 seconds = 32 ounces per min = 15 GPH

Thank you for testing and posting your findings with the pump.
With your findings i would think the 6-8psi and 35gph airtex E8135 should work fine for the primary pump. It is 3/8 fittings and not 1/8in

Bmxenbrett said:

Thank you for testing and posting your findings with the pump.
With your findings i would think the 6-8psi and 35gph airtex E8135 should work fine for the primary pump. It is 3/8 fittings and not 1/8in

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I think that 3/8" is the hose barb diameter, not the pipe thread size. The threads are probably 1/4" or 1/8" NPT like most of these type pumps I've seen. Also the Airtex E8135 is a straight through pump that will most likely result in the need to trim or remove the perforated shield above it.

The Spectra SP8123 or the Airtex E11010 look like they would fit right in the space like pictured on mine. Not sure if the E11010 is 24 volts as Airtex doesn't list voltages in their specs. (go figure)

The very first generation MAIN fuel pump for the MEP-802A and MEP-803A was the 2910-01-378-6025, Army part number 40193 or 88-20192, FACET part number 40193. Here are the characteristics:

csheath said:

The Spectra SP8123 or the Airtex E11010 look like they would fit right in the space like pictured on mine. Not sure if the E11010 is 24 volts as Airtex doesn't list voltages in their specs. (go figure)

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Called AirTex technical support. The E11010 is 12V, but they do have two 24V pumps:

E8131 10-14 psi
E8135 5.5-9 psi

Both are in the 14 gph free-flow volume range. AirTex sells on Amazon.

-- Carl

Hi, My mep803A is a 2006 that had 15 original hours on it when I won it. As far as I can see it has never had any parts replaced. I have the rear panel off to troubleshoot fuel sensor problems and the auxiliary fuel pump and primary fuel pump both have the same numbers E1074.

dav5 said:

Hi, My mep803A is a 2006 that had 15 original hours on it when I won it. As far as I can see it has never had any parts replaced. I have the rear panel off to troubleshoot fuel sensor problems and the auxiliary fuel pump and primary fuel pump both have the same numbers E1074.

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That's the front of the set. The rear is always where the control panel is.

It would appear that someone could not get right pump, or wasn't paying attention to what they were doing. Or, it was time to close the work order on the set, and " it's close enough for government work" crossed someone's mind.