MEP-003a fuel pump question

[lxawolf]

Working over the last few weeks on a new to me MEP-003a I have gotten a lot done. I have replaced the oil, oil filter, cleaned out the fuel tank, replaced the fuel filters. New battery cables and batteries. Before I did any work on the fuel system I turned the the starter switch to both prime and run positions. Before the work they would click and start out faster then slow as the system comes up to pressure. (As seen in multiple YouTube videos) Now after changing both fuel filters inspecting the strainer, and checking the pump internal filters (aka open the port at the bottom of the fuel pump) the auxiliary fuel source pump clicks but not nearly as fast. Both the primary pump and the return line pump are making no sound or moving any fuel. I took off the fuel line going to the injector pump thinking I might have an air lock but even doing that did not change the outcome.

I took off the rubber gasket on the power supply wire, I am getting 24v at the connection. I also removed and replaced the two rusty bolts with two new bolts holding the pump to the frame thinking that I was not getting proper grounding.

Could I have damaged something just by checking the internal pump filter? I did not use excessive pressure to remove the base, or to put it back on.

Has any one else had a similar experience? Do I need to get a new pump? What can any one recommend trying or doing that I am missing?

Thank you for your help ahead of time!!!

 

[Isaac-1]

I have never seen that before, but just a couple of things, you did put the magnets back in the end caps? Also before giving up on these pumps be aware the inline RF filter capacitors are a common failure point, they really are not needed unless you are using the generators to power radio equipment, the civilian version of these pumps don't even have them. I would also suggest checking (loosen wiggle, re-tighten) all your main component assembly ground straps, particularly the one to the control box.

 

[lxawolf]

I did not know they were magnates in the end cap, but i did not move them I just cleaned around them. I will check the inline capacitor. I did not think to check them. I checked the voltage at the rubber connection where the white fabric wire entered the black rubber / pvc coated wire starts. not at the end where it conects to the actual pump. Looking at the pump body it looks like it has a crimp or screw connector onto the pump body. Are you able to take the wire lead off the pump body and check for voltage there?

 

[Isaac-1]

I am not sure, I have never had one with a bad capacitor myself, just read about plenty of examples. Since it happened to all 3 pumps I think it is more likely a grounding problem going back to the control box.

 

[Chainbreaker]

If I am reading this right you are saying that the Aux fuel pump is still working but the 2 primary fuel pumps no longer work after servicing them. What happens if you switch the lead at the rubber connectors coming out of the harness with the Auxiliary one connected to one of the Primary pumps temporarily and then try (Prime/Run Aux). Does that pump now prime? Although I think you indicated you are getting 24V at all 3 (?) connectors so this may be a moot exercise. Would seem strange that 2 capacitors would fail simultaneously on 2 of 3 pumps when they were working prior to servicing. So another vote for Grounding as a likely issue if all three pump leads are confirmed to have 24v when priming.

Another thought - did you ever verify before this issue came up, that the return fuel line was trickling fuel back to the tank (you can hear it with fuel cap off) and your tank vent cap is set to open?

 

[rustystud]

Both Isaac and Chainbreaker bring up good points. I have accidently reinstalled the wires to the pumps in the wrong order. I have also had the inline capacitor just fail for no reason ! Since then, I have colored coded my pump wires with colored Ty-wraps, and removed all the inline capacitors. I have also replaced all my fuel lines as the old ones where breaking down. You cannot see if the inner lining has come loose and is blocking the fuel.

 

[cuad4u]

The 002A and 003A generators consist of several modules, each of which must be grounded to the other ones. This is done either through mounting hardware or separate ground straps or both. I have had several of these generators that have bad ground connections between modules. In at least two of them the fuel pumps would not run. Just running a ground wire from the battery (-) terminal to the chassis where the fuel pumps are mounted will tell you if the fuel pumps are grounded or not. I bet as soon as you run the ground wire from the battery (-) to the fuel pump mounting bracket the pumps will run. Been there done that! If so clean the ground connections.

 

[lxawolf]

I do not recall if the fuel was returning to the tank. It's very possible the fuel never returned properly in the first place. A new set of fuel lines are on the list to get replaced. I have been checking around to local hydraulic shops in my area. Most charge by the foot and a charge for the installation of the fittings. Looks around a dollar a foot. Does this sound like something others have charged in the past? I have not had a chance to try a jumper to the negative lead to the battery. But that does sound good to try. No need to buy expensive parts if not needed. I will try that this week and hope to update soon. Once again thank you for the information and advice.

 

[dangier]

You can go the hydraulic shop route, but you do not need to. The fuel and oil cooler lines are made to be replaceable in the field by the military. It took me a while to figure it out, but the end fittings do come apart and are reusable. If you can find a flare fitting that will screw into the hose end, and tighten up good, you can hold the collar with a wrench, the center end connection will unscrew. Then the collar will come off the hose with left hand threads. That way you can just buy the hose stock and make your own hoses at home. I don't have the hose information right now, but you do not need the heavy duty stuff. The local hydraulics ship might be able to help you order light duty (two wire or less) hose. One of my customers did not want the expensive hose and I used the existing ends with 25 psi auto fuel hose and screw clamps. Works as the fuel pump pressure is around 8 psi. Not my choice though.
David

 

[rustystud]

You can go the hydraulic shop route, but you do not need to. The fuel and oil cooler lines are made to be replaceable in the field by the military. It took me a while to figure it out, but the end fittings do come apart and are reusable. If you can find a flare fitting that will screw into the hose end, and tighten up good, you can hold the collar with a wrench, the center end connection will unscrew. Then the collar will come off the hose with left hand threads. That way you can just buy the hose stock and make your own hoses at home. I don't have the hose information right now, but you do not need the heavy duty stuff. The local hydraulics ship might be able to help you order light duty (two wire or less) hose. One of my customers did not want the expensive hose and I used the existing ends with 25 psi auto fuel hose and screw clamps. Works as the fuel pump pressure is around 8 psi. Not my choice though.
David

A lot of the military fittings are the repairable type, but I have found they usually are really rusted up especially ones used with diesel fuel. That's why I went with the brass fittings and nylon hose on mine.

 

[lxawolf]

To give a quick update, looks like I am now going to need new pumps. I took off the control wires and jumped them directly to the battery. I had no change in function. A disappointment but glad they are being replaced now not out when needing them. I am inclined to agree with Rusty. A lot of the fittings are slightly rusty and and a lot of the steal elbow connectors are very rusty, I probably could clean them up with work but who knows the condition of the them. When it comes to the family I would spend the few dollars and make sure its done right the first time.

One other question I have is the thread into the current military pumps. Is it a AN thread or a NPT thread (when I say threads, I am talking about the female threads inside the actual pump body, not any elbow connectors) ? I know the lines themselves are AN -5. I ask because I found a place that has 24v pump with output of 1/4 NPT thread. I know its easy to find adapters.

Also to the ones who have replaced lines and connectors. Did stay with AN fittings or did you switch to JIC, NPT, or go with something else? I want to go to the spin on fuel filter kit and was not sure if it was easiest to stay with AN or go another route.

 

[Munchies]

The fittings are MALE NPT on the the pump and the 90* fitting is npt female x AN

 

[rustystud]

To give a quick update, looks like I am now going to need new pumps. I took off the control wires and jumped them directly to the battery. I had no change in function. A disappointment but glad they are being replaced now not out when needing them. I am inclined to agree with Rusty. A lot of the fittings are slightly rusty and and a lot of the steal elbow connectors are very rusty, I probably could clean them up with work but who knows the condition of the them. When it comes to the family I would spend the few dollars and make sure its done right the first time.

One other question I have is the thread into the current military pumps. Is it a AN thread or a NPT thread (when I say threads, I am talking about the female threads inside the actual pump body, not any elbow connectors) ? I know the lines themselves are AN -5. I ask because I found a place that has 24v pump with output of 1/4 NPT thread. I know its easy to find adapters.

Also to the ones who have replaced lines and connectors. Did stay with AN fittings or did you switch to JIC, NPT, or go with something else? I want to go to the spin on fuel filter kit and was not sure if it was easiest to stay with AN or go another route.

Here's some pictures of how I did mine. I used the Nylon air/fuel rated hose and brass connections with ferrules and tube inserts. Works great. No leaks in over 3 years now.

 

[Harleyd315]

I use push lok hose and fittings to replace any old lines I change.

 

[rustystud]

I use push lok hose and fittings to replace any old lines I change.

I would have liked to have used them too, but there twice the money of what I spent on the regular fittings.

 

[lxawolf]

IT LIVES!!! I got a new pump in the mail yesterday, I ordered two but only installed one. I turned to prime and run let it prime for a while, and it started up after about 15 seconds of cranking. A huge thank you once again to everyone here who helped bring this great generator back to life!

Because I did order the two pumps, I take it does it need the two redundant pumps. Do I keep it for some reason, return it, or put it on in the same second pump position?

 

[Isaac-1]

The second pump is a redundant safety factor, it lets the generator keep running if one of the electric pumps dies

 

[rustystud]

The second pump is a redundant safety factor, it lets the generator keep running if one of the electric pumps dies

Just as Isaac said. You know the military " two are one and one is none" .

 

[RJM27]

Where did you get your pumps, model & parts # looks like I'm in the same boat. How much were they if you don't mind me asking? Thanks!

 

[Harleyd315]

If I'm not mistaken Rock Auto has a 24V replacement pump. Airtex E8131 that I have used. Not OEM but a cheap alternative. You will need to change some hose and fittings and it is suggested to use an inline filter before the pumps. Aircraft Spruce also has Facet pumps that will work.