MEP-002A, will Start, Run then dies....any suggestions?

[Chainbreaker]

Let me see if I can put my 25 cents in,

Each Fuel Pump has a Capacitor for EMC suppression. They have the nasty habit to fail shorted or with very low resistance. They fail intermittently over time, barely ever completely at once.
We may just have one or two failing caps on the two fuel pumps for run.
Failing Capacitors also can work for a few seconds or minutes and then their internal resistance decreases and this will reduce the current available to the fuel pump, slowing fuel pump down until fuel pump stops all together.

Disconnect capacitors and see if this fixes the problem.

Note to the Innocent bystander,
Back in days when we had TV's with picture tubes and the vertical picture stabilizer capacitor went bad, then the picture would become vertically smaller over time like in the old movie films and finally you would see only a long bright stripe across the screen in the center.

So by "disconnect capacitors", I assume you mean cut them out and splice with butt connectors? That would seem to be the best fix given most of us aren't concerned with EMI.

 

[Scoobyshep]

@Scoobyshep , I am sure gald you didn't become a TV Repair Man! This would have been the Cap for the Horizontal Stabilizer, which failed completely open....

I think I'll stick with the electrician\controls engineering route, ride systems can be annoying enough yet gratifying

 

[rickf]

Let's see, video gams on CRT TV's. That would be pong or maybe Pac-man.

 

[Scoobyshep]

Let's see, video gams on CRT TV's. That would be pong or maybe Pac-man.

It was a Sega Genesis, I was playing Sonic the hedgehog 2. It was an old console TV that was around before I was, it took 3 guys to haul it out of the basement to get it repaired, the shop fixed it inside a week and that thing stuck around until 2003.

 

[peapvp]

So by "disconnect capacitors", I assume you mean cut them out and splice with butt connectors? That would seem to be the best fix given most of us aren't concerned with EMI.

Yes, as they are soldered. You could desolder the cap as well.

 

[Guyfang]

You could also disconnect one pump. Run the set for a few hours. Then reverse the process. Simply disconnect the first pump. and hook the second pump up. Run it a good long while. And with a load if possible.

 

[Chainbreaker]

You could also disconnect one pump. Run the set for a few hours. Then reverse the process. Simply disconnect the first pump. and hook the second pump up. Run it a good long while. And with a load if possible.

One could install a couple of toggle switches to accomplish that. There are 24 VDC round toggle switches that could be mounted in frame example. You could then toggle on just one, or the other, or both if you're running in "mission critical mode" (redundancy factor if one fails). There are some lighted ones when turned on that are also available, so you could easily visually verify which pump is energized.

 

[1FAST4]

Thanks All! I still haven't had the opportunity to do anymore of the troubleshooting that you all have suggested but I will hopefully get into to it by the end of this week and report back. Your input/suggestion is very helpful and greatly appreciated... Please keep it coming.

 

[1FAST4]

Ok guys I'm back...Spent most of today going through of the troubleshooting steps you all have suggested and here's where I'm at thus far:

1. Tried to start the Gen Set thinking maybe the issue had somehow self-corrected (I know, wishful thinking and you're right). It started, ran for about a minute, slowed then dies. So, then I started getting into the fuel system.

2. Removed fuel line elbows, after fuel filters, and check valve for cleaning. Check valve seemed to have a slight sticky feel when the plunger was pushed but no obvious gumminess. All now soaking in Acetone, so we'll see.

3. Checked the PSI on the main pumps; "P1" and "P2" ; Connected pressure gauge to the outlet of P1, disconnected power to P2, turned the Master Switch to Prime and P1 held at 7 PSI. Connected gauge to outlet of P2, disconnected power to P1, turned the Master Switch to Prime and P2 held at 4 PSI. Leaving the gauge connected to P2's outlet I reconnected power to P1, turned the Master Switch to Prime and with both P1 and P2 running the gauge showed 10+ PSI. So, here is the question: Is the (low) 4 PSI shown on P2 a result of it working harder because it has to pull fuel through P1 when P1's power is disconnected or is there an issue with the pump itself?

4. Removed, Disassembled and cleaned all 3 fuel pumps. P1 and P2 were pretty dirty in the lower chambers and strainers . The Aux pump looked very clean but did have some dirty (old) fuel in the upper chamber; I have never used the Aux Pump. I also noticed the top of the plungers from the 3 pumps all look a bit different; is this normal? . The bodies, plungers and springs are currently soaking in Acetone. I wasn't sure if the plastic ball valves, O-rings and strainers where Acetone safe, so I left them out of the soak.

5. Fuel Tank Drained, Removed and is currently soaking in Acetone. The inside of the tank didn't look any worse than when I clean it when I first got it....A little more rust on the filler neck strainer but that about all I see at this point.

Again, any thoughts, suggestions and/or input is greatly appreciated.

 

[Chainbreaker]

Good job on the pumps! If you still have the pumps off, I would strongly suggest you eliminate, cut out, the capacitors, butt splice or solder & heat shrink insulation. They are not needed in Civilian operation and are a potential failure point since they are very old.

Also, what about the upstream fuel filters... recently serviced?

 

[1FAST4]

Good job on the pumps! If you still have the pumps off, I would strongly suggest you eliminate, cut out, the capacitors, butt splice or solder & heat shrink insulation. They are not needed in Civilian operation and are a potential failure point since they are very old.

Also, what about the upstream fuel filters... recently serviced?

I will remove all 3 EMC capacitors once I get the pumps all cleaned and put back together...Thanks, that was going to be one of my follow up questions. The upstream Wix filters have only 9 hours on them but plan to put fresh ones on anyways...just is case.

Any thoughts on the one pump thats only putting out 4 PSI?

 

[Ray70]

Can't say that I have ever seen a plunger like #2 there.... the 3 pumps are all normally identical, not sure what the piece is in the top of plunger #2.
If you remove it, does the spring under it look identical to the others?
You really don't need both of the primary pumps, you could try testing with just the 1 10PSI pump, bypassing the other and see if it has any improvement.
Or swap the Aux. pump with #2, if you don't intend to use the Aux. fuel circuit.

 

[rickf]

I would run your pressure tests again once you get them cleaned and back together. I have also not seen that type of plunger, looks like a seal of some sort. If I had to guess I would say it may have been replaced and the replacement was from a different contract and different company. As far as swapping the low pressure pump with the aux pump I would hold off on that just in case you do want to hook up that auxiliary tank some day. That pump will be working harder since it has to draw from a lower tank and therefor has to pull a suction. You will want the stronger pump there. On the other hand, you could replace the aux with a different inline pump for that function since pressure is not a concern, it is only moving fuel from a large tank to the day tank. You just need to make sure the electrical draw is the same or less. What is the pressure spec for the lift pump? I know it is not very high since all you are doing is moving volume and not depending on high pressure.

 

[Scoobyshep]

I would test for flow as well. Pressure is just part of the equation.

 

[Scoobyshep]

I found these specs on line for the fuel pump.

Maximum fuel delivery 33 gallons per hour at free flow. Maximum pressure 6 to 8 psi. Typical flow 15 gph @ 2 psi. 1/4 NPT male fittings. Features a built-in EMI filter to minimize radio interference. This pump includes an internal 74 micron filter. Reliable solid-state construction means no points to burn out.

 

[Scoobyshep]

Might be worth checking feed through. the pumps were designed to allow 1 to fail and still deliver fuel. There is a similar model that doesnt allow this and a bad pump will stall the engine.

 

[Scoobyshep]

Another silly stupid thing, Check the tank cap vent.

 

[Guyfang]

Might be worth checking feed through. the pumps were designed to allow 1 to fail and still deliver fuel. There is a similar model that doesnt allow this and a bad pump will stall the engine.


This is why I asked if all the pumps are the right pumps. The manufacturer makes many pumps that LOOK like the right pump. But they do not feed through.

 

[1FAST4]

Might be worth checking feed through. the pumps were designed to allow 1 to fail and still deliver fuel. There is a similar model that doesnt allow this and a bad pump will stall the engine.


This is why I asked if all the pumps are the right pumps. The manufacturer makes many pumps that LOOK like the right pump. But they do not feed through.

Here are the numbers I found on all 3 pumps while cleaning, . I'm pretty sure there're the correct pumps (w/Feed Through) because when I did the pressure test on P2 (4 PSI) I did NOT connect the fuel supply directly to the inlet; I left both P1 & P2's fuel lines connected in series while testing...the fuel inlet hose of P2 was connected to the outlet of P1 and P1's inlet was connected to supply from the Day Tank. I disconnected power to P1 and P2's outlet pressure was 4 PSI. With P1's power reconnected (Both pumps now running), P2's outlet pressure was 10 PSI.

All the Pumps have now been cleaned and reassembled. I will retest them today with a fuel supply connected directly to each pump to give a more accurate PSI comparison.

I will also confirm what the flow looks like.

 

[rickf]

Blow out that fuel line form the tank to pumps before hooking up to be sure there is nothing in there that will start the whole problem over again. And are you getting fuel out of the return line with the pumps running and everything hooked up? Will not be a lot but a small trickle back into the tank shows the return is not clogged and also shows that injection pump is getting enough fuel. You can disconnect that line from the tank and run it into a separate container to see if the fuel stops running out of it right before the unit shuts down. That would tell you there is a fuel problem.