Troubleshooting Rubicon locker pump air leak

Viking Jeeper

Viking Jeeper

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Several months ago I moved my factory Rubicon locker pumps under the hood. After the install pumps worked as intended by running a few seconds until enough pressure had been built up then shut off. Recently I noticed that both pumps will run for a few seconds then shut off as normal but will run again about every 5-10 seconds for a very short period of time. In troubleshooting I removed the outlet hose from the pump and stopped it with my finger. The pumps rapidly start/stop now every second or two. I thought I should be able to make a good enough seal to stop the pump with my finger. Both pumps are doing the same thing. Bottom line is I am trying to find an air leak and cant get through what I would think is the first step, plug the air outlet with a finger and ensure the pump shuts off as it should.
 
The finger should be enough to stop them, so it seems odd they both don't cycle properly. Are the vents tied together or separated?
 
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Irun said:
The finger should be enough to stop them, so it seems odd they both don't cycle properly. Are the vents tied together or separated?
Click to expand...
Exactly, and it's odd that they're both doing the same thing. If both cycle on-off-on with your finger firmly and completely blocking the output port my only guess is they both eventually developed problems. I've had one pump go bad and do the same thing but so far, just that one.
 
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This video shows the pump with the air line hooked up. Video is really just for audio.


Listen to what happens when I try to plug with my finger

Both pumps are doing the same thing.
 
Viking Jeeper said:
By vent lines I have to assume you mean output. I have done that, shown in my second video above. Pump cycles rapidly on/off when I plug the output with my finger.
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Did you unplug both lines from both pumps? The shared vent lines, what allows the pressure to bleed off immediately ofter the pumps are turned off, is the only thing they have in common. Just trying to eliminate any trouble shooting variables!
 
Irun said:
Did you unplug both lines from both pumps? The shared vent lines, what allows the pressure to bleed off immediately ofter the pumps are turned off, is the only thing they have in common. Just trying to eliminate any trouble shooting variables!
Click to expand...
Still unsure of what you mean by vent lines. Each pump has a small and a large air line attachment points. I view the larger rubber line to be an input and I dont see how that can have anything to do with the issues I'm seeing. The larger lines are connected with a T and it terminates high on the firewall. I'll unplug that tomorrow and check.
 
The two ports on each pump are

1. a 5 psi output that goes to the locker
2. a vent that allows the pressure to quickly bleed off, when the pumps are turned off

If the pump didn't have this #2 "vent", the system would hold air, keeping the locker engaged. FWIW, I've tested this and seen that the lockers can stay engaged for 30 to 60 seconds, possibly longer, after shutting off the pumps. Since these vents don't have to operate independently, the two pump bleed off vents are tied together by the factory.

Like I said previously, since #2 is the only thing the two pumps share, besides 12v power, I was simply suggesting to eliminate every variable possible when testing. Although unlikely, with a shared vent, there is always the possibility that pressure from one pump is bleeding over to the other. Without that shared connection, that possibility is eliminated.

If you remove both hoses from both pumps, testing each separately, and they still cycle quickly, the problem is the pumps themselves. It is odd that they both went at the same time though.
 
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