[2023_ZL1-AUTO]

Quick questions, I think the answer is YES, but would appreciate confirmation! So, now that I have the drop in Katech Dual Fuel pump, I no longer need the JMS FuelMax installed, and I want to remove all of it. My question is: Can I simply remove all JMS stuff, but connect the RED wire and the WHITE wire from the JMS device together in the trunk (those go to the factory Red/Purple wire I spliced at the FPCM), and that will basically reconnect the factor Red/Purple where I made the splice? I will reconnect under the car at a later time, but I sprained my wrist, and can't really work up above the axle comfortably at the moment. I added a few photos for reference. Thanks in advance for your help!

[RobZL1]

That should work. I'd just leave the JMS in there, though. Maybe turn it down a smidge. Can't hurt to ensure the FPCM gets constant voltage. I plan to just leave mine in place with the DSX in-tank.

[2023_ZL1-AUTO]

Originally Posted by RobZL1

That should work. I'd just leave the JMS in there, though. Maybe turn it down a smidge. Can't hurt to ensure the FPCM gets constant voltage. I plan to just leave mine in place with the DSX in-tank.

Ok Thanks and probably the best idea, to just leave it!

Could the JMS drawing power 24/7 (green LED is always on), be a cause for draining my battery a bit over a few day period? I just replaced the original battery with a new AGM 800CCA (I should have went with Lithium). It seems like the battery gets drained a bit if I don't drive the car for a few days and I don't have my CTEK hooked up. Then I'll hook the CTEK up and it shows charging for several hours before reaching a full charge?

[KingLT1]

If the JMS will drain the battery if it's not on switched 12v.

[2023_ZL1-AUTO]

Originally Posted by KingLT1

If the JMS will drain the battery if it's not on switched 12v.

Thanks, I'll check that!

[RobZL1]

Originally Posted by KingLT1

If the JMS will drain the battery if it's not on switched 12v.

I thought the newer GM versions shut off after some period of time?

[2023_ZL1-AUTO]

Originally Posted by RobZL1

I thought the newer GM versions shut off after some period of time?

So, the night I completed my install, I didn't put things back in order until the next morning. The next morning I opened the trunk and I noticed the JMS had a green LED glowing. I emailed Ted Jannetty and asked if I might have not installed it incorrectly. He replied back" Fuel pump driver module is always on, green LED always on, you installed correctly" Mine never shuts off, I bought mine in late spring of 2023.

[RobZL1]

From the JMS instructions:

When to use a GM or Standard Voltage Output?
• If you have a GM that is 2010 or newer, you must use the GM specific unit.
• Starting in 2010 the fuel pump driver modules on GM vehicles are powered ON all of the time.
• JMS offers a special GM version of the FuelMAX for 2010+ GM vehicles.
• Use the Standard option ONLY if your vehicle utilizes “Key-ON +12v” to power the Fuel Pump or Pump Driver.

I had always assumed this to mean that it shut off internally after some time period. I've never had a battery drain issue on mine with it, even if it sat for almost two weeks. I don't have a battery tender on it.

[ZLRob]

NO, remove the FuelMax.. you do not want to be running it in conjunction with the dual fuel pump setup as the controller runs directly off the battery and not the FPDCM, so there will be a discrepancy in voltage and cause the secondary pump to have a different DC and ultimately fuel flow than the primary, and you don't want any of that drama.

To answer you original question, yes, reversing the wire at the connection point on the FPDCM will restore it back to factory. The exact colors you mentioned.

As for your Katech unit, is that thing brand new? Have you installed it yet, or what is going on with all that? It's important to you is why I am asking.

[2023_ZL1-AUTO]

Originally Posted by ZLRob

NO, remove the FuelMax.. you do not want to be running it in conjunction with the dual fuel pump setup as the controller runs directly off the battery and not the FPDCM, so there will be a discrepancy in voltage and cause the secondary pump to have a different DC and ultimately fuel flow than the primary, and you don't want any of that drama.

To answer you original question, yes, reversing the wire at the connection point on the FPDCM will restore it back to factory. The exact colors you mentioned.

As for your Katech unit, is that thing brand new? Have you installed it yet, or what is going on with all that? It's important to you is why I am asking.

OK Thanks. The Katech pump I have now is new and only a few months old, probably less that 500 miles of drive time.

[RobZL1]

But I mean, didn't Katech install the dual pump setup for you and leave the JMS intact? I see what you're getting at ZLRob, but I would think you'd still want to keep a constant voltage through the FPCM to the main pump. Just my opinion of course.

[2023_ZL1-AUTO]

Originally Posted by RobZL1

But I mean, didn't Katech install the dual pump setup for you and leave the JMS intact? I see what you're getting at ZLRob, but I would think you'd still want to keep a constant voltage through the FPCM to the main pump. Just my opinion of course.

Honestly, I'm not sure I told Katech the JMS was installed. It's totally covered and hidden way on the drive side of the trunk. So not near the batter etc. Unless they had to get to that connector, they would not have seen signs of the JMS the way I had it installed?

[ZLRob]

Originally Posted by RobZL1

But I mean, didn't Katech install the dual pump setup for you and leave the JMS intact? I see what you're getting at ZLRob, but I would think you'd still want to keep a constant voltage through the FPCM to the main pump. Just my opinion of course.

If you talk to Katech directly about the JMS they will tell you firsthand that their fuel pump setup has never been tested with the JMS and they don't recommend running it. Having personally tried it out that way prior to knowing that from Katech I saw how and why it would cause issues with the secondary.

Long story short, it's not worth it, and it's easier to fine tune the FPDCM from HPT if you are really looking for that much level of control out of the primary and by extension the secondary pump.

Katech has issues with their early dual fuel pump setups, that of which I own one and am currently having issues with myself. I love their products but the fact that it is so difficult to install and remove in and out of the tank A. and B. Traditionally requires tank removal to access the fuel pump (a non existent issue for me now), has me really irate about it all.

[KingLT1]

Originally Posted by RobZL1

I thought the newer GM versions shut off after some period of time?

Supposed too...green light on all the time is going to drain the battery over time.