[KingLT1]

Originally Posted by TJay74

i would use the table from a SS 1LE car for that table.

Also you wont see the voltage increase in HPT, only at the actual wires at the rear. This is because the JMS catches the signal and increase it and then pushes the increase to the pump. The change never makes it thru the module is my understanding from talking with Ted.

The JMS directly increases the output voltage to the pump.

Agree...which makes me wonder why you wouldn't hook the JMS directly to the wire coming out of the FSCM to the fuel pump so it bypasses the FSCM. It reads like rob has it the JMS boosting the control module, then the module still regulates voltage to the pump. Or did I read his diagram wrong?

[steelheadrob]

Originally Posted by KingLT1

Agree...which makes me wonder why you wouldn't hook the JMS directly to the wire coming out of the FSCM to the fuel pump so it bypasses the FSCM. It reads like rob has it the JMS boosting the control module, then the module still regulates voltage to the pump. Or did I read his diagram wrong?

Yeah that what seems like is happening.

I have debated connecting it up directly by tapping into the grey wire that runs to the fuel pump. To see what happens and if I can isolate where my problem is at. But the voltage on this wire varies so it would not be supplying a consistent 12.xx volts to the jms no sure what this would impact.

At this point I think I am going to start from ground zero, pull it back out, run the red wire directly from the battery and recrimp the white wire to the red wire with the purple tracer connection and use a different body ground to see if I see any improvement. If that does not work then I am going to connect directly to the fuel pump with the car off and run fuel into a bucket to measure the volume coming from the fuel pump to see if there is a problem with the in tank pump.

[Nmolina9239]

Rob, how did you make out on this one?

[JANNETTYRACING]

Originally Posted by steelheadrob

Yeah that what seems like is happening.

I have debated connecting it up directly by tapping into the grey wire that runs to the fuel pump. To see what happens and if I can isolate where my problem is at. But the voltage on this wire varies so it would not be supplying a consistent 12.xx volts to the jms no sure what this would impact.

At this point I think I am going to start from ground zero, pull it back out, run the red wire directly from the battery and recrimp the white wire to the red wire with the purple tracer connection and use a different body ground to see if I see any improvement. If that does not work then I am going to connect directly to the fuel pump with the car off and run fuel into a bucket to measure the volume coming from the fuel pump to see if there is a problem with the in tank pump.

Your problem is not in the JMS or the way you installed it.

It is in your tune.

Ted.

[JANNETTYRACING]

Originally Posted by KingLT1

Agree...which makes me wonder why you wouldn't hook the JMS directly to the wire coming out of the FSCM to the fuel pump so it bypasses the FSCM. It reads like rob has it the JMS boosting the control module, then the module still regulates voltage to the pump. Or did I read his diagram wrong?

Because your fuel pump is not a standard voltage pump, it is a pulse width modulated pump.

The FPCM takes system voltage and converts it to a PWM signal to control pump speed.

If you connect 12 volts to the pump it will try and run full bore making max pressure blowing open the bypass and burning out the pump.

Ted.

[steelheadrob]

Originally Posted by JANNETTYRACING

Your problem is not in the JMS or the way you installed it.

It is in your tune.

Ted.

Ted, just sent you an email.

[KingLT1]

Originally Posted by JANNETTYRACING

Because your fuel pump is not a standard voltage pump, it is a pulse width modulated pump.

The FPCM takes system voltage and converts it to a PWM signal to control pump speed.

If you connect 12 volts to the pump it will try and run full bore making max pressure blowing open the bypass and burning out the pump.

Ted.

Makes sense...Thx

[steelheadrob]

Ted was right. It was a problem in the tune. He pointed me to the FCSM tables which I had not access to previously, after downloading the beta version of HP Tuners I was able to access them. The Max Desired Pressure table in the FCSM still had the stock values, I updated them to match my ECM Max Desired Pressure table. I also changed the Regulation pressure table from 450 to 500kpa. Now my lowside is consistently holding above 72psi. I have only tested it with pump gas so far will mix up higher E content fuel this weekend and test it some more. I am suprised it requires both Max Desired Pressure tables to be updated, since guys have been running the BAP pumps before there was access to the FSCM tables. Also my data logs showed I as commanding 72 psi with only the one table updated.

I logged max volts at the grey wire that goes to the fuel pump, previously it was reading 12.xx volts, now it is reading 13.3 volts. Eventhough I am pushing 17.4 volts at it the computer appears to be limiting to only what I need to achieve the commanded 72psi. So it looks like I have quite a bit of headroom to add higher E content.

[KingLT1]

That's good news. For some reason I assumed you had all that tuned already.

[Joshinator99]

Originally Posted by KingLT1

That's good news. For some reason I assumed you had all that tuned already.

I was thinking the exact same thing... sorry we missed that Rob!

[G2K]

Can wait for your video Rob, I'm going around and around to install the BAP on mine.

[steelheadrob]

Originally Posted by KingLT1

That's good news. For some reason I assumed you had all that tuned already.

Originally Posted by Joshinator99

I was thinking the exact same thing... sorry we missed that Rob!

For some reason the FSCM tables were left stock when I got my lt4 tune done last fall. It all makes sense now. I ran some E55 last weekend, lowside held in the 70s. I am going to bump of the e content and do some more testing this coming weekend.

[steelheadrob]

Originally Posted by G2K

Can wait for your video Rob, I'm going around and around to install the BAP on mine.

I am going to load up my install video tomorrow night. Hopefully it helps you get yours straighten out.

[G2K]

Got mine installed last night... thanks to your video Rob, also thanks to previous old posts from TMS and Tjay74... all very informative... got my JMS working correctly on my first try and now my low side is constantly over 70psi.. what a thing of beauty... I even saw 80psi at one point.

this is only a 3rd gear pull... I'll run a 1-4 gear later this afternoon if the rain goes away.... Pretty glad I went with the JMS, I thought my pump was failing.

Now @ 5998rpm
AFR 12.1-12.3
low side 76psi
rail 2900psi
inj 5.4 ms

E64 fuel stock LT4 fuel system @ 7.8PSI... It's looking like I can actually pulley down to 10psi... but im already at 619rw... dont know if i should push it more car is running so good.

So for future people reading this post... the JMS is definitely worth it.