Racetronix Pump Still Kicking My A@@!!

[tatasta]

Well, I took the car out again today to try and get my target AFR. I have 33# LS1 injectors which ran perfectly prior to installing a Racetronix pump. Naturally, before the new fuel pump, the fuel pressure was ~58#. After the install of the pump the car runs at 70-72#, which threw my AFR off by nearly a full number, I mean before I had 12.8:1 @ WOT and now it is ~11.9:1 @ WOT. I used the IFR spreadsheet and input the new values but still too rich.

I am to the point of asking for assistance because I am sure the remedy will cost some money so I would like to go the right way the first time.

My first choice is to install an external pressure regulator because I am sick of tweaking a tune that was great before the new fuel pump. Attached is a tune and log to look at but mostly I just need pointed in the right direction.

With this tune it was lean at idle to the point of nearly dying and at WOT the AFR was ok but it was missing/stuttering at high RPM. Never had this trouble before the high fuel pressure.

PLEASE HELP!!!!!

Thank you!!

[DrkPhx]

70-72 psi fuel pressure is too much for a LS1. Like you mentioned, you need to install a fuel pressure regulator to get it back in line to what is was before.

[joecar]

Post your spreadsheet.

[tatasta]

Joecar,

I haven't pestered you for a while.

This is the spreadsheet I used to calibrate the IFR for my injectors when I first installed them. It worked great until I put the Racetronix pump in.

Thanks

[mr.prick]

What's the part number on these injectors are they re-sized?

[tatasta]

What's the part number on these injectors are they re-sized?

Not sure of the part # at the moment. They are Bosch LS1 Design 3 flow tested at 33#. They came from FIC. As mentioned before, they were easy to tune for at 58psi with the stock pump and the car ran great. I was running at 95% + on duty cycle with the stock injectors is why I put the FIC injectors in.

Attached is a tune and log from the car before the fuel pump install. It was a bit rich but on N2O it was good.

I can get the part # in the morning.

Thank you

[joecar]

Joecar,

I haven't pestered you for a while.

This is the spreadsheet I used to calibrate the IFR for my injectors when I first installed them. It worked great until I put the Racetronix pump in.

ThanksNo worries... :)

When you measure rail pressure, is it constant 70-72 psi, does it deviate from that...? Is it 71±1 psi or better...? Is this what you used to recalculate the spreadsheet...?

[tatasta]

No worries... :)

When you measure rail pressure, is it constant 70-72 psi, does it deviate from that...? Is it 71±1 psi or better...? Is this what you used to recalculate the spreadsheet...?

It is a pretty steady 71#. I used 70 or 70.5 in that spreadsheet to calc the new IFR. So, yes this all I used to come up with the values.
Did I miss something?

[tatasta]

joecar,

Also, they are 33# injectors.

[ND2RACE]

If all you did was install a pump and the fuel pressure went up why would you tune around that? Am I missing something?

Sounds like you knocked the fuel pressure regulator loose in the tank.

[tatasta]

If all you did was install a pump and the fuel pressure went up why would you tune around that? Am I missing something?

Sounds like you knocked the fuel pressure regulator loose in the tank.

I guess I could have. Never thought of that happening. I'm pretty sure that it was assembled right. Luckily, I cut an access door. I think I willl take it out and check it over. Fuel pressure was 58 with one pump then 71 with the other.

Thanks

[tatasta]

ttt...

I guess the question then is: Can the added output of the new pump affect the operation of the stock regulator? I see that you can buy a replacement regulator. Should that be the next step?

I guess one of the intents of this thread was to get info on how to add an external regulator to my system. The addition of a regulator is the obvious choice. It would fix my problem but I am sure it's not that simple. I have searched for the best way to install an external regulator but have, as usual, there are arguments everywhere.

So, yes. In my opinion, fuel pressure should be right before it gets to be a tuning issue.

What should I do?

Thank you!!

[DrkPhx]

Do a search on ls1tech.com in the Fuel section. The more common and accepted method is to install a adjustable fuel pressure regulator on the passenger side after the fuel rail.

[joecar]

...
Sounds like you knocked the fuel pressure regulator loose in the tank.

I guess I could have. Never thought of that happening. I'm pretty sure that it was assembled right. Luckily, I cut an access door. I think I willl take it out and check it over.
...sDid you get a chance to check that the regulator is connected properly and that nothing is restricting the short return plumbing...?

[DrkPhx]

My guess is it's installed correctly. The Racetronix pump is a modified Walbro for increased flow, that along with the voltage booster almost always increases fuel pressure over stock.

[tatasta]

No, I wont get to removing the pump until next weekend. I feel pretty confident on the accuracy of the install but, if I did screw up something with the regulator, what did I likely do? I never had to take the reg. out so I'm not sure what the deal is.

Also, I never did put the new voltage boosting harness in it. Once I fired it up with just the pump, the last thing I wanted was more fuel pressure.

If I was to put a regulator on after the passenger side rail, would I need to plumb a return line in too?

I'll check out LS1Tech for some ideas.

Thanks!

[DrkPhx]

No, I wont get to removing the pump until next weekend. I feel pretty confident on the accuracy of the install but, if I did screw up something with the regulator, what did I likely do? I never had to take the reg. out so I'm not sure what the deal is.

Also, I never did put the new voltage boosting harness in it. Once I fired it up with just the pump, the last thing I wanted was more fuel pressure.

If I was to put a regulator on after the passenger side rail, would I need to plumb a return line in too?

I'll check out LS1Tech for some ideas.

Thanks!

Search for my friend's posts (Waterbug1999) He installed an adjustable FPR off the passenger fuel rail and did a nice, clean install.

[joecar]

Let us know what you find and how you get it resolved.

[acomp917]

I don't know if this is a help or not. If you look at my avatar, you will see 2 255lph pumps in parallel. I had this hooked to a stock LT1 reg(modified mounting, select "personal junk" in signature, go to V8-S10 pics). With both pumps running under low fuel consumption, I COULD NOT regulate pressure to 3bar. The stock return port(pintle) is ~.125" dia, most aftermarkets are only slightly larger.

I found it is much better to stage pumps based on required fuel, and then only to have pumps of required size. Using battery current to move excess fuel just raises the temp and lowers the density. I have noticed slight changes in AFR(overall) on OL systems that I drove many miles.

S

[ND2RACE]

Did you get a chance to check that the regulator is connected properly and that nothing is restricting the short return plumbing...?

This is what i mean, I have been running a Racetronix system for two years now with no variation from the stock 58psi. I would just be concerned that the mechanical part is working properly, hope you can figure it out.

[tatasta]

Did you get a chance to check that the regulator is connected properly and that nothing is restricting the short return plumbing...?


This is what i mean, I have been running a Racetronix system for two years now with no variation from the stock 58psi. I would just be concerned that the mechanical part is working properly, hope you can figure it out.

The regulator is connected correctly. I need to spend more time on it to see if something is plugged. I bought a complete used stock pump/bucket to put in and see what happens. If it works, I'll change out the reg. If it doesn't, then I'll start on looking for line problems.

Thanks to everyone for all the help