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Adjustable Fuel Pressure regulator questions

sideshowBob

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Joined
Nov 16, 2009
Messages
2,120
Location
North West Ontario
I have installed a TD adjustable fuel pressure regulator on my header tuned SW as I found it to be running a little high AFRs at wfo.
Questions:
-I set it up at 48psi initial key on not running...is this the correct way to do this?
-when running at idle the fuel pressure is @ 45psi...is this normal?
 

Are you still running the stock fuel pump?
I have run a snap on fuel pressure gauge off of my regulator to confirm gauge on regulator is accurate. Adjust fuel pressure until you get the afr you are looking for. Some have been as high as 52 psi key on engine off.
 
Yes Bob. 48/49 key on should be fine. You will see what closed loop is adding or subtracting from fuel delivery. 43 lbs is stock pressure. You'll know if she's running rich
 
If you are still running the stock pump just keep an eye on the 2 pin connector nearest to the pump. That's the one that gets hot.
 
Underhood heat can effect those gauges and it's another thing to keep in mind so don't be shocked if the pressure reads way low after there's some heat in the engine compartment.
 
Last edited:
Are you still running the stock fuel pump?
I have run a snap on fuel pressure gauge off of my regulator to confirm gauge on regulator is accurate. Adjust fuel pressure until you get the afr you are looking for. Some have been as high as 52 psi key on engine off.
I am running Hurricanes high out put fuel pump, return line over fuel pump basket, and direct power relay to fuel pump.
I have closed loop and I data log.
The data log indicated the closed loop was maxed out and AFRs were high 12s at WFO on the 300 tune so I installed the adjustable fuel pressure regulator to up the fuel pressure so the closed loop has more ability to maintain the tune AFR demands.
We don't have enough snow yet for me to do some full throttle data logs since I installed the adjustable fuel pressure regulator.
 
I am running Hurricanes high out put fuel pump, return line over fuel pump basket, and direct power relay to fuel pump.
I have closed loop and I data log.
The data log indicated the closed loop was maxed out and AFRs were high 12s at WFO on the 300 tune so I installed the adjustable fuel pressure regulator to up the fuel pressure so the closed loop has more ability to maintain the tune AFR demands.
We don't have enough snow yet for me to do some full throttle data logs since I installed the adjustable fuel pressure regulator.
I run mine at 47 PSI key on. CL pulls fuel most of the time even on my MS20 320HP header tune.
 
We now have enough snow and ice on our lakes for cooling and sliders.
I had my SW out yesterday for a lengthy ride and to test some of my off season changes and ensure there were no issues arising from the maintenance I completed.
Here's my initial observations.
-I had installed an adjustable fuel pressure regulator to try to lower AFRs from mid to high 12s to high 11s. I settled on 45psi key on and the resulting 300 flash WFO AFR is now 11.8 so perfect but the part throttle under 4800rpm AFR is now occasionally in the 10s but returns to a more normal AFR when cruising. I will have to do more data logging to get a better picture.
-The BOP rad kit seems to be working as advertised with temp at slow cruising speeds[riding with my wife] consistent at 170 - 174f but we were in good snow conditions so not really a test for effectiveness.
Great to get back out riding and so far so good:)
 
I believe Closed Loop only starts after 5000rpm and higher, which would explain the anomaly at 4800rpm.
 
It was giving even worse irregular AFRs when I had it running in the shop but before I rode it this year. I swapped the the 02 sensor with a new one and AFRs settled down but still rich off idle to under 5000 rpm....I don't run under 5000 rpm very often but I have the sled setup for trail riding with real low engagement RPM. Idle AFRs seem fine.
 
Are you still running a higher fuel pressure? If so, why no bring it down a little to see if that fixes your lower rpm rich condition and the cl should take care of the afr's above 5000 rpm.
 
That's a strange situation you're seeing there Bob. With that header tune you should be at 49lbs easily. I often see elevated AFR's while cruising as the closed loop is trying to conserve fuel with little demand for it. Key on pressure and a smooth idle is what i shoot for and be prepared to turn it up a bit on the colder days. Just curious what your boost looks like in the logs when you're seeing low AFR's
 
Are you still running a higher fuel pressure? If so, why no bring it down a little to see if that fixes your lower rpm rich condition and the cl should take care of the afr's above 5000 rpm.
I have the fuel pressure set at 45 key on using the gage that came on the regulator of course I have no idea what the original regulator would have read on the current gage so its apples and oranges. I was maxing out the Closed Loop before and still getting high AFRs.
I plan on doing more data logging and depending on closed loop percentage fuel and AFRs adjust the fuel pressure accordingly...maybe the low throttle AFR will improve then as well. I am beginning to think the previous fuel pressure regulator was under performing although the bonus of that was the sled was getting extremely good fuel economy before.
 
That's a strange situation you're seeing there Bob. With that header tune you should be at 49lbs easily. I often see elevated AFR's while cruising as the closed loop is trying to conserve fuel with little demand for it. Key on pressure and a smooth idle is what i shoot for and be prepared to turn it up a bit on the colder days. Just curious what your boost looks like in the logs when you're seeing low AFR's
Do you mean lean AFRs? If so I was seeing high 17s to 18 psi boost, AFRs @ 12.5, and fuel compensation around 124%.
Again I have to do more data logging with the current setup now to see where things are at.
 


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