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Fuel Pressure

ctuinstra

ctuinstra

Goblin Guru
ctuinstra
I noticed that we are running 82lbs fuel pressure while at idle. Surely that has to be contributing to the excessive rich condition I have. I already have 60lbs injectors and with a high fuel pressure, it's probably off quite a bit. What is the factory pressure and why would it be so high?

This car uses the in-pump regulator with the return line at the fuel filter.
 
JSATX
The regulator is built into the pump, the filter does not regulate the pressure.

I was having this exact same issue and modified my system by removing the in pump regulator all together. I then installed a corvette fuel filter which does regulate the pressure. I’m much happier with this setup.
 
ctuinstra
JSATX said:
The regulator is built into the pump, the filter does not regulate the pressure.

I was having this exact same issue and modified my system by removing the in pump regulator all together. I then installed a corvette fuel filter which does regulate the pressure. I’m much happier with this setup.
Click to expand...

What about using something like this:

https://www.jegs.com/i/JEGS/555/159120/10002/-1

What pressure is the 'vette filter set to? Does it mount and connect much like the Cobalt?
 
Ross
The fuel rail had the same thread as my AC gauges, so I looped my red hose to plug the extra 2 ports, and put the yellow hose on the fuel rail.
19156


Here I did a 2nd gear WOT pull, and the fuel pressure went from 64PSI to 60PSI, with the stock LSJ fuel pump, stock 32lb/hr injectors.
19155
 
ctuinstra
Pretty neat idea there. I have a set of A/C gauges and never even thought of use them to check pressure. I should set them up just to check the inline gauge accuracy.

That drop I would think could be expected. I doubt that will cause much of an issue as the tuning can adjust for the small drop in fuel delivery.

64 PSI is a bit high for a 4 bar (58 PSI) system, but I doubt any donor car was spot on with just a spring and ball regulator.
 
Last edited:
M
Ross said:
The fuel rail had the same thread as my AC gauges, so I looped my red hose to plug the extra 2 ports, and put the yellow hose on the fuel rail.
View attachment 19156

Here I did a 2nd gear WOT pull, and the fuel pressure went from 64PSI to 60PSI, with the stock LSJ fuel pump, stock 32lb/hr injectors.
View attachment 19155
Click to expand...
This one looks like a electronic version which can be used up connect to the Ac pressure sensor. Little expensive and I wish the measurements range would be lower, but it's a start. https://www.hunterliberty.com/0-200-psi-transducer-with-05-45v-signal-schrader-valve-mount
 
M
Interesting, I think it would be easier to just cut the fuel line and put the sensor with a tee in the hose.

Easier in finding the right parts.

The right adapter is what currently scares me of doing the oil pressure Sensor too.
 
Ross
mike_sno said:
Interesting, I think it would be easier to just cut the fuel line and put the sensor with a tee in the hose.

Easier in finding the right parts.

The right adapter is what currently scares me of doing the oil pressure Sensor too.
Click to expand...
This post mentions the correct M12x1.75 threads for an oil pressure sensor.
This sensor fits in a pontiac G6 which is the LE9 Ecotec engine, probably fit in our engine without an adapter.
You could always take the plug out of your engine, and bring it to the auto parts store, just to make sure the threads are the same.
 
devianteng
I redid my fuel system this winter, and switched everything over -6AN fittings/lines. I added this sensor:

using this fitting:

I've not wired it up yet, but my plan is to wire it until the A/C Pressure sensor circuit, so I can log fuel pressure in HPT (running a boost reference setup, TurboSmart FPR6 regulator).

In theory, you should be able to run something like this with the factory setup (off the fuel filter), if you wanted to log fuel pressure:
www.ictbillet.com

LS 3/8 Fuel Line Quick Connector Adapter w/ 1/8" NPT Nitrous Port Gauge Source | AN811-02B - ICT Billet

This LS 3/8 Fuel Line Quick Connect Adapter Fitting has a 1/8" NPT Nitrous Fuel Port perfect for your LS swap. Parts made exclusively in the U.S. at ICT Billet.
www.ictbillet.com www.ictbillet.com


Regarding oil pressure sensor, SOME LSJs had the sensor on the block, while some had the sensor on the oil cooler itself. M12x1.75 should be the thread size/pitch for both locations, and IMO it'd be easiest to get an adapter to 1/8" npt so you can run standard/cheap pressure sensors.
www.racetronix.biz

Adapter, M12x1.75 Male » 1/8

Purchase Adapter, M12x1.75 Male » 1/8
www.racetronix.biz www.racetronix.biz
 
G
BOSCH SP0F000009

IncludesM10 x 1 to 1/8 in NPT Electrical & Mechanical Pressure and Boost Gauges; M12 x 1 to 1/8 in NPT Electrical & Mechanical Pressure and Boost Gauges; M12 x 1.75 to 1/8 in NPT Electrical & Mechanical Pressure and Boost Gauges; M14 x 1.5 to 1/8 in NPT Electrical Pressure and Temperature, Mechanical Pressure and Boost Gauges; M16 x 1.5 to 1/8 in NPT Electrical Pressure and Temperature, Mechanical Pressure and Boost Gauges
 
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