how to install a fuel pressure gauge in a crossfire engine
12-19-2015, 01:27 AM
#1
Safety Car
Thread Starter
how to install a fuel pressure gauge in a crossfire engine
i know some braze a valve and the defunct DSC used to sell and inline one
simply, any one can give me a step by step or give me a link for this
i installed a 85-87 tpi pump in my 82 and I now would like to know what is up
and the c3 guys are mostly carbs as you all know
simply, any one can give me a step by step or give me a link for this
i installed a 85-87 tpi pump in my 82 and I now would like to know what is up
and the c3 guys are mostly carbs as you all know
12-19-2015, 08:02 AM
#2
Burning Brakes
mine look like this https://www.corvetteforum.com/g/picture/1347319 but it is easyer to just weld in a valve on the tube 
12-19-2015, 08:29 AM
#3
If its just a temporary test you could check it at the fuel filer area, the 82-84 vettes use fuel filters with slide on/clamped hoses. Just get a universal pressure test kit, they usually have a tee in them. You might have to use a longer hose section & make a loop to avoid kinking it.
Last edited by ex-x-fire; 12-19-2015 at 08:32 AM.
12-19-2015, 09:29 AM
#4
I believe that "ex-x-fire" has a quick/short term solution for you. If you wanted something more permanent I'd think a silver brazed Schrader port in a factory fuel line might be the better idea. I don't believe a fixed gauge is required and if you use the generally suggested installs you've now got multiple failure points.
There is NiCopp or Cunifer tubing available with likely correct fuel nuts so you hand form the tubing and silver braze a tee so that the Schrader can be a serviceable part.
I believe to modify a factory fuel line you need to start with the correct '82 fuel line.
There is NiCopp or Cunifer tubing available with likely correct fuel nuts so you hand form the tubing and silver braze a tee so that the Schrader can be a serviceable part.
I believe to modify a factory fuel line you need to start with the correct '82 fuel line.
12-19-2015, 09:58 AM
#5
Safety Car
Thread Starter
If its just a temporary test you could check it at the fuel filer area, the 82-84 vettes use fuel filters with slide on/clamped hoses. Just get a universal pressure test kit, they usually have a tee in them. You might have to use a longer hose section & make a loop to avoid kinking it.
but is this an unregulated pressure?
i need to see regulated and adjust if needed
otherwise, it could be a nice idea
i saw that in the "famous" how to tune cfi article and simply forgot
the car makes me dumb
Last edited by slickfx3; 12-19-2015 at 10:00 AM.
12-21-2015, 04:22 PM
#7
Racer
Pump pressure runs to the passenger side (forward) injector tower, where the regulator is located. The fuel filter is an easy line-in to catch a failing pump, but to read regulated pressure (best tested at WOT), you need to tap between the TBs as in the photo above. Check @ both locations before buying anything--your wallet and watch will thank you when you don't have to replace working parts.
If modding is your goal, keep in mind that without provisions for improved airflow and a tunable computer, increasing regulated fuel pressure much beyond the recommended 9-13 psi will likely result in power loss and a poor (rich) running engine. Once in closed loop, the ECU will see the extra fuel when the upstream O2 indicates a rich mixture, and it will attempt to rectify the situation by reducing injector pulse widths. However, due to limitations of the era, the computer's pre-programmed window for adjustment is relatively narrow, and it will be unable to produce optimum power and efficiency through the full gamut of running conditions.
By its very nature, the Crossfire design also contributes complications. The injectors are stagger-sized for series plumbing, so changes to fuel pressure will not affect both banks of cylinders symmetrically. In addition, only bank 1 is equipped with an O2 sensor. The ECU has no indication of bank 2's A/F mixture, and thus was not granted the ability to correct a cross-bank imbalance by modifying the pulse width of an individual injector.
Ultimately, you'll find that modifying fuel pressure alone will throw both the banks and the general A/F mixture out of balance, which will make your car very, very grumpy. You can try to make up the difference with throttle linkage adjustments, but on a stock engine and ECU, best practice is generally FIWITIW: feed it what it thinks it wants.
Last edited by 84Z51J; 12-21-2015 at 04:57 PM.
12-21-2015, 05:56 PM
#8
Safety Car
Thread Starter
Pump pressure runs to the passenger side (forward) injector tower, where the regulator is located. The fuel filter is an easy line-in to catch a failing pump, but to read regulated pressure (best tested at WOT), you need to tap between the TBs as in the photo above. Check @ both locations before buying anything--your wallet and watch will thank you when you don't have to replace working parts.
If modding is your goal, keep in mind that without provisions for improved airflow and a tunable computer, increasing regulated fuel pressure much beyond the recommended 9-13 psi will likely result in power loss and a poor (rich) running engine. Once in closed loop, the ECU will see the extra fuel when the upstream O2 indicates a rich mixture, and it will attempt to rectify the situation by reducing injector pulse widths. However, due to limitations of the era, the computer's pre-programmed window for adjustment is relatively narrow, and it will be unable to produce optimum power and efficiency through the full gamut of running conditions.
By its very nature, the Crossfire design also contributes complications. The injectors are stagger-sized for series plumbing, so changes to fuel pressure will not affect both banks of cylinders symmetrically. In addition, only bank 1 is equipped with an O2 sensor. The ECU has no indication of bank 2's A/F mixture, and thus was not granted the ability to correct a cross-bank imbalance by modifying the pulse width of an individual injector.
Ultimately, you'll find that modifying fuel pressure alone will throw both the banks and the general A/F mixture out of balance, which will make your car very, very grumpy. You can try to make up the difference with throttle linkage adjustments, but on a stock engine and ECU, best practice is generally FIWITIW: feed it what it thinks it wants.
12-21-2015, 11:46 PM
#9
Race Director
12-22-2015, 04:29 AM
#10
This is '84 metering. "84Z51J" mentions a few irrelevant things.
OP - you need to remember yours is an '82. Similarities yes but .......
For an '82 this is likely a good read and there's also the C3 section.
http://forums.superchevy.com/super-c...tion-problems/
OP - you need to remember yours is an '82. Similarities yes but .......
For an '82 this is likely a good read and there's also the C3 section.
http://forums.superchevy.com/super-c...tion-problems/
Last edited by WVZR-1; 12-22-2015 at 05:20 AM.
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slickfx3 (12-22-2015)
12-22-2015, 08:28 PM
#11
Safety Car
Thread Starter
This is '84 metering. "84Z51J" mentions a few irrelevant things.
OP - you need to remember yours is an '82. Similarities yes but .......
Attachment 47940517
For an '82 this is likely a good read and there's also the C3 section.
http://forums.superchevy.com/super-c...tion-problems/
OP - you need to remember yours is an '82. Similarities yes but .......
Attachment 47940517
For an '82 this is likely a good read and there's also the C3 section.
http://forums.superchevy.com/super-c...tion-problems/
started the car, no leaks so far and drive it.
i saw some hoses near the mechanical pump blockoff plate is where i can temporarily install is test gauge.
so i am closer to knowing what my 87 tpi pump is doing and adjusted at....
Last edited by slickfx3; 12-22-2015 at 08:34 PM.
12-22-2015, 08:32 PM
#12
Safety Car
Thread Starter
the return line is off the rear tb the afpr slows the pressure upstream creating a bottleneck, all the gas behind it is in a traffic jam
12-22-2015, 08:37 PM
#13
Safety Car
Thread Starter
Pump pressure runs to the passenger side (forward) injector tower, where the regulator is located. The fuel filter is an easy line-in to catch a failing pump, but to read regulated pressure (best tested at WOT), you need to tap between the TBs as in the photo above. Check @ both locations before buying anything--your wallet and watch will thank you when you don't have to replace working parts.
If modding is your goal, keep in mind that without provisions for improved airflow and a tunable computer, increasing regulated fuel pressure much beyond the recommended 9-13 psi will likely result in power loss and a poor (rich) running engine. Once in closed loop, the ECU will see the extra fuel when the upstream O2 indicates a rich mixture, and it will attempt to rectify the situation by reducing injector pulse widths. However, due to limitations of the era, the computer's pre-programmed window for adjustment is relatively narrow, and it will be unable to produce optimum power and efficiency through the full gamut of running conditions.
By its very nature, the Crossfire design also contributes complications. The injectors are stagger-sized for series plumbing, so changes to fuel pressure will not affect both banks of cylinders symmetrically. In addition, only bank 1 is equipped with an O2 sensor. The ECU has no indication of bank 2's A/F mixture, and thus was not granted the ability to correct a cross-bank imbalance by modifying the pulse width of an individual injector.
Ultimately, you'll find that modifying fuel pressure alone will throw both the banks and the general A/F mixture out of balance, which will make your car very, very grumpy. You can try to make up the difference with throttle linkage adjustments, but on a stock engine and ECU, best practice is generally FIWITIW: feed it what it thinks it wants.
12-23-2015, 02:52 PM
#15
Racer
My bad on the location of the regulator! I don't think I was terribly off base with the rest--bumping up fuel pressure in search of more power, without any supporting mods, is generally a bad idea. While I wasn't sure whether that was the OP's goal (it appears it was not), I figured there was a chance I could save him some frustration by including an explanation specific to the Crossfire injection system. Overkill perhaps
That could certainly be the case; factory specs are not the Rosetta Stone of performance by any means, and you're right to investigate! I would suggest doing some datalogging to confirm though--see what your car does at WOT.
Last edited by 84Z51J; 12-23-2015 at 03:00 PM.