Fuel pressure gauge...

bobtodd · 08-03-2002, 08:43 PM

Will a fuel pressure gauge let me know if I'm running lean? What should the FP be at when at WOT? I've got a gauge under the hood but am looking to get one for the dash so I can see what FP is at under load.

jason 95gts · 08-03-2002, 09:12 PM

A fuel pressure gauge won't tell you if you are lean. You need to get a EGT (exhaust gas temperature) gauge if you wan't to know if you are rich or lean . On a naturally aspirated car it should be around 1400 to 1500 degrees at wide open throttle.

95mustanggt · 08-03-2002, 10:37 PM

A fuel pressure gauge will give you an idea if you are running lean. If you're pressure drops off you know your lean. Flow and pressure are related. But jason 95gts is right the only true way to tell if you are lean is to measure the exhaust gases.

ultraflo · 08-03-2002, 10:45 PM

Fuel pressure should be 40psi @ WOT... that's a good, safe place to start anyhow.

As for EGT's... depending on how close the temp. probe is to the exhaust port (mine is 2" from the cyl. head), you should be in the range as mentioned... though it is my opinion that 1500 is a bit on the lean side. I'd shoot for 1350-1450... anything in the 1300 range is safe. I'm pleased w/ my Computech unit which has a recall for high and low. Digital/real-time EGT gauges are much better than the rich/lean gauges that go off the O2 sensor.

As for which cylinder to mount the probe... check you plugs to see which cyl. runs the leanest and monitor that one. The front two cylinders or #2 or #7 is a good place to start...

bobtodd · 08-04-2002, 12:10 AM

Can you explain a little more about an EGT gauge? What does that stand for..exhaust gas temp? Where do you mount it and does it just take the temp of the exhaust? Thanks for the info!!

ultraflo · 08-04-2002, 12:35 AM

...you got it!

Exhaust Gas Temperature

With the Computech units, you can either get the clamp-on version or the weld-in bung version... the weld-in bung version allows you to move the temp sensor from cylinder to cylinder (if you weld a bung in every header tube)

You have to drill a hole in the header tube of your choice, insert the temp probe, run the wire through the firewall, and insert it into the handheld unit which displays real-time temp (for example, when you get it hooked up for the first time and turn it on it reads close to room temp if the motor hasn't been run).

It really is a nice tool to have and you can watch your EGT's while you're driving around to see how the motor acts... the hand held unit also has a high and low memory that recalls the highest/lowest temp reached, which comes in handy at the dragstrip after making a pass for example, much better than a rich/lean gauge IMHO.

I use the clamp-in version at the moment, but would like to upgrade to the screw-in version and weld bungs into every header tube... the big dogs have one in every tube that runs to the data logger which they read after making a pass.

If I missed anything let me know as I'm gonna stop rambling now

edited to add ballpark figures at top...

bobtodd · 08-04-2002, 10:18 AM

Gothca!!...thanks for the info. I appreciate it. I also found a site that sells them and it kind of explained how they work. Thanks again!

08-03-2002, 08:43 PM	#1
bobtodd Registered Member Join Date: Dec 1998 Location: WI, U.S Posts: 255	Fuel pressure gauge... Will a fuel pressure gauge let me know if I'm running lean? What should the FP be at when at WOT? I've got a gauge under the hood but am looking to get one for the dash so I can see what FP is at under load. __________________ 91 LX - 10.5:1 pistons, ported 289 heads, Ultradyne 588 cam, Cobra upper/lower, MSD, JBA long tube headers, Flowmaster, Richmond 4:10, roll cage, monster tach...FUN!! 95 SHO - K&N filter

08-03-2002, 10:37 PM	#3
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	A fuel pressure gauge will give you an idea if you are running lean. If you're pressure drops off you know your lean. Flow and pressure are related. But jason 95gts is right the only true way to tell if you are lean is to measure the exhaust gases. __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

08-03-2002, 10:45 PM	#4
ultraflo NX dealer-man Join Date: Sep 1998 Location: Peoria, Illinois Posts: 977	Fuel pressure should be 40psi @ WOT... that's a good, safe place to start anyhow. As for EGT's... depending on how close the temp. probe is to the exhaust port (mine is 2" from the cyl. head), you should be in the range as mentioned... though it is my opinion that 1500 is a bit on the lean side. I'd shoot for 1350-1450... anything in the 1300 range is safe. I'm pleased w/ my Computech unit which has a recall for high and low. Digital/real-time EGT gauges are much better than the rich/lean gauges that go off the O2 sensor. As for which cylinder to mount the probe... check you plugs to see which cyl. runs the leanest and monitor that one. The front two cylinders or #2 or #7 is a good place to start... __________________ RLS Racing! 93 LX 9.20 @ 147mph 03 Mach 1 12.39 @ 116mph

08-04-2002, 12:10 AM	#5
bobtodd Registered Member Join Date: Dec 1998 Location: WI, U.S Posts: 255	Can you explain a little more about an EGT gauge? What does that stand for..exhaust gas temp? Where do you mount it and does it just take the temp of the exhaust? Thanks for the info!! __________________ 91 LX - 10.5:1 pistons, ported 289 heads, Ultradyne 588 cam, Cobra upper/lower, MSD, JBA long tube headers, Flowmaster, Richmond 4:10, roll cage, monster tach...FUN!! 95 SHO - K&N filter

08-04-2002, 12:35 AM	#6
ultraflo NX dealer-man Join Date: Sep 1998 Location: Peoria, Illinois Posts: 977	>1300=rich, <1450=lean (ballpark) ...you got it! Exhaust Gas Temperature With the Computech units, you can either get the clamp-on version or the weld-in bung version... the weld-in bung version allows you to move the temp sensor from cylinder to cylinder (if you weld a bung in every header tube) You have to drill a hole in the header tube of your choice, insert the temp probe, run the wire through the firewall, and insert it into the handheld unit which displays real-time temp (for example, when you get it hooked up for the first time and turn it on it reads close to room temp if the motor hasn't been run). It really is a nice tool to have and you can watch your EGT's while you're driving around to see how the motor acts... the hand held unit also has a high and low memory that recalls the highest/lowest temp reached, which comes in handy at the dragstrip after making a pass for example, much better than a rich/lean gauge IMHO. I use the clamp-in version at the moment, but would like to upgrade to the screw-in version and weld bungs into every header tube... the big dogs have one in every tube that runs to the data logger which they read after making a pass. If I missed anything let me know as I'm gonna stop rambling now edited to add ballpark figures at top... __________________ RLS Racing! 93 LX 9.20 @ 147mph 03 Mach 1 12.39 @ 116mph

08-03-2002, 09:12 PM	#2
jason 95gts Registered Member Join Date: Jul 2002 Location: belle chasse La. Posts: 47	A fuel pressure gauge won't tell you if you are lean. You need to get a EGT (exhaust gas temperature) gauge if you wan't to know if you are rich or lean . On a naturally aspirated car it should be around 1400 to 1500 degrees at wide open throttle. __________________ DSS306 SHORTBLOCK,STAGE2 VICTOR JR. HEADS,AEROMOTIVE FUEL SYSTEM,TFS INTAKE,50# INJECTORS,MSD6AL,D-1 PROCHARGER,TKO TRANS.,CENTERFORCE CLUTCH,MAC LONGTUBE HEADERS,FLOWMASTERS,OFF-ROAD H-PIPE,3.73 GEARS, 6 POINT ROLL CAGE, ALL IN A 1995 GTS

08-04-2002, 10:18 AM	#7
bobtodd Registered Member Join Date: Dec 1998 Location: WI, U.S Posts: 255	Gothca!!...thanks for the info. I appreciate it. I also found a site that sells them and it kind of explained how they work. Thanks again! __________________ 91 LX - 10.5:1 pistons, ported 289 heads, Ultradyne 588 cam, Cobra upper/lower, MSD, JBA long tube headers, Flowmaster, Richmond 4:10, roll cage, monster tach...FUN!! 95 SHO - K&N filter

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