LT1-LT4 Modifications 1993-97 Gen II Small Block V8

1993 LT1 Trans Am Fuel Pressure Regulator

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Old 08-14-2012, 01:38 PM
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Default 1993 LT1 Trans Am Fuel Pressure Regulator

So far I am just getting the car set up and going through everything as best I can to address issues and potential issues before I take the car out for a test run.

Here is where I am at with the car so far:

I have driven it exactly 2 miles since being given the car so I know nothing other then, "It ran fine when it was parked 2 years ago"!

I have fixed the initial miss which was a cracked porcelain on the #5 Spark Plug! The car runs much better but still pig rich and I am not truly sure how well the fuel pump and pressures are. I bought an Autometer 2179 Gauge but it came with no fittings so I am still waiting on that. I pulled off the vacuum line and there is for sure fuel getting past the diaphragm so I need to get a new Fuel Pressure Regulator and I think that will cure most of my remaining issues. I am posting these questions as "Most" threads are directly aimed at the 94-97 LT1's and I am not sure if they maintain the same parameters as a 93 model.

My main question(s) here are:

1) What are the fuel pressures I should see with a 1993 at:
A. Key On Engine Off?
B. Engine On Idle?
C. Engine On Full Throttle?
D. Engine On Vacuum Line Disconnected?

2) What brand of Fuel Pressure Regulator should I get? I am going to assume that AC Delco makes one but Oreilly's (closest shop) doesnt have one listed.

3) What are some other fuel related items that can cause the rich condition to occur with a 1993 model?

4) What are the actual differences between a 93 and 94-97 Cold Air Intake (CAI)?

Thanks,

Joe

Last edited by StraightTimeStirrups; 08-14-2012 at 01:43 PM.
Old 08-14-2012, 03:50 PM
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The only difference between '93 CAI and '94+ CAI is that the '94 has a shorter tube where the MAF sensor goes. And also 95+ LT1's have a little hose to vent the Opti I believe also that goes on the CAI.
Old 08-14-2012, 04:00 PM
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Also, the fuel pressure should be the same on all LT1s I believe. '93s have their own style fuel pressure regulator because of the '93 style Fuel rail. And also have 22LB injectors compared to 24LB on 94+ LT1s. '93s are Multiport F.I. while '94+ LT1s are Sequential Port F.I..

A few things that might normally cause a rich condition would be. Bad O2 sensors, exhaust leak (pre-O2 sensor), possibly the IAT sensor in the intake elbow is bad, or maybe leaky injectors.
Old 08-14-2012, 05:13 PM
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Turns out that someone put on an Aftermarket Adjustable Fuel Pressure Regulator on the car and it took me 3 hours to get the bugger out because there was NO ROOM to get to the Torx Screw! What a pain in the buuuuutt! I have no clue what brand it is as there is no markings on the AAFPR but I took it apart and the diaphragm was in two pieces so that is no doubt my source of running PIG RICH!

I am waiting to hear back from www.GMPARTSDIRECT.com so I can order a factory replacement AC Delco unit at $81.18.

Looking forward to having a properly running car to tryout!
Old 08-15-2012, 10:47 PM
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I bought a DEM FP10027 (Supposedly the OEM Part) Fuel Pressure Regulator from NAPA this morning and installed it. This car runs awesome now! I havent test driven it yet as I have a couple of water leaks in heater hoses I need to address but hopefully that will get down tomorrow morning.

It isnt easy fixing all of the prior owner induced issues, lol!

Joe



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