**Disclaimer - This is a simple mod, but I will explain everything as best I can. If you screw something up though - its not my fault! Read the instructions on ALL parts before even taking them out of their boxes!**

After purchasing an Aeromotive Adjustable Fuel Pressure Regulator I needed a way to monitor my fuel pressure at WOT with a bit more finesse then an autoparts store mechanical gauge taped to my windshield . Also, since my oil pressure sending unit was broken quite some time ago I decided to just go for two aftermarket gauges, and ventured out blindly to find some info. After a lot of snooping around in my engine bay for space and browsing through summit, I got a parts list that I hoped would work. It did . It ended up being cheaper then I had thought to boot! A little over 200 bucks for everything. The layout of some things may be different on your car since my LT1 is a 93. Because of this I will not bother to tell exact lengths for wiring and such, so measure it out for your own individual application!

Here is my parts list. I suggest digital instead of mechanical gauges for safety reasons, since they will be ran inside the car. I got the plane jane Summit brand oil pressure sensor because the matching series of the fuel gauge was out of stock and on backorder for a month! I just scrolled through their gauges until I found one that looks similar enough. More pictures will be added eventually. Here is my exact parts list from summit. If you change the gauges, be sure to get the recommended sending unit from the gauges "suggested parts" page!!! Some brands may use different ohm ranges for the gauges, making them inaccurate or non functional with other sending units!

Here are the links to each products page:
Dual gauge Pillar Pod. Could not find the full a-pillar replacement with pod, so I got this "clip on" one. It is very inexpensive, and was cake to install. Just mock up where you want it, mark and drill the holes on each corner into the factory a-pillar(remove it first, there are a couple wires under it. It just clicks out easily), and use the included push tabs to hold it in place. Was a very close color and texture match to my stock black a-pillar, and ended up looking better then I thought it would.

1/4 NPT Male x 1/8 NPT Female Bushing. This is to put the oil pressure sending unit threads (male 1/8 NPT) in the stock block holes(1/4NPT). I put mine in the factory location for 93's - right above the oil filter. Other years used a top mount behind the intake. That top one can be totally ignored and the bottom used without harm - other years just had a 1/4NPT plug over the mounting location above the oil filter. Depends on how much clearance you have at each location - you can use whichever you want and plug the other one, or leave the factory one in tact. Now, the problem with this bushing is that pretty blue anodized surface. Single terminal gauges, like oil pressure sensors, must be grounded to the block. See where I am going? The anodized coating prevents it from grounding, and will keep the gauge from working. I could not find the proper size bushing in a conductive steel, brass or aluminum(must be 1/4NPT male threads!) on Summit, so got this one hoping it either would still ground, or at least be easy to remove the coating. I tested it for continuity with a digital multimeter when I got it(one probe in the inner 1/8 npt threads, other on top the face) and showed NO conductance. Drats. It was no match for my Dremel and wire brush attachment though . I easily removed the blue coating on the outer threads and face, and some of the inner threads with the wire brush attachment. For the rest of the inner threads, I used a bit of light sandpaper twisted into a tube. Just get the blue off, do not ruin the threads. One you think it is good enough, screw it onto the oil sending unit and test for continuity with one probe on the outside of the bushings 1/4 NPT male threads(where it will contact the block), and the other prober on the threads of the 1/8NPT male portion of the sending unit. If they show "0", or full short through the bushing, you are good to go now . If you get a conductive brass, steel, or aluminum bushing with no coating you will not need to do any of that. It only took me around 5 minutes to correct though. The fuel pressure sending unit is a double terminal guage which is grounded externally, so the connector used does not matter.

Digital Fuel Pressure Gauge. Simple and clean, just my style . The button does a nifty little feature which shows the lowest psi value recorded and the higest value recorded since it has been powered on - great for keeping track of WOT runs. Holding the button for a bit resets it.

0-100PSI Fuel Pressure Sending Unit. Suggested sending unit for that gauge. Since it has one signal and one ground mount, it does not need to be body grounded.

Digital Oil Pressure Gauge. Close look to the other gauge, and most importantly was in stock when I ordered Doesnt have that cool recall feature, but oil pressure is much easier to monitor then fuel pressure and should not be changing dramatically without you noticing anyway!

Oil Pressure Sending Unit. Suggested sending for above gauge. Notice the single signal wire mount - this is why it must be body grounded to the block, just like the factory sending unit. If you use teflon tape make sure to wrap it counter clockwise so it does not unwrap when you screw it in, and do not use too much. If you use the paste like I do, use a small amount. It must be grounded to the block and too much thread sealer may prevent a proper contact for a ground.

You will also need an 1/8 NPT male to 1/8 NPT female elbow to connect the sending unit to the gauge port on your Adjustable Fuel Pressure Regulator. For the life of me I could not find one on summit, but I got one from a local speed shod(American Motorsports). It is "XRP" part number 991401, 1/8 npt 90* elbow. Also, some wiring. I got a three pack of 20 foot wire rolls from radio shack for like 6 bucks - I would buy two of those packs just in case. Each pack has a roll of RED for switched ACC 12v, a BLACK for grounds, and a GREEN which I used as the signal wire(standard signal wire color is YELLOW, but as long as it is a unique color you are good to go). Color coding everything is essential for accurate wiring! If you want the gauges to dim when the lights are turned on(supposedly to be less distracting at night), you should also get some PURPLE wire to wire into the headlights switched power source. If you do not want that feature(I didn't!), just ground the purple wire as well as the black from each gague.

Installing the Fuel Pressure Gauge...

Since every situation may be different, there is no point in trying to explain everything one step at a time. I will tell a basic overview, but it is up to you how and where you chose to run your wires. This is how I did it:

First thing I did was mount the gauge pod where I wanted it and measured out lenghts of each wire. This will vary depending on your AFPR location and where you choose to ground. Mine is on the passenger side rear of the intake but I chose to ground on one of my favorite ground spots - the black wire near the radiator shroud where the fans(i think) are grounded to. Usually a nice clean chassis ground and is conveniently right next to the fuse box - that is also where I grounded my heated 02's during that conversion so I already knew it would work fine. While marking a place to drill a hole through the firewall I was then lucky enough to discover that I had a hole already drilled behind my brake pedal and to the left of it. There is an odd shaped depression in the firewall that there is nothing behind in that area, which was drilled into. A grommet and everything was in place, and a mysterious length of a pair of black and red twisted wire...cut so it was leading to nowhere in the engine bay but up into my ignition. The hole exited behind in the engine bay under the brake booster, in a safe and fairly easy to reach place. It looks like the former owner had a ignition cutoff switch that was removed. I cut the rest of that wire out and tossed it, but gratefully used its hole. I doubt most people will be so lucky, but it is not too hard to drill your own hole. I suggest using a grommet to protect the wire from the metal edges.

After the wire was measured out, I removed my fuel rails/AFPR and took off the 1/8 NPT plug on it. I then screwed in the 90* 1/8NPT elbow using a bit of "Great White" thread sealant paste. My personal preference - it is more expensive then the teflon tape but withstands higher pressures, chemicals, and heat then the tape. It also never hardens or gets pushed out, and is very easy to apply.

Then I screwed in the fuel pressure sending unit using the same paste, and ahead of time attached one end of its BLACK ground wire. This is because in my location it would be VERY hard to reach the terminal with it in place. This is how mine looks installed on my 93, with my regulator in the stock location on the rear of the passenger side fuel rail. 93 fuel crossovers are in the BACK, and there are some differences in part locations but it is all the same thing, just small differences. Note the "custom" bracket I had to make when I installed my AFPR. The factory one doesnt come close to holding the return line, and it was necessary to keep a high pressure fuel like from popping out!

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On the gauge side of things, I wired each pole with the wires already measured out, and ran them through the firewall hole. Remember to go through the gaugepod first! I had the wire already exiting the firewall when I realized the gauge was not in its pod so I had to unsnake and rewire it. Luckily I was by myself with nobody to laugh at me .

I then set the fuel rail with the sending unit installed to the AFPR on top of the intake, and wired the GREEN signal wire that came through the firewall to the other mount marked G. They are supposed to be interchangeable, but one has the ground symbol and the other a G for gauge, so I followed that. Make sure you use some smarts on where you run the wiring. Keep it far as you can from the headers and such, and of course hide it as best you can to make it look clean. Not a single wire can be seen from inside the car on mine, and under the engine bay you will be hard pressed to find any unless you know it is there - take your time!

Now, you can run the BLACK wire's(one from the gauge, one from the sending unit) to whichever grounds you like. I ran the gauge one to the drivers side front chassis ground mentioned earlier, and the sending unit to the identical one on the passenger side.

The RED power wire has to be attached to a SWITCHED 12v source so that it comes on with the key on ACCESSORIES. This is very important so you can check fuel pressure without turning on the car to test bleed down rate(for leaks) and peak priming PSI for pump strength. First though, connect it direct to the positive battery terminal to make sure the gauge works. It will of course show 0 PSI since it is not installed, but that is just to make sure the wiring is ok so far. I used my favorite switched source from the fuse box - the AIR pump fuse. It is not only a heavy duty fuse, but is switched power that gets 12v with the key on both ACC and ON, but not when off. My AIR pump has been deleted for ages, and I had previously mounted my O2's switched power here as well. The fuse is good to quite a bit of amps, and the digital gauges barely use any so if you still have your pump it is ok for the gauges to "share" the fuse. It is fuse #7 on my car, and behind it is a three section power bar that all three get switched power. Of course check with a multimeter to make sure it only gets power on accessories and ON - better safe then sorry.

Once it is tested on the battery then all wired up to the fuse box, You can install your fuel rail checking for clearance on the new obstruction, the sending unit. In my case on my 93, I had to take off a couple threads off the top of the back left stud that bolts the intake down since it was right under the 1/8 NPT elbow. It is just a stud and nothing bolts to it, and can be either replaced with a normal bolt of the same size/thread or just cut the stud off to the head of the bolt. That bastard is fairly hard, so after I removed it and went at it for a minute or two with the hacksaw I grabbed my Saw-Zall and quickly chopped it short with much more pleasure then I should have gotten

With everything installed, go over everything making sure all connetions are tight and sealed. Once you are satisfied, connect the battery and turn it to ACC - DO NOT ATTEMPT TO START THE CAR. The gauge should light, and depending on your fuel pump condition the gauge will reach a certain peak psi then go down a bit. Check for leaks/gas smells right away! If all seems well turn the car off then let it prime again, since after emptying the fuel rails it may not fully prime. It should peak at 40+ psi, and then slowly lower. If it bleeds down to 0 quickly you have a leak somewhere - check the top injector o-rings and the connections you made to the AFPR. If it does not prime very high, then your pump is going! Let it sit for a bit to make sure the pressure does not drop too quickly...

With the vacuum line unhooked from the AFPR, turn on the car. The fuel pressure is factory spec'd to 43.5 under "WOT"(no vac line). 41-47 is all within the range of the computer to still help in adjusting. Depending on your tune and injectors, your build may need more. Adjust the gauge to desired WOT psi, then hook up the vacuum line. PSI should drop ~6-8 psi with the vac line connected at idle with a stock cam. Less drop with bigger cams(less vacuum) ~36 is a decent PSI to shoot for stock cam, but it again depends on your tuner and injectors! Mine only drops 3 psi when I connect my vac line.

If you have any questions/comments/corrections reply here or shoot me a PM!

 

Oil Pressure Gauge

The oil pressure gauge is even easier!

You can use the same 12v source and grounds as the fuel pressure gauge, and there is only one sending unit wire since it grounds to the block through its body.

Follow the same steps as with the fuel pressure gauge and you'll be good to go

I'm lazy right now, will add more details and pics later

If you have any questions/comments/corrections reply here or shoot me a PM!!

 

(Cannot edit above post!)

With the oil pressure sensor, it is important to use the PASTE recommended, not tape. The teflon tape may break off into the engine and cause leaks at the connection, or clog up the sending unit making it inaccurate.

NPT fittings are also very sensitive to how they are tightened. If not perfectly straight it will spin without catching, and if you force it you will just strip the threads. Install carefully!

On a cold idle, your pressure will be higher due to the oil thickening. Once it is warmed up, you should be showing around 20psi at idle depending on its rpms. More importantly, the psi should rise with rpms - around 10psi for each rpms until it reaches its peak value. GM recommends at least 40psi peak, and as low as 9psi at an 800 rpm idle(!) before "needing" servicing. Mine shows around 22-24psi @ 900rpm idle, and WOT goes up to ~52 peak. Not bad for a 160k mile tired old cam'd LT1!!

If your oil pressure EVER drops while the rpms are going up, it is a sign of something wrong. If you reach your peak value while accelerating then it suddenly drops, only to slowly rise again, it is a sign of the bearings going - maybe a spun main, which calls for a rebuild. If your pressure never even reaches an acceptable peak value, the pump can be bad - or the cam or main bearings are still a real possibility.

If you go up in oil weight and the pressure rises a good bit, then it is usually due to expanded clearances. If there is no change, then chances are the bearings are shot - running the motor too much with very low oil pressure can and will spin a main or seize an engine!

This is a finished shot of the gauges in the pods. Sorry for the quality - did not feel like hunting down the digi cam so I used my cell...in the shade of a carport with the sun behind me >.<
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Looks awesome!

 

ooh ..very nice. but i think i like white face analog better.

 

Gauge questions pop up every once in a while, hear is a BUMP to page 1.