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© 1998 Brian F. Schreurs
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Too free up some more fuel, we decided to pony up to an adjustable fuel pressure regulator. And if you're going to be fiddling with the fuel pressure, it helps to have a gauge. We couldn't find an interior gauge for a fuel-injected car (requires an isolator) so we bought a regulator/gauge kit from Some Guy who really came through for us. He sent an Aeromotive adjustable fuel pressure regulator (#131-02-B), all necessary fittings, and a custom-built steel braided fuel line. We got the gauge from AutoMeter (#5412), which required their mounting bracket (#5202). Mounting the gauge will require some miscellaneous hardware from Home Depot Racer's Supply.

For starters, have a friend set the gauge on its bracket and hold it on the cowl. Then sit in the drivers seat and have him move the gauge around till it's where you like it. When you find the right spot, use a pick to scratch a couple of X marks in the bracket bolt holes.

Here's the work area for installing the fuel gauge, with the cowl removed.

Time to take the cowl off! Start by removing the windshield wipers. They are held in place by -- get this -- one pin each! The pin is located at the base of the wiper, on the windshield side, and simply pulls out about an eighth of an inch. Ta-daa, wiper in hand! Kinda scary if you think about it. So don't.

With the wipers out of the way, the cowl just pulls off like most plastic pieces these days. Start on the driver-side, and when you get to where you can see under the cowl, have a look at where you marked the bolt holes. You'll be running bolts through them so check for interference, particularly from the seam of the inner fender. If there is a problem, push the cowl back in place and try another position. Once you have a final position, completely remove the cowl.

The gauge mounting bracket is successfully mounted.

Drill the mounting holes. Don't make them any bigger than what you need to put the bolts through.

We tried drilling a hole through the inner fender as a secondary mounting point but ran into problems. Since our gauge seems fine without it, we advise to not mess around with a secondary mounting point.

Mount the gauge bracket to the cowl. Use decent-sized washers to distribute the load on the plastic cowl.

Attach the gauge to the mount. Make what few adjustments the mount allows, and tighten. Then tighten it again.

Here's the clever way to route the wires through the fender.

It's time to wire up the illumination! First, where do the wires go? We already had wires ready for this gauge, because we've previously installed an Oil Pressure Gauge and a Transmission Temperature Gauge. But here's what you need to do:

The illumination wires need to tap into power and ground for your parking lights. We cut out the middleman and went straight to where we knew the circuit would be the way we wanted: we spliced into the wiring harness at the front-driver parking light.

If you want to do it our way, lift the plastic flap covering the driver-side headlight. From there you'll be able to access the bolt (sorry, we forgot to write down the size) that holds the side light in place. Then just disconnect the wiring harness from the housing. As usual with these darn plastic clips, they're brittle and likely to break. So be careful.

Use a blade to cut away some of the plastic insulation, then use a multimeter to determine which power wire is the parking lights (you don't want your gauges to blink with the turn signal do you?). Run the illumination wires out to the harness (through the inner fender and along the inside driver-side edge of the engine bay) and splice the power wire into the harness. Then put the insulation back on and tape everything up.

The original fuel pressure regulator (hose removed)...

...and removed. Watch the O-ring.

The ground wire can ground on one of the green screws just next to the battery, on the radiator support. Easy. Then put the marker light back together.

Put the cowl and windshield wipers back on. It is possible to put the wipers back exactly the way they came off, but it may take some fiddling to do it.

Now it's time for the engine side! First, relieve the fuel pressure. It's easy for us -- we have a fuel cutoff circuit on our car. If you don't have one, you can get similar results by pushing the pin in the Schraeder valve, on the fuel rail. Or just let the car sit for about an hour. If you've just finished installing the fuel pressure gauge, it's probably been at least an hour!

Find the fuel pressure regulator. It is located on the passenger-side of the engine, behind the throttle body. There is a vacuum hose leading off it, and it's held in place by two hex key bolts, size 5/32.

Pull the vacuum line off and unbolt the regulator. Fuel will spill. Not much you can do about it really, except mop it up with a rag. That's just part of working on a fuel system.

When you try to remove the regulator, watch out. There are two fuel ports on the bottom of the regulator, and one of them has an O-ring that is critical. The new regulator doesn't come with a replacement. Pull the regulator off gently and keep an eye out for the O-ring; it's orange. Save this ring and put it back in its seat during reassembly. We didn't know about the O- ring until our regulator doused the engine in gasoline on startup. Then we spent two hours trying to find and retrieve it.

When you have the regulator carefully removed, save the O-ring (has this been drummed into your head yet?) but chuck the regulator. You don't need it.

Get the nice new adjustable fuel pressure regulator (AFPR from now on thanks). Prep it for installation as follows:

This is the new Aeromotive piece, ready to go.

Remove the plug in the fuel gauge outlet. It takes a 3/16 hex key. Replace it with the AN elbow fitting. Attach the stainless steel fuel line (it's a tight fit on the engine so it's easier to do it now). Of course, use thread sealer on all piping.

Install the vacuum fitting in the vacuum port.

Put the new AFPR on the engine. It should only fit one way: vacuum on driver-side, fuel on passenger-side. Remember to put the orange O-ring back under the AFPR or you'll be in a world of hurt when you start the engine.

The new unit installed.

Install the vacuum line. It may fit a little loose. Use a hose clamp if you can; Home Depot Racer's Supply was closed when we needed one so we just tried to jam it on real good. So far it's holding.

Route the fuel line to the gauge. Our line was custom built, three feet in length, with a 90-degree fitting at the gauge side. We ran it along the back of the engine next to the firewall, then up through the driver-side hood hinge weatherstripping. From there it exactly reached the gauge. Attach the line on the gauge side.

How to route the fuel line around the hood without drilling any holes!

Start the car and check for leaks. The car may be hard to start, and may run poorly. This is because the AFPR is not set yet -- it could be at almost any pressure (especially if you were fiddling with it beforehand, and come on, you know you were). But it should run well enough for you to quickly check for leaks.

Of course, if there are any leaks, shut off the car and fix them.

With any leaks fixed, it's time to adjust the pressure. Get the car running and remove the vacuum line to the AFPR. The adjuster is right there on top; it takes a 9/16 wrench. Clockwise (rightey- tightey) increases pressure. Start by adjusting to 40 psi. This will keep the car running nicely. Now put the vacuum line back on and take it for a test drive. When you get back check for more leaks.

If it's all hooked up without leaks, and the lighting works, you're done!

Yeeha! The gauge is installed!

The 40 psi is a good guesstimate. Each car has its own needs based on the car's parts combination. How do we figure out where to set it? There are a couple of choices.

First is the seat-of-the-pants, or SOTP, method. This method sucks. Don't use it. Another choice is to buy a G-Tech and use its accelerometer to fine-tune the fuel pressure. This method is acceptable but requires buying a $140 piece of equipment and a quiet road where no one will notice repeated acceleration tests. The third option is to rent dyno time. This will produce the best results but tuning time is expensive. Finally, go to a track test-n-tune and do it there! Cost will be around 20 bucks and there won't be any worries about disturbing the peace. Plus it's fun! It's definitely the best way to go; that's how we'll tune ours.

Postscript: After a week the AFPR self-destructed. This is identifiable by the failure of the car to start without pumping the gas pedal and gasoline dribbling out of the vacuum line. We sent it back to Aeromotive under warranty; it took them a while to return it, since apparently they were totally reengineering the internals, but when we got it back it worked flawlessly. We've had no problems since.

The new BBK regulator.

Post-Postscript: Until now! Oooh, we're steamed. Why is it so difficult for these people to build a regulator that works? About two and a half years after the original install, the redesigned Aeromotive regulator self-destructed. Not wanting to deal with them anymore, we bought a Paxton regulator. Well... guess who reboxes Aeromotive regulators.... After that one also proved faulty, we moved on to a BBK regulator. It seems to be working okay, although the pressure doesn't adjust downward to stock levels (not that we want it at stock levels anyway) and one of the vacuum lines has to be bent pretty bad to make it fit. We intend to replace this unit with a Kirban. All reports are positive on the Kirban unit; the only drawback is that we'll have to reroute the fuel pressure gauge line. No big deal.