3.2 Fuel Pressure Gauge

[BoxsterGT]

I have been working on a replacement 3.2 Fuel Pressure Regulator that won't break the bank as the factory originals at $400 each now do.

It is "Modular" and uses a FPR similar to the ones used on the 993 motors.

While researching this I realized a Fuel Pressure Gauge was necessary to confirm /verify the Fuel Pressure settings.

Here is what I have come up with.....



I have made up a custom Adapter to mount this Oil-Filled Gauge to the Left Fuel Rail Test Port. It is available in PSI or Bars scale and is reasonable in cost.

For anyone interested in either this Gauge or the Fuel Pressure Regulator or Fuel Pressure Damper made specifically for the 3.2 motor, please email me.

len.cummings @ verizon.net but without the spaces.

Thanks for looking.

Len

[BoxsterGT]

Forgot to add that I also have a Remote extension for this Gauge.....



....so that on a temporary (TEST ONLY) basis you may evaluate the fuel pressures while road testing.

Per Porsche 964 Service bulletin:




I MUST EMPHASIZE THIS IS FOR EVALUATION ONLY AND ON A TEMPORARY USE BASIS AND NOT FOR LONG TERM.

For long term use this must be electrical, with a 12v sender and gauge.

Len

[Cherry Bomb]

Is the gauge in connected via rubber hose to barb fittings?

[BoxsterGT]

The remote version shown is for Polyamide tube only.

I do have fittings for Rubber hose if needed but do not have the small 4mm hose needed.

For info, email me: len.cummings @ verizon.net but without the spaces.

Len

[BoxsterGT]

Bump to the Top....

Len

[Mr. Merk]

Len, what did you come up with for the diaphragms? Currently in need of a set! Porsche is now about $685/ea

[BoxsterGT]

Mr Merk-

Best to email me so I can send you photos.

Len

[scarceller]

The most important thing that the regulator MUST do perfectly is maintain 36-38PSI across the injector.

Notice I said "across the injector" this is most important to understand. The injector is injecting fuel into the intake plenum that's under vacuum. It does not inject into atmospheric conditions!

This is why we have a vacuum hose that provides the fuel regulator with a reference reading of the vacuum in the intake.

The regulators job is to regulate the pressure at 36-38 PSI above the intake vacuum.

For the injector to be accurate it MUST have the speced pressure of 36-38PSI across the injector.

Hopefully that makes sense.

[scarceller]

Harbor Freight sells a fuel pressure test kit with correct fittings to mate to the 3.2 fuel rail. It's the more expensive kit they sell.
Part number SKU: 58817
This kit also has everything you need to test CIS injection!

[BoxsterGT]

Sal-

I am about to pressure test my new Modular FPR and Damper set I am putting together.

Can you advise me on connecting a vacuum source to the Regulator?

The only FPR unit I can buy at a reasonable cost is an adjustable one, so I must set the pressure at 37psi +/-.

Must I have a vacuum signal to the Regulator? If so, at what level?

Thank you for your expertise in these matters.

Len

[eastbay]

Originally Posted by BoxsterGT

Forgot to add that I also have a Remote extension for this Gauge.....



....so that on a temporary (TEST ONLY) basis you may evaluate the fuel pressures while road testing.

Per Porsche 964 Service bulletin:




I MUST EMPHASIZE THIS IS FOR EVALUATION ONLY AND ON A TEMPORARY USE BASIS AND NOT FOR LONG TERM.

For long term use this must be electrical, with a 12v sender and gauge.

Len

No knock on you Len, but I guess Porsche must have got a new guy that was unaware of the old polyamide repair methods when they issued your reference TB. BTW, I have used this official Porsche repair manual method successfully many times.

Of course, not telling you anything since you make them. Just thought the TB was humorous

[BoxsterGT]

Lot's of great information from Porsche AND those who have done this and posted here on our Pelican forum.

The one thing I have learned (sometimes the hard way) is the orientation must be correct, as these Polyamide tubes cannot rotate or twist to reach their destination.

Years ago I had to make up fixtures from original lines so the orientation could be made as factory.

Len

[BoxsterGT]

Mr. Merk-

Here is the much more reasonable in cost Modular 3.2 Fuel Pressure Damper........



that replaces the expensive factory original. Could not find a sealed FPR and had to go with an adjustable version.

For information, please email me only. No pm's as we cannot send photos via pm.

len.cummings @ Verizon.net but without the spaces.

Thanks for looking.

Len

[76FJ55]

I'm not saying you'll necessarily see any performance issues, but one thing to keep in mind on the fuel dampers is the drop in units are designed for sequential fire injection, so the volume displacement of the damper is much smaller that the original damper on our cars due to the nature of our batch fire system.

For the drop in style fuel pressure regulator to get the correct injection pressure take a look at Bosch part # B280.550.340-03. this will be the adjustable FPR from 2.2-3.5 BAR and will also have the correct vacuum port for connecting the manifold vac line to maintain the differential pressure between fuel and intake.


https://www.bosch-motorsport.com/content/downloads/Raceparts/Resources/pdf/Data%20Sheet_68005387_Fuel_Pressure_Regulator_Mini _A.pdf

[BoxsterGT]

Thank you 76FJ55. The more info we have the better.

Once these are road tested we will know.

Having a Pressure Gauge for setup will help.

Having a vacuum connection and the adjustability of the Regulator should help as well.

I asked scarceller about the effect of the vacuum signal but no reply yet.

Len

[76FJ55]

The vacuum source for the regulator should come off the intake manifold. the intent is to maintain a constant pressure differential between the fuel and intake manifold pressure. Essentially the spring in the pressure regulator sets the base pressure (gauge pressure) and then you connect the manifold vacuum source to the regulator to the side opposite the fuel. Since the vacuum and fuel are on opposite side of the same diaphragm any change in manifold vacuum is immediately balanced by the same change in fuel pressure (force x area = pressure).

[76FJ55]

I don't know your manufacturing cost or marketing price point, but just an FYI, housings for these exact regulators and dampers are already available on the market, that are compatible with the Carrera 3.2

[76FJ55]

BoxsterGT, I tried sending you a PM but it seems your mailbox is full.