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Fuel Pressure Dampener Replacement
 
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Pelican Technical Article:

Fuel Pressure Dampener Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$90 to $140

Talent:

**

Tools:

24mm, 19mm, 17 mm wrench, rags

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

New pressure dampener

Hot Tip:

Work on a cold engine

Performance Gain:

Car runs like normal again

Complementary Modification:

Replace fuel injectors

The fuel pressure dampener is designed to smooth out pulses in the fuel system. Each time an injector fires there is a slight pulse of negative pressure in the system and the pressure dampener is designed to smooth out these pulses and keep the pressure constant.

Replacing it is easy just make sure to use care when working while it is in its mount on the rail. The rail mount is not very strong and prone to failure if you put too much force on it. Make sure to support both the lines and the dampener when working and do not put any force on the bracket.

Be prepared: Work in a well ventilated area. Keep a fire extinguisher near you at all times and know how to use it correctly. No sparks or open flame around and if you smoke now would be a really good time to quit: at least for the half hour it might take you to perform this job.

Just as with the fuel filter, injectors, or any other component of the fuel system, it's best to relieve the fuel system of any pressure before you go opening it up. You can do this by opening the fuel filler cap and/or removing the fuel pump fuse from the car's fuse panel and then starting the car and allowing it to idle until it runs out of fuel. Also, be sure to use some protective gloves and goggles whenever you're working with fuel.

Make sure to wear gloves and proper eye protection. Some fuel will spill out no matter what you do so be prepared to catch it with some rags and dispose of the rags in accordance with the regulations in your area. Never store fuel socked rags anywhere; they are very dangerous.

Locate the fuel pressure dampener.
Figure 1

Locate the fuel pressure dampener. It will be different on some models (turbo, 8 valve and 16 valve). It is always on the fuel rail and most times on the front of the rail (yellow arrow) on the fuel supply line. Make sure it is not the fuel pressure regulator, which will be at the rear of the fuel rail on the return line (red arrow).

To help decrease the pressure in the fuel rail, you will want to remove the fuel pump relay and turn the engine over a couple of times until it runs out of fuel.
Figure 2

To help decrease the pressure in the fuel rail, you will want to remove the fuel pump relay and turn the engine over a couple of times until it runs out of fuel. Begin by locating the relay panel; in earlier cars it will be up under the dash. On the later cars it will be in the rear left side of the engine bay by the base of the windshield. Remove the cover (red arrow).

Check with your manual.
Figure 3

Check with your manual. Locate the fuel pump relay and remove it (red arrow). Crank the ignition over a few times until the car runs out of fuel. Fuel will still escape while performing this job. This will help relieve some of the pressure.

The pressure dampener mounts to the front of the fuel rail; on one end is the fuel supply line (red arrow), a vacuum line (yellow arrow) and a line out to the fuel rail (green arrow).
Figure 4

The pressure dampener mounts to the front of the fuel rail; on one end is the fuel supply line (red arrow), a vacuum line (yellow arrow) and a line out to the fuel rail (green arrow). The line out to the fuel rail actually has a fitting on the bottom of the dampener but is almost impossible to remove it from the bottom. It is much easier to remove the line to the rail and then separate them away from the motor.

Remove the vacuum line by pulling it off (red arrow).
Figure 5

Remove the vacuum line by pulling it off (red arrow). These lines get old and brittle so use care when you remove it.

Support the 24mm nut on the dampener (red arrow) and use a 19mm wrench to loosen the fuel supply line (yellow arrow).
Figure 6

Support the 24mm nut on the dampener (red arrow) and use a 19mm wrench to loosen the fuel supply line (yellow arrow). Fuel will escape so be prepared to catch it and dispose of it properly.

Do not try and remove the dampener from the rail line on the bottom of the dampener.
Figure 7

Do not try and remove the dampener from the rail line on the bottom of the dampener. Instead, remove the line and dampener from the motor as one unit. Use a 19mm wrench and loosen the fitting where the line from the dampener meets the fuel rail (red arrow).

Fuel will escape so be prepared to catch it and dispose of it properly.
Figure 8

Fuel will escape so be prepared to catch it and dispose of it properly.

Supporting the dampener, remove the 24mm nut and washer holding the dampener to the bracket (red arrow).
Figure 9

Supporting the dampener, remove the 24mm nut and washer holding the dampener to the bracket (red arrow).

With the line and dampener removed, you can move the line to the new dampener.
Figure 10

With the line and dampener removed, you can move the line to the new dampener. From there installation is the reverse of removal.










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