Do I need the small dampner on the pressure side of the fuel

[blues90]

Pump ? It's still there and does not leak but if it serves not real important function then all it does is add more fuel line in the system.

I'm not sure if anyone still has theirs on their car . I know no one makes or sells them of even how good mine is other than it looks like just an open round small can with two nipples on it.

I guess it damps the sound of the pump and I've always had it there. Can't say if I'll hear the pump without it or care unless it makes some great difference.

[KTPhil]

Many here run without it and report no problems. I have mine, but I have no idea if its damping anything or not after 38 years.

[JSMskater]

I'm still running mine. I blew it out with compressed air.
_________________
71 Squareback-FI -- 70 Ghia --73 Bay
TOOB Member #3
I make D-jet FI Harnesses!
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[raygreenwood]

There is not one part in this system that is not important.

Yes, you could run without it (but you shouldn't), because it is designed to do something specific. It gets rid of a peculiar harmonic that happens at certain fuel usage levels. This harmonic can cause serious pressure fluctuations at the injector level.
You have to bear in mind that the roller pump is like a very slow (relative) version of a turbine. Fuel comes in and is compressed between the rotor with open cells in it...and the rollers contained within those cells.
Its the best type of pump for pressure, voulme and reliability....but...it has pulses as each cell passes the intake point..compresses as it travels around and has a release point as it dumps into the outflow. Depending on the rpm of the pump...this happens many times per second or per minute.

If fuel pressure is high or normal and usage is low...like at idle or low speed....the relief valve and the spring diaphram of the regulator keep a tight "loading" between each of these pulses and they are virtually unnoticable .....unless volume is improperly low.....which brings us to the next condition......where you are accelerating and using fuel rapidly....which means you are removing fuel from the ring main rapdily.

This unloads the pump and the rotor....the regulator clamps down to maintain pressure..and the pump pulse spacing gets unloaded......and the pulsing gets noticable.....to the diaphram in the fuel pressure regulator which will begin pulsing and fluctuating rapdidly. This is very destructive to the regulator.

Those who claim to have no problems without this pulse damper...have no idea if that is true or not....sorry...no offense.

You would have to have your head inside of the engine compartment close to the regulator to hear it....and a gauge on the ring main to see it....while you drive.

But everyone who does not have this pulse damper...has this problem. It makes the exact same sound that you hear in the morning when you first start up when the air is being chased from the system....it is a "honking" or horn sound. You can't hear it when you are running at speed.

Those who have basic stock levels of tuning (slightly richer than ideal but satisfactory) will see slight levels of throttle response loss as the system struggles to maintain fuel pressure for that instance of acceleration while the diaphram flutters.....and for those who have their system tuned out better and leaner or are modified....you are risking putting a hole in the piston one of these days at peak rpm and max advance.

And....don't argue about this.
Most people have no idea how that crummy little part actually functions.....and do not do the testing to see what it does...and for that there is no defense. It took me a long time to find out (had to ask an engineer)....and until then I ran without one numerous times.

It was not until I started doing fuel pressure testing at speed on D-jet that I found the problem of unstable fuel pressure. That little do-dad fixed a portion of it.
It actually works worse the closer it gets to the injectors..........for the same reasons that modern VW's and some other cars are now regulating their pressure at the tank and fuel filter and doing fine adjustments only....at the fuel rail. Thats a later discussion.

The reason you don't need one on some or "most" L-jet? Because they are more similar to the common pumps now....called a vane type or peripheral pump..though they are still roller pumps.. They do not create the same level of pulses. They have an internal over-pressure relief valve like D-jet pumps...but also have a non-return valve that helps damp pulses...as well as feeding the fuel through the pump body as coolant that helps damp pulse...and the rotor ring design is slightly different.
http://bama.ua.edu/~darren/bosch/Page08.html
Ray