Any Advice? Replacing Fuel Distributor Pressure Regulator

[Tidybuoy]

I'm going to replace the Fuel Distributor Pressure Regulator as I think this may be causing the pulsing fuel at very low volume.

The kit appears to come with about 20 shims and I'm thinking that I would replace exactly what my current setup is but I'm wondering if anyone else has done this and does anybody have any advice.

Part I'm Replacing:


Photo of what is included in Kit:

[john walker's workshop]

just match your original setup. a system pressure check afterward would be good. the shims are to adjust the pressure obviously. 4.8 to 5.2 bar.

[LM3929]

to get the inner piston out use a short piece about 1/4 thick by 1 inch long plastic tubing on the end of a bolt or machine screw to draw it out with out damaging it.

Lorne M.

[Tidybuoy]

Thanks! Let's hope I don't goof anything up - it looks like a quick and easy swap.

[HarryD]

Before you do these heroics, question. Did you replace any of the nylon lines with after market parts? Many of the replacement nylon lines have thinner walls and may not be strong enough to prevent the ID from changing as the system pressures change.

[Tidybuoy]

Originally Posted by HarryD

Before you do these heroics, question. Did you replace any of the nylon lines with after market parts? Many of the replacement nylon lines have thinner walls and may not be strong enough to prevent the ID from changing as the system pressures change.

I replaced all of my CIS fuel lines with Coline Hard Plastic Hose. That is, the fuel lines from the distributor to the injectors and from the WUR to the distributor. I replaced the input Fuel Lines with factory Porsche Lines.

[HarryD]

The lines between the FD and the Injectors are most sensitive to ID changes. If the new ones are thinner than the old ones, this may be the source of your surging problem. There is an old post n by me that gives you the correct wall thicknesses.

[Tidybuoy]

Originally Posted by HarryD

The lines between the FD and the Injectors are most sensitive to ID changes. If the new ones are thinner than the old ones, this may be the source of your surging problem. There is an old post n by me that gives you the correct wall thicknesses.

Any chance you (or anyone else) would know the correct sizes. To my knowledge the line was identical to the original but since I changed them over a year ago, I'm sure I don't have any of the old line laying around. I do however, have my receipt from Unobtainum which would state the size that I ordered. I do know that it was pretty think and required the fittings to be pressed in.

Thanks!

[boyt911sc]

Vern,

Do you still observe pulsating flow (initial) with the new fuel injectors? Is this specific to a particular fuel line or at random location? It is quite difficult to assess your problem/s because you are not giving us specific or concrete numbers. We need to know the fuel pressures.

If the primary valve is the culprit for causing this pulsating flow you observed, it would be present in all six (6) injectors. We don't know whether it was the injector or not. Could you do the six (6) injector test simultaneously and mounted side by side?

Why are you replacing the primary pressure relief valve? Have you tested and confirmed it to be defective? Or you just felt replacing it? Keep us posted.

Tony

[Tidybuoy]

Originally Posted by boyt911sc

Vern,

Do you still observe pulsating flow (initial) with the new fuel injectors? Is this specific to a particular fuel line or at random location? It is quite difficult to assess your problem/s because you are not giving us specific or concrete numbers. We need to know the fuel pressures.

If the primary valve is the culprit for causing this pulsating flow you observed, it would be present in all six (6) injectors. We don't know whether it was the injector or not. Could you do the six (6) injector test simultaneously and mounted side by side?

Why are you replacing the primary pressure relief valve? Have you tested and confirmed it to be defective? Or you just felt replacing it? Keep us posted.

Tony

I replaced the primary pressure relief valve due to not really understanding what's causing the pulsing injectors. All six injectors (which are new) are chirping and pulsing when the car is off but fuel pump running. See video below.

Basically, the car runs perfect at highway speed and around town. But at idle it is a little rough. It got better when I changed the injectors and I think it got better with the new pressure relief valve. This weekend, I will do a full fuel pressure test with the CIS pressure gauge tool and report all of the pressures - cold, warm, leakdown, etc.

One thing...when I replaced the pressure relief valve, it came with lots of shims for various applications. My original had one thick shim that was at least double the thickness of any of the new shims so I kept the old. I'm wondering what adjusting the number of shims would do.

Lastly, I bought (on the classifieds) a spare fuel distributor and air flow meter (have not received it yet). I've been concerned about my fuel distributor because I removed it 6 months ago when I was doing oil leak maintenance and the project tool longer than expected. I had cleaned the FD with carb cleaner and then stored in a Ziploc. 5 months later, the piston was frozen. I got it free with ATF/Acetone but I've been concerned that there may be some damage - eventhough it moved smoothly after if got unstuck and the car is running well at speed.

[john walker's workshop]

i posted on your other post about the same thing. with the air filter off and running at idle, see if the sensor plate arm is oscillating. it is visible in the right side of the airbox. the FD is the culprit if it is.

[Tidybuoy]

Thanks! I will take a look. May not be until Friday - it's Halloween and I've got my duties tonight.