K-Jetronic Specialists

11/11/2025

I received an email this morning with a question about the 'upgrade' to the WUR he had purchased. This is my response.
This is not an upgrade and I would carefully loosen the lock nut and unscrew the the screw to remove it.
At some time in the past someone had a problem with the pressure in their WUR and decided that they could change the pressures by pulling the bimetallic strip up, or pushing it down. There are a number of problems with this stupid idea.
1. If the bimetallic strip post turns and is no longer in perfect alignment under the fuel cell, then the WUR cannot function correctly at all.
2. If you don't have fuel pressure gauges attached how can you possibly know where you are setting the pressures to?
3. The bimetallic strip function is there to change the pressures when the engine is cold, and so for the first 2 or 3 minutes after start up. If the WUR has been set up correctly the warm pressure is set by moving the fuel cell down until the correct warm pressure is met. When the WUR is warm the bimetallic strip has almost no affect on the warm pressure.

04/11/2025

Received this nice email from Mark in the UK, today "can you send me the link for you reviews page....I am planning to install it all at the end of next week, but I am so impressed by what you have done and the speed with which it has been done......quite simply I cannot see any reason why anyone anywhere should get anybody else to service these components. You have got this totally buttoned up and I would like adding my name and location to the other delighted customers!

27/10/2025

Anybody in the Brisbane/Gold Coast area with a BMW E3, E9 with D-Jet injection. I need to test a MPS sensor, so I just need to pop the bonnet plug in my MPS and check the car starts and revs ok, maybe take a set of readings from your MPS to compare, would take less than 30 minutes.

27/08/2025

Kugelfischer pump clear back cover to help us check everything working correctly while on the test bench and running at various speeds.

01/08/2025

I have finally found the time to get the system pressure valve push rod seals made up
The original ones are molded onto the push rods and are hard to remove. I put the push rod into a drill and used a scalpel to cut away the seal while the drill slowly rotated the rod. Once cleaned up, a little bit of Vaseline on the rod and seal, slipped it into place and it worked perfectly.
I will be selling the seal with a 10mm copper washer for the end cap for AU$5.00

05/04/2025

Inventive yet crazy. Opened up a 0 438 100 034 Ferrari fuel distributor to find a homemade plastic diaphragm. Why would you go to so much effort when they are available in our kits?

05/04/2025

Very satisfying to finally finish the reconditioning of a Pierburg DL system from a rare 1987 BMW B7 Alpina (B28). We needed to have diaphragms made and it was quite a challenge as teir is so little information on the system.

19/02/2025

Another Mercedes pump ready to leave the workshop

19/02/2025

Someone had an issue with fuel below the fuel distributor and disassembled the FD and found scoring on the piston. This is my response to them.
You are correct that fuel should never leak out the bottom of the FD. Usually the problem which causes scoring on the piston and barrel is the roller below the FD in the air flap no longer spins freely and so it tries to kick the piston to the side and causes the piston to grab in the barrel.
Pistons and barrels are not generally available so you need to clean up yours. The important thing to remember is that the clearance between the piston and barrel is so fine that fuel molecules are not able to pass between them.
The only way to clean it is with a dish washing pad, not too harsh, and brake cleaner and carefully polish it. You will not remove all the marks, so don't even try to get it perfect, you are only removing the worst of the roughness.
Once i is a bit clean, spray the piston with silicone spray and it should slide up and down in the barrel, but not be loose.

04/02/2025

Although our WUR rebuild instructions are available on our web site www.k-jet.biz it seems that some people still have trouble setting up their WUR. This is the basics for the average double diaphragm WUR.
If you have the plug out of the bottom of the WUR, turn it anticlockwise to the bottom and then clockwise 2.5 to 3 turns clockwise.
You need to also have the bimetallic strip pin pushed up level with the top of the WUR.
Run the fuel pump to measure the WUR control pressure and give manifold vacuum (approx 14"hg) to the large (8mm) tube on the side of the WUR
The pressure you want is 3.6bar. If it is low, you can either tap the fuel cell down a bit until you get to 3.6bar or screw the Allen screw in to get 3.6 bar.
If the pressure is above 3.8bar, turn the screw anticlockwise to bring the pressure down to 3.6 bar. If you can't get it low enough your fuel cell is push in too far.
After you have 3.6 bar with vacuum you need to remove the vacuum and the pressure should drop to less than 3bar.
Now fit the base plug in and gently tap the base plug in until you get to 3 bar.
Refit your vacuum hose and you are back to 3.6bar.
Now you can gently tap the bimetallic pin down until you get to the correct cold pressure for the ambient air temp.
Now fit the electrical plug on the top and the pressure should raise to 3.6 bar in approx 3 minutes.

Please email me about anything you need or want to know. I have lots of parts including exchange reconditioned Fuel Distributors and Warm-Up Regulators available, Auxiliary Air Slides, Auxiliary Air Valves, D-Jet Manifold Pressure Sensors, Mechanical fuel injection pumps and much more for your class...

16/07/2024

I see lots of interesting things every day, but this makes me a bit angry. This WUR was 'professionally' rebuilt. It came to me as it still wasn't right. The rebuilder cut the rivet tops off and drilled into the side to lever off the small diaphragm end plate, then, after replacing the small diaphragm used a resin glue to hold the plate on. On the other side the rebuilder must have used a grinder to separate the main gasket, and has then glued it back together,

25/02/2024

Fuel cell end plates. The smaller centre 'hats' are typically found in WURs fitted to Porsche