1984 280e Fuel Distributor Flow Adjustment Question - PeachParts Mercedes-Benz Forum

ccb_v2 · #1 11-17-2021, 02:31 PM

Hi there. Quick question about the adjustable screws (part 730...ish six of them) that move the six sleeves controlling the flow rate up and down. How far into the distributor should they be when measured from the cap screw's distributor mating surface? What should their depth be or is there a certain amount of fuel that it should pump out a WOT and idle that I can measure to try and set it?

porkface · #2 11-18-2021, 08:51 AM

this is why i get my parts from cisflowtech. he flow tests them and knows what to do. yeah, he's slow and expensive but it's right. good luck, chuck.

ccb_v2 · #3 11-24-2021, 06:32 AM

Does anyone have the WOT flow rate for a 1984 Euro 280e? I've done the flow test on a W124 where you jump the fuel pump via the relay and measure how much fuel flows at WOT from each injector, but how much fuel should be getting dumped into the six bottles?

Dave Kost · #4 12-09-2021, 10:06 PM

I was going thru some documents and ran across this article.

Maybe it can point you in the right direction.

locry · #5 12-09-2021, 11:18 PM

Dang that's hardcore adjustment territory!!!

I'm going through the same thing. I managed to get the fuel flowing through the injectors via the flap... but after a day of testing, I'm not getting any fuel through the injectors. I've rechecked the fuel flow like you, but I'm stumped as to why it seems i'm not getting any pressure. Did you encounter this issue at any point?

ccb_v2 · #6 12-10-2021, 07:04 AM

Exactly where I am. I have fuel flow at the top of the distributor but not enough pressure it seems to spray through the injectors with the pump relay wired to run via a remote switch. There is a valve that goes into the bottom that I guess controls fuel pressure in the distributor, not sure if that is the culprit...

There's one at the top as well:

Dave Kost · #7 12-10-2021, 09:44 AM

That looks like the fuel pressure regulator on a K Jetronic car. Totally different system from the KE Jetronic. Do you have a warm up regulator?

First you need to test your fuel pressures. Everything else is a guess to solve your problem. The basic K or KE Jetronic is based on fuel pressures being in spec.

System pressure
Control pressure - if (K Jetronic)
Fuel volume test.

Are they in spec? Do you know the spec? Sorry I don't, but maybe someone here will know.

ccb_v2 · #8 12-10-2021, 11:30 AM

Those two pics are what I had in this FD when I cleaned it. The long one in the bottom half which per an old VHS capture on YouTube is to regulate fuel pressure inside the FD, the other is at the top and not sure what it does. This FD came off a 1984 280e, but a euro car... I'll see what google can tell me when it comes to checking the fuel pressure on the line with the pump running.

ccb_v2 · #9 12-10-2021, 11:38 AM

Quote:

Originally Posted by Dave Kost

Do you have a warm up regulator?

Based on what I see looking from up top I think there is, I see a fuel line that goes down to the block maybe from the pressure regulator and another line that comes from down there and connects to the FD. These lines seem to attach to something that is on the engine block it seems.

Dave Kost · #10 12-11-2021, 07:04 AM

Im not an expert on the 280E but this is my educated guess. You may want to check the 123 forum in BenzWorld.

The top picture in post #7 is the pressure regulator. It controls the system pressure. It is adjustable by shims.

In the top picture in post #8, the small cylinder with the electrical connection, is a Frequency Valve. It is controlled by a ECU that reads the voltage of a O2 sensor.

It works similar to a EHA valve in KE Jetronic in that it controls fueling to the injectors by leaking fuel back to the fuel tank.

The ECU is controlled by a relay. If the relay is not working, the ECU can't control the FV and you will have all sorts of running problems.

So the first thing you check is if the FV is working. It should vibrated when the car is running.

ccb_v2 · #11 12-23-2021, 07:30 AM

Quote:

Originally Posted by Dave Kost

Im not an expert on the 280E but this is my educated guess. You may want to check the 123 forum in BenzWorld.

The top picture in post #7 is the pressure regulator. It controls the system pressure. It is adjustable by shims.

In the top picture in post #8, the small cylinder with the electrical connection, is a Frequency Valve. It is controlled by a ECU that reads the voltage of a O2 sensor.

It works similar to a EHA valve in KE Jetronic in that it controls fueling to the injectors by leaking fuel back to the fuel tank.

The ECU is controlled by a relay. If the relay is not working, the ECU can't control the FV and you will have all sorts of running problems.

So the first thing you check is if the FV is working. It should vibrated when the car is running.

The injector buzzes with the key on and during start-up attempts. Guessing it is the pressure regulator valve which makes sense if there isn't enough built-up pressure to push fuel through the injectors. The question is do you add shims (washers) to increase it and how many. I don't think I have a fuel pressure tester that fits the metric threads to try and hook a meter up. Ugh.

Frank Reiner · #12 12-11-2021, 04:16 PM

OP, DK:
It may be worth noting that the O2 feedback system that includes the frequency valve is an aftermarket lashup that was installed on grey market cars to soothe the EPA. It affects the control pressure, but can only adjust in the rich direction (by reducing control pressure). In contrast to this aftermarket device, the OEM K-Lambda system adjusts the lower chamber pressure in the fuel distributor, and can both lean and enrichen the mixture.