Are you writing about the fuel pressure regulator, the goldish canister?

 

I didn’t know there is a filter in the FD inlet line. Is it just a metal mesh? Could it be improper in some way or clogged somehow? Perhaps try running without it, as the upstream fuel filter at the pump cluster should be effective on its own.

You say you loosened the injector lines to purge any air. Did fuel weep from all the junctions? If not, perhaps some debris entered the FD when you removed the old filter?

You say there is fuel pressure. Did you actually measure it to see if it meets spec?

I dont see any movement in the intake plate until you push the pedal. I believe it should open slightly when you crank the starter.

Sometimes there are multiple coincident faults in old cars. Something else unrelated to your filter change may have occurred by chance. It certainly presents as a fuel supply problem but I would pour a little fuel directly into the intake to confirm.

 

@jsebastian, No about the fuel distributor, the spider.

@dugald, The new filter is good. Didn't measure the actual pressure, as I don't have the meter for it, but when I unscrew the inbound fuel line from the FD gas quits out, so I don't think it's the fuel pressure.

I just watched the below series on YT, he purges the lines from FD to injectors as well, I try that tomorrow as well as checking the intake plate.

 

Curious, what happens if you put the old filter back on?

 

@bauk .. what are you highlighting in the parts schematic #50?

 

@dugald: that is the filter fitting I replaced. (A 000 074 60 86)

 

I didn't know there was a strainer in that fitting.

 

Were you able to get the car running?

 

Yes when starting the engine with full throttle and keeping her above 2000 rpm, she would run. As soon as I let her drop below 2000 rpm, the engine dies out instantly.

Yesterday I purged air all the way up to the injectors 2 by 2, all injectors receive gas, but no damn start unfortunately.

 

Seems unlikely that it has been affected by a simple fitting swap, but I think you may have to try adjusting that intake plate.
Do it in much smaller increments than that bold fellow in the YT video and remember where you started so you can return there if it doesn't work.

 

A Mystery! I agree with Dugald. The plate looked "closed" but why would it be different from before? And thanks for the filter info. I had no idea it was there. Wishing you a fast solution. Please keep us posted:smile

John

 

Agreed, Dugald is on the money.

I would first make sure you're actually getting the right amount of fuel pressure. Maybe Murphy paid you a visit and something is causing the pumps to pump less.

One tip I may add, unbolt the injector hardlines and adjust the air metering screw until you reach the point that fuel dribbles out of the top of the ports.

Then hook everything back up and see if it starts. The car should fire up, but you'll need a duty cycle meter to dial it in further.

 

Ok, thanks guys. I am going to follow that route. This YT movie also points in the same direction.

I don't have the car next to my home, so I'll refer back to you guys in the weekend.

 

Didn't have much time last weekend, but did a few test and it I start to have the feeling that there might be not enough fuel pressure to make it all the way thru the FD to the injectors.

I ordered and fuel pressure gauge to obtain a reading, but the have the fuel pumps running constantly is there really only one way to jumper them by diving deep into the dash and jumper pin 30 with 87? No easier way?

 

Hello Bauk18,

I‘m actually not active in this forum … I just wanted to browse a little in it and the first thread at the top (this one) caught my eye.

I suggest the following:

1.) Check if the air flow meter plate moves (about a centimeter or so) away from it‘s (correct) rest position when you (try to) start the engine, and check if it moves further down if the throttle is completely opened during starting.

2.) If that‘s the case, check the fuel pressure … “system pressure“ (SP) and “lower chamber pressure“ (LCP).

... I start to have the feeling that there might be not enough fuel pressure to make it all the way thru the FD to the injectors. ...

Assuming that there were no issues before you replaced the FD filter fitting, there might be too much fuel pressure … in the lower chambers that is. … With ignition off and fuel pumps running, LCP shoud be at least 0.3 bar (4.5 psi) lower than SP.

If the difference is smaler … and I‘ll have enough time … I‘ll explain a possibly helpful next step.

If that step will be successful, I‘ll tell you what happend when you replaced the FD filter fitting. … :wink_2:

H.D.

 

You can jump 12v directly to the fuel pump terminals.

Did you ever try putting the old filter fitting back in?

 

Did you ever try putting the old filter fitting back in?

Yes, no difference. I have fuel on the cold start valve, but not on the lines to the injectors, so I am suspecting that I don't have enough pressure to push the fuel thru the FD.

 

Danke shön H.D! I have a pressure meter underway, estimated delivery end this month, so I'll get back to you asap op step 2. On step 1 I'll make a movie later today and post it.

 

The air flow plate moves when starting and it moves deeper when throttle is further open.

 

The air flow plate moves when starting and it moves deeper when throttle is further open.

Okay … next on the to-do list: the fuel pressure test as described in my last post.

I wouldn‘t have noticed your last two posts if I wouldn‘t have visited this forum again. I didn‘t receive email notifications about them … happens often … :dunno:

H.D.

 

Finally found time to test both fuel pressures. I first did the top chamber, see as well first movie, fuel pressure is 6 bar = 87 psi.

I checked as well if the system holds pressure for a longer time and this is the case, 3 bar for more then 20 min.

In the 2nd movie you see the lower chamber pressure is 5,2 bar = 75 psi. A difference of 0,6 bar or 12, psi.

Does this point us in a direction?

https://www.youtube.com/watch?v=VaII38VAIGg&frags=pl,wn

https://www.youtube.com/watch?v=88MDm1c-230&frags=pl,wn

 

... I first did the top chamber, see as well first movie, fuel pressure is 6 bar = 87 psi.
I checked as well if the system holds pressure for a longer time and this is the case, 3 bar for more then 20 min. ...

If that‘s what you measured at the CSV port, it‘s the system pressure (SP), which on your car should be between 6.2 and 6.4 bar. It should drop to 3.4 bar when the fuel pumps stop running. What I see in the first video points to a problem either with the pressure gauge or with the fuel pressure regulator.

... In the 2nd movie you see the lower chamber pressure is 5,2 bar = 75 psi. A difference of 0,6 bar ...

That‘s during cranking. But (in post 18) I suggested to check LCP “with ignition off and fuel pumps running“.

You can alternatively check LCP during cranking, but with the EHA plug pulled off !

 

Tested again the system pressure and lower chamber pressure, but this time with EHA unplugged.

The system pressure was again 6 bar. The lower chamber pressure was 0,2 higher on 5,4 bar.

What could it be?

https://www.youtube.com/watch?v=SbqqmU8iNZc&frags=pl%2Cwn

https://www.youtube.com/watch?v=zKrOiEtADJk&frags=pl%2Cwn

 

From what I can see in these last two videos, LCP is about 0.5 bar lower than SP. That‘s still okay. However, the general pressure level is a bit low, which, as I said in my last post, points to either a problem with the pressure gauge or to wear in the fuel pressure regulator. But that is not the reason for the symptoms you describe.

Assuming that there were no issues before you replaced the filter fitting, my first suspicion was that some dirt particle(s) got into the FD when you changed that filter fitting and clogged the FD‘s restrictor. That can easily happen when the filter fitting or the EHA is changed and it can be quite a lot of work to fix that.

But - provided that your EHA adjustment screw has never been touched (turned clockwise) - your fuel pressure tests show that your FD‘s restrictor is not clogged.

However, dirt particles can also impede the control plunger‘s movability. That‘s why I suggested step 1 in post 18 whereupon you made a video of the AFM plate's movement during cranking. From what I can see in that video that does not seem to have happened either. However, you might want to do an additional AFM/CP movability test as described in the following thread (post 22):

https://www.benzworld.org/forums/w126-s-se-sec-sel-sd/2780778-who-knows-3.html

H.D.

 

Thank you HD for your help!

I read a lot about the Bosch CIS system the last couple of days and decided that I have too many variables at this point. As my SP is 0,2 bar lower then it should I have no history when or even ever the fuel pomps have been replaced + filter I decided to buy those new and take if from there.

More in the next two weeks.

 

Installed the new fuel pumps and filter today, but still no success. The engine wants to start the second after ignition, but only for a very brief while, see video.

I really don't know what to do anymore.

 

It that fitting a check valve? Maybe it is defective.

 

No it's a simple little filter, but I wished I had never touched it...

 

I think the engine is firing on fuel from the cold start injector only.
It’s getting nothing from the other injectors. I suspect the FD is clogged, despite @H.D. diagnosis in post #26.
Can you nurse the engine into continuous operation by dribbling fuel into the intake?

 

... I suspect the FD is clogged, despite @H.D. diagnosis in post #26 ...

If you read post #26 attentively, you may realize that I said: “... your fuel pressure tests show that your FD‘s restrictor is not clogged.“

I did not say that the FD is not clogged. On the contrary, dirt having gotten into the FD is still a suspicion I have … which is why I said further in post #26: “... However, dirt particles can also impede the control plunger‘s movability … ... you might want to do an additional AFM/CP movability test as described in the following thread (post 22):
https://www.benzworld.org/forums/w12...o-knows-3.html“

But the OP decided (for whatever reason) to change the fuel pumps and the filter, instead.

BTW dugald, don‘t feel bad if you don‘t know what this "restrictor" is. Although it‘s one of the most important parts of the KE-Jetronic's FD, it is hardly known. … :wink_2:

H.D.

 

Okee, did the test earlier today.

I didn't feel anything weird the travel of the AFM from the first 2 mm play until the end feels homogeneous and continuous also at the beginning and end the end of the travel if doesn't feel if there is more or less resistance compared to the middle.

I have the the impression the CP can move freely all the way up and down and that the CP follows the AFM without hesitation.

Please tell me what I could do next.

 

... I didn't feel anything weird the travel of the AFM from the first 2 mm play until the end feels homogeneous and continuous also at the beginning and end the end of the travel if doesn't feel if there is more or less resistance compared to the middle.

I have the the impression the CP can move freely all the way up and down and that the CP follows the AFM without hesitation. ...

Actually that test consists of two parts. In the first part the (~ 2 mm) play and the resistance of AFM & CP on the plate‘s slow travel down and the AFM's freely jumping back to its base position is checked. In the second part the CP‘s following the AFM on its slow travel back to its base position is checked. And prior to each pushing down of the AFM plate the fuel pumps are primed by turning the key at least once to ignition on in order to ensure full holding pressure. … Based on what you say, the AFM/CP movability seems to be okay, though.

... Please tell me what I could do next.

Since this problem started after the FD filter fitting replacement, the first suspicion that comes to mind is that dirt got into the FD during that procedure. Another suspicion that comes to mind is that you may have created a false air leak during that procedure, for instance, by accidentally pulling off a vacuum line.

I suggest to first make sure there‘s no vacuum leak. The next thing I‘d suggest is a fuel volume flow test at the (axial) outlet port of the fuel pressure regulator.

BTW, I like to see engine bays as clean as yours. … :thumbsup:

 

On the old filteryou removed did you see any filter inside it ????? Some models dont have this filter fitted . And did you try the old one back in place ?..

 

I believe these questions were answered earlier in the saga: yes and yes.