1984 w201 190E fuel pressure spec.

[Krleenm]

Hi newbie here looking to find out what the spec. Fuel pressure is for a 84 190E 2.3l I am showing 5.0 bar. I have found no specs. Online for this year. I am troubleshooting a KE jetronic issue, fuel pump intermittently shuts down. The fuel pump runs in start mode only. This seems to happen most in deceleration it will just quit. Any thoughts would be greatly appreciated.

[Dmitry at Pelican Parts]

Welcome to the forum! You'll find a ton of info here from our members and moderators. Check out the link to one of our tech articles for your 190; I think it'll help you troubleshoot and hopefully resolve your fuel pump issue. If you need further technical info, feel free to post a Comment just below the article and someone will get back to you with more detailed info. Best of luck and let us know how it goes!

Mercedes-Benz 190E Fuel Pump Replacement | W201 1987-1993 | Pelican Parts DIY Maintenance Article


-Dmitry

[Stretch]

Originally Posted by Krleenm

Hi newbie here looking to find out what the spec. Fuel pressure is for a 84 190E 2.3l I am showing 5.0 bar. I have found no specs. Online for this year. I am troubleshooting a KE jetronic issue, fuel pump intermittently shuts down. The fuel pump runs in start mode only. This seems to happen most in deceleration it will just quit. Any thoughts would be greatly appreciated.

The specifications are all listed in the FSM on www.startekinfo.com

You will hear the fuel pump running when you switch the ignition to the second but last position - it is then meant to stop until the ECU gets a signal from the crank sensor. This will happen when the start motor spins and when the engine is running.

The engine will not run with out fuel pressure from the electric pump.

If you are getting intermittent stalling (the engine runs most of the time) then it probably won't be the fuel pump.

"Deceleration stalling" is more likely to be due to the road speed sensor (if fitted) or the signal between the automatic transmission (if fitted) - if you have a manual gearbox then you need to post back for some other tips!

[Krleenm]

Hi, just checked www.startekinfo.com but they state Coverage includes information starting with Model Year 1994, 10 yrs newer than mine. This car does have an automatic
trans. I suspect my fuel pressure is on the low side since most specs I have seen stated is a min. of 5.3bar (that's for other yr makes though). I have been leaning towards a faulty fuel pressure regulator. This car sat for quite a few years so I have removed and cleaned out the fuel tank and replaced the fuel pump. I have also removed the fuel injectors and cleaned them and installed new packing.

[Frank Reiner]

Originally Posted by Krleenm

Hi newbie here looking to find out what the spec. Fuel pressure is for a 84 190E 2.3l I am showing 5.0 bar. I have found no specs. Online for this year. I am troubleshooting a KE jetronic issue, fuel pump intermittently shuts down. The fuel pump runs in start mode only. This seems to happen most in deceleration it will just quit. Any thoughts would be greatly appreciated.

When the pump shuts down during deceleration, how do you determine the point of shut down? Does deceleration mean a 60-t0-40 MPH slow down, and then an attempt to return to 60 MPH, or does deceleration mean rolling to a stop? If the pump subsequently runs only while cranking the engine, how long is required to return to "normal" operation?

5.0 bar operating pressure is not unusually low for a single pump system.
The switch to two pumps brought an increase to ~ 6.3 bar.

[Stretch]

Originally Posted by Krleenm

Hi, just checked www.startekinfo.com but they state Coverage includes information starting with Model Year 1994, 10 yrs newer than mine. This car does have an automatic
trans. I suspect my fuel pressure is on the low side since most specs I have seen stated is a min. of 5.3bar (that's for other yr makes though). I have been leaning towards a faulty fuel pressure regulator. This car sat for quite a few years so I have removed and cleaned out the fuel tank and replaced the fuel pump. I have also removed the fuel injectors and cleaned them and installed new packing.

Go back to startek

Click on MB Workshop resources (left hand side)

Click on CD/DVD

Choose flavour - 'tis free and easy to access (especially for the W201 as it runs no flash player interface that often cocks things up)


##################

Does the speedometer work?

Check for the presence of a road speed sensor by looking for the wiring on the ECU plug (easier to reach than the sensor on the back of the speedometer) and compare with the ECU plug wiring positions in the FSM (see above)

[Krleenm]

OK where to start? Lol lets start with Frank, the system shuts down as soon as I come to a stop. The time it takes to start again is typically around 1 to 2 minutes (which everyone behind me appreciates at an intersection) I usually have better success if I work the throttle a bit. OK for Stretch, I will check out starteinfo.com again. The speedometer works fine, no glitches nice and smooth. I did get some good Info from Nick on this site, he gave me this;

Sounds low. You may have a weak pump or regulator issue.

Specs for your system:


System Pressures:
Cold or Warm 5.3 - 5.5 bar (77 - 80 psi.)
Residual Pressure, after 30 Min. 2.8 bar (40.5 psi.)
Lower Chamber Pressures:
Presure specifications given are in bar (psi) below previously measured system pressure.
Normal Operating Temp. 0.4 bar (5.8 psi.)
Idling 68°F (20°C) 0.4 bar (7.3 psi.)
Enrichment Pressures:
Measured at lower chamber port.
Acceleration Enrichment 20°C (68°F) min. 3.8 bar (55 psi.)
Full Load Enrichment (Normal Temp) approx. 0.4 bar (7.3 psi.)
Below measured acceleration enrichment pressure.
Deceleration Pressure:
Measured at lower chamber port.
Decel Pressure Must equal system pressure - Nick at Pelican Parts

Thanks All!

[Frank Reiner]

Originally Posted by Krleenm

OK where to start? Lol lets start with Frank, the system shuts down as soon as I come to a stop.

Possibility I -
As the car coasts down, the KE ECU commands the Electro-Hydraulic Actuator (EHA) in the Fuel Distributor (FD) to move to a fuel shut-off condition. If the ECU does not recognize that the engine speed has dropped below ~1200 RPM the fuel flow will not be restored. The fault may be internal in the ECU (temperature?). The fault may be mechanical, and related to deceleration G-forces slightly shifting the position of wires, or changing the continuity of contacts in wire connectors.

Possibility II -
Also related to decel G-forces, the wiring and/or connectors for the fuel pump relay may be losing continuity, or the fuel pump relay itself may have a cracked solder joint inside.

The time it takes to start again is typically around 1 to 2 minutes (which everyone behind me appreciates at an intersection) I usually have better success if I work the throttle a bit. OK for Stretch, I will check out starteinfo.com again. The speedometer works fine, no glitches nice and smooth. I did get some good Info from Nick on this site, he gave me this;

Small changes in temperature during the 1-2 min. interval may be enough to restore continuity.

[Stretch]

I hate to be a pain in the arse but the stalling - stuttering at traffic lights is typical road speed sensor trouble.

I don't know for sure when this was added to the KE system but it was certainly about from 1988 onwards.

[Frank Reiner]

Originally Posted by Stretch

I hate to be a pain in the arse but the stalling - stuttering at traffic lights is typical road speed sensor trouble.

I don't know for sure when this was added to the KE system but it was certainly about from 1988 onwards.

This might seem to be confirmation of the maxim that:
"The squeaky arse gets the grease."

Stretchman, would you walk us through your understanding of the mechanism of engine stalling and failing to restart for 1-2 minutes as a function of some fault with a vehicle speed sensor (VSS)?

[Krleenm]

Hi guys, some good info for sure! The wiring scenario is a definite possibility in as much as the loom on this engine is most definitely cooked, (I would love to replace it) I have repaired/replaced a fair number of wires on this. I wish MB had a connector kit for these so I could build a new loom. I have found nothing online but one could hope some day☺️. Frank I think your possibility #1 is a good possibility. I have opened the fuel pump relay and the boards look to be in good shape, though without any method to test it I cannot be certain. Stretch as far as I can tell I have no VSS I do have a crank position sensor I cannot recall where the fuel pump relay gets the signal for the auto trans. kickdown perhaps from the CPS. I did get into startekinfo.com really fantastic. I may finally figure out where a wire that was lying in the fenderwell belongs (its a brown with blue stripe wire with a single pin connector) none of the cheesy aftermarket manuals have been of any help. Thanks guys I will look harder at the wiring. I will wiggle the wires while it's running a little harder maybe I can get it to fail on demand.

[Frank Reiner]

Originally Posted by Krleenm

I cannot recall where the fuel pump relay gets the signal for the auto trans. kickdown perhaps from the CPS.

The FPR gets a "run" signal from the ignition controller (EZL). It also inhibits kickdown above a certain RPM to prevent overspeed.

A partial test of the FPR can be done by removing it and bridging circuits #30 and #87 (typically pins 7 & 8) in the socket. The pump will run continuously in this configuration, and the car can be driven to see if the symptom changes. Remember to remove the jumper when thru with the test!!

[Stretch]

Originally Posted by Frank Reiner

This might seem to be confirmation of the maxim that:
"The squeaky arse gets the grease."

Stretchman, would you walk us through your understanding of the mechanism of engine stalling and failing to restart for 1-2 minutes as a function of some fault with a vehicle speed sensor (VSS)?

I can "walk you through" my understanding - but this is only applicable to the systems with the road speed sensor.

From what I can make out there are only two ways in which the CIS gets adjusted by the ECU: (1) The electro hydraulic actuator (EHA) and the air idle control valve. Everything else that goes to the ECU pin is a measurement to help adjust these two transducers.

The road speed sensor seems to get used to interface a setting between the EHA and the air idle control valve. Essentially if the road speed sensor is saying "we're still moving" the ECU doesn't activate the air idle control valve in time and the engine stalls.

Because the setting of the air idle control valve (and probably the EHA) is all cocked up (technical term - I don't want to dazzle you with science here!) the ECU is stopping the engine from starting again because the fuel mixture is all cocked up. Stamping down hard on the accelerator in panic and turning the ignition key might help an engine to chug a bit but until the ECU "realises" that the car isn't moving things might remain a bit frustrating...

...for some strange reason that I haven't gotten to the bottom of yet - the signal from the throttle position switch when closed seems to have less of an effect on the system than the road speed sensor...

[Krleenm]

Good stuff, I will manually run the fuel pump today and drive the car. I have a little harness I made up with a switch in line that I have used many times just for these situations.

[Krleenm]

Hi, I ran the car with the jumper in place on pins 7 & 8 it ran fine no cut out. I also changed out the fuel regulator with a known good one and didn't change anything engine still cutout. I put the FPR back in and the Engine wouldn't start, I left the cover off of it and found that one of the relays doesn't appear to be working right I worked the contacts a bit on it and the engine started right up and runs as it should, no cutout. Looks like a faulty FPR what do you all think?

Thanks!