Change Fuel Distributor - big problem.

[seria]

Hi,
I posted exact thread at BenzWorld.org

1991 Mercedes SL500.
Fuel distributor and EHA leak. Change remanufactured Bosch fuel distributor and new EHA. No more fuel leak. At the same time change all air distribution hoses to fuel injector including seals. Start the engine, idle fine for a minute or so and engine start to run really rough. step on accelerator engine die. Again start the engine, engine starts immediately and run rough. Again step on accelerator, engine die.
Change Fuel distributor and EHA back to old unit (leaking units). Start engine, engine starts immediately and run rough. Step on accelerator, engine die immediately.
Installed back remanufactured Bosch fuel distributor and new EHA.
Change both fuel pumps, fuel filter and Fuel Hose/Line (Fuel Filter to Fuel Line). No luck.
Check all fuses, no problem.
Distributor cap and rotor, practically new (only use about 1000km).

Now where do I start looking.
Appreciate all pointers.
Thanks.

[js1sj]

the diaphragm in the fuel pressure regulator may have broken leaking fuel through the vaccum hose into the engine intake, i would check here.

[seria]

Originally Posted by js1sj

the diaphragm in the fuel pressure regulator may have broken leaking fuel through the vaccum hose into the engine intake, i would check here.

Hi,
How do I check the diaphragm in the fuel pressure regulator?
Thank you.

[seria]

Originally Posted by js1sj

the diaphragm in the fuel pressure regulator may have broken leaking fuel through the vaccum hose into the engine intake, i would check here.

Thanks. Parts on order are:
1. Fuel pressure regulator 0438 161 013
2. Fuel accumulator 000 476 1021
3. EGR valve 119 140 0260
4. Brass Fuel Fitting - For fuel going into the fuel distributor with screen.

Please keep suggestion coming.
Thank you.

[ctaylor738]

Can you check the current going to the EHA? It is measured in mill-amps, and there is a special harness that allows you to connect a meter.

It sounds to me like the EHA is not getting the right signal from the computer to provide fuel when you hit the gas. I believe that there is a potentiometer that indicates throttle position. If this signal isn't right, the computer won't know to provide enrichment and you will get stalling like you describe.

[seria]

Originally Posted by ctaylor738

Can you check the current going to the EHA? It is measured in mill-amps, and there is a special harness that allows you to connect a meter.

It sounds to me like the EHA is not getting the right signal from the computer to provide fuel when you hit the gas. I believe that there is a potentiometer that indicates throttle position. If this signal isn't right, the computer won't know to provide enrichment and you will get stalling like you describe.

OK will search the forum on how to check EHA.
Thank you for your valuable input.
Regards.

[partsman225]

may a ask what brand F/Dist you went with ?

[seria]

Originally Posted by partsman225

may a ask what brand F/Dist you went with ?

It's a BOSCH fuel remanufacture fuel distributor from Vertex auto. It's exactly the same as my old unit. The box says "Python Injection". Presume this remanufacture comes from "Python Injection". The FD part number is 0 438 101 016.

[partsman225]

Originally Posted by seria

It's a BOSCH fuel remanufacture fuel distributor from Vertex auto. It's exactly the same as my old unit. The box says "Python Injection". Presume this remanufacture comes from "Python Injection". The FD part number is 0 438 101 016.

man Python sucks . my F/D MAN said he took some new one down and found sand in them. my guy is larry at www.cisflowtech.com call him. tell him Gary in b.r. la. sent you ,he can give you good intel on F/D's

[seria]

Originally Posted by partsman225

man Python sucks . my F/D MAN said he took some new one down and found sand in them. my guy is larry at www.cisflowtech.com call him. tell him Gary in b.r. la. sent you ,he can give you good intel on F/D's

Wow... This is serious man. If sand were found in F/D then most probably the injector is blocked. How do I check that?
Thanks for the info man.
Regards.

[partsman225]

Originally Posted by seria

Wow... This is serious man. If sand were found in F/D then most probably the injector is blocked. How do I check that?
Thanks for the info man.
Regards.

you can't check it , if you take it part , it will void warranty. call larry he is the man! F/D'S I personaly saw pretty messed up things one some brands. larry does flow check all his F/D's on a machine.

[seria]

Thank you all. I shall go through each one of them. Currently have problem obtaining fuel pressure tester. Have asked a number of seller and they do not ship internationally.
Regards.

[tgolden]

http://www.humanspeakers.com/audi/tuning-cise.htm

Another useful link to help troubleshoot a Bosch CIS-E system.

Regards

[tgolden]

http://z3.invisionfree.com/Mercedes_190E/index.php?showtopic=13


Of all the Bosch systems,the KE Jetronic may be the most confusing to troubleshoot.The system combines electronics with mechanical fuel flow control.An analysis of driveability symptoms may point to either a mechanical or electrical problem,or not distinguish between the two.What follows is a logical sequence for analizing any driveability problem.

Verify Engine Condition

Run a compression test and/or cylinder leakage test.Check the valve adjustment and camshaft condition.Then verify the condition of the ignition system.If all of these test okay,then check the injection system.

Test Fuel Pressure

As in all fuel injection systems,any thorough system test must begin with fuel pressure.Connect a pressure gauge between the cold-start valve and the port on the lower chambers of the fuel distributor.Disconnect the electrical connector on the electrohydraulic actuator.Then activate the fuel pump.The pressure indictated should be between 75 and 82 psi.

If the pressure is too low,check the fuel pump volume.The pump should be able to deliver 0.5 gpm (gallons per minute) or more.If the volume is low,check the fuel filter and the line for kinks.If the pressure is low but the volume is acceptable,replace the system pressure regulator.

If the fuel pressure is high,disconnect the return line from the system pressure regulator and repeat the test.Ensure that the fuel from the regulator is captured in an approved container.If the fuel pressure remains high,replace the pressure regulator.If the pressure drops,clean or repair the return line.

The next step is to measure lower chamber differential pressure or the difference between the pressure in the lower chambers of the fuel distributor and system pressure.This measurement is done in two steps.The first step is to simulate pressure in the lower chambers with no correction based on engine temperature and exhaust oxygen.

Disconnect the electrical connector on the differential pressure regulator and close the valve on the pressure gauge.Activate the fuel pump;the differential pressure should be between 2.9 and 7.0 psi.If the pressure does not meet these specs,disconnect the return line from the lower chamber of the fuel distributor.A volume of approximately 5 ounces per minute should flow through the return line.If the pressure is wrong but the flow is correct,replace the differential pressure regulator.If the flow is incorrect,replace the fuel distributor.

If the first part of the test yields the correct pressure,then reconnect the differential pressure regulator with an ammeter in series and proceed with the second part of the test.The second step is to simulate the differential pressure of a cold engine.Disconnect the coolant temperature sensor and place a 15,000 ohm resistor across the terminals.Activate the fuel pump.Differential pressure should be between 10.0 and 17.5 psi.The ammeter should read between 50 and 80 milliamps.

If the pressure is wrong but the current is correct,replace the differential pressure regulator.

If both the ammeter and pressure readings are incorrect,check the resistance through the differential pressure regulator.If the resistance is greater than 21.5 ohms or less than 17.5 ohms,replace the differential pressure regulator.

If the resistance reading is correct,check the ECU power and grounds.Also check the ground for the temperature sensor.If these are OK,replace the ECU.

Test Rest Pressure

Rest or residual pressure is a measurement of the KE systems ability to retain pressure after the engine has been shut off.Open the valve on the pressure gauge and energize the fuel pump for about 30 seconds.Shut off the fuel pump and monitor the pressure for 10 minutes.The pressure should not drop below 38 psi.If the pressure drops too low,remove the differential pressure regulator and inspect the O-rings.If the O-rings are functioning properly or the pressure continues to drop when the test is repeated after replacement,pinch off the system pressure regulator return line.Repeat the test.If the pressure holds,replace the system pressure regulator.If the pressure still fails,replace the electrohydraulic actuator.

Test Injectors for Equal Flow

The injector equal flow test is an effort to determine how much contamination or restriction there is in the injectors.Remove the injectors from the intake manifold leaving them attached to the fuel lines.Place the nozzle of each injector in a graduated cylinder;energize the fuel pump.Push down on the airflow sensor plate.Flow the injectors for 30 seconds and let go of the plate.The volume should only vary 10% for all the injectors.

Replace any injectors that flowed 10% less than the rest of the injectors.

A helpful reference for troubleshooting:

Bosch Fuel Injection and Engine Management by Charles O. Probst

http://www.amazon.com/exec/obidos/tg/detail/-/0837603005/103-7517399-0753439?vi=glance#reader_0837603005

[tgolden]

After you get the engine running, you may need to adjust the exhaust CO level. The most cost effective tool I've found is the Gunson Gastester. See the link below.

Regards

http://www.englishparts.com/products/gb/Triumph/TR250-TR6/Gas-tester-digital-exhaust-CO-analyser-with-pulse-pump/1790146/SC-343265.html