Change Fuel Distributor - big problem. - PeachParts Mercedes-Benz Forum

seria · #1 03-01-2011, 07:55 AM

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 · #2 03-01-2011, 02:42 PM

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 · #3 03-02-2011, 04:24 AM

Quote:

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.

partsman225 · #4 03-02-2011, 10:26 AM

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

seria · #5 03-03-2011, 07:36 AM

Quote:

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.

seria · #6 03-03-2011, 07:39 AM

Quote:

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 · #7 03-04-2011, 09:59 AM

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 · #8 03-04-2011, 10:05 AM

Quote:

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 · #9 03-04-2011, 11:08 AM

Quote:

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 · #10 03-05-2011, 07:43 AM

Quote:

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 · #11 03-08-2011, 10:16 AM

Quote:

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.

tgolden · #12 03-08-2011, 05:59 PM

If you think the injectors might be obstructed, you should pull them individually and check the flow and spray pattern. It's also a good way to see if the FD is functioning properly. If the mechanical injectors exhibit problems, you should replace them.

To check the flow pattern, pull a single injector and observe the shape of the spray cone while cranking the engine. It should be uniform and be similar to the other injectors. You can measure the flow by measuring the volume of flow per a unit of time. A graduated cylinder works well for this test.

Regards

http://www.witchhunter.com/injectorfaq1.php4#what2

CIS, injectors, these are a mechanical injector. They don't clean well due to design, and the internal filters are not replaceable. Best to replace any suspect injectors as most are in poor shape due to internal rust.

See also:

http://www.mbca.org/forum/cleaning-mechanical-cis-fuel-injection-nozzles-and-other-impossible-things

tgolden · #13 03-08-2011, 08:18 PM

Change Fuel Distributor - big problem.-cistroubleshooting.jpg

This may help as a troubleshooting guide.

Regards

JohnM. · #14 03-08-2011, 08:42 PM

Quote:

Originally Posted by tgolden

Attachment 90252

This may help as a troubleshooting guide.

Regards

Thanks for that. I've never seen it posted anywhere before. Cool chart!

tgolden · #15 03-08-2011, 11:35 PM

http://www.cabby-info.com/Fuel_System.htm

The above link has a lot of Bosch K-Jetronic CIS technical information that should be sufficent to solve any issue with the Bosch K-Jetronic fuel injection system. Just take your time and diagnose the problem and do the correct tests. To fully test and tune a K-Jetronic system you will need access to a K-jet pressure tester and exhaust gas analyzer to measure CO.

Regards