How to Clean a CIS K-Jet Fuel Distributor - PeachParts Mercedes-Benz Forum

Michael Stoic · #1 04-19-2003, 05:23 PM

1979 450SLC M117.985

Is it possible to flush the Fuel Distributor from sediments and contamination in the upper chambers?

My mechanic had detected contaminated fuel emerging from the FD injector lines (while diagnosing a no-start condition) and there had been other performance degradation prior to the car being parked for a few months.

In any event, fuel pressure tests rule out both the fuel pump and the control pressure regulator (warm-up regulator) and point to some likely fuel flow restriction in the FD and the Injectors.

I am wondering if the FD can be cleaned by emersion in a cleaner (like the Yamaha carb cleaner - designed NOT to react with rubber and plastic) or by another method?

Can the FD be power flushed on the bench? I know (I think) one method is to leave the FD on the car and flush it by energizing the FP and releasing the injector line fittings while keeping the air flow meter air sensor plate down, but would like to get input on which method is best/possible/recommended...

Many thanks for your input!

JRBrown · #2 04-20-2003, 12:27 PM

CIS fuel distributors are precision instruments and as such do not tolerate contamination well at all.

as an aside, I cut open a 70,000 OEM (Bosch) fuel filter on a volvo I just bought. There is a very long roll of filter media in there. I would be very surprised if the fuel filter would be the source on a BOSCH, Hengst, Mann or other european OEM supplier.

Contamination source will be the key to the direction you go.

1) if it's fuel varnish (not driving it for a very long time). Fuel system detergent might work, but a teardown is probably the only way to be sure.

2) if it's the distributor itself self destructing, then a new or known good used distributor is the only solution.

3) if it's upstream (either the filter self destructing or letting contamination through) then at a minumum a teardown is necessary to evaluate if the distributor is permanently harmed (scoring, rust, pitting...).

Some line flushing, new fuel filter and new fuel injectors will most likely be called for also. Please be careful. working with that much fuel exposed in a a confined space is bad news.

good luck.