Bosch Fuel Injector Issue

Looks Like the brownish tank crude that was removed from my tanks. Old.gazoline residues that are dislodged by modern fuel. Looks like brown flakes.

Maybe you should remove the intank mesh filters as well as the "plug" that sits on the bottom of the middle tank, and thoroughly flush the tanks (water will flow/exit from the removed mesh filter and plug), then new thin screens from a jeep (thinner than our mesh screens) to get rid of the last bits of crude "flakes".

The issue is that small debris do pass through the pumps that grind them down to a "thinned camo paint" substance. It did happen to my son's BMW... Had to replace pump and filter twice. This was cheaper than removing the tanks. On the Ferrari tanks removed, but what a pain!

 

This is something similar to what you describe. In my case these deposits were clogging up the WUR filters. The pic shows the filters (the circular disks) and in the centre, a little pile of green deposits very like a fine sand in texture. I'm fairly certain it is a deposit resulting from the addition of alcohol to the fuel, which reacted with moisture in the fuel. We have had E5 and more recently E10 (10% alcohol content) fuel in Ireland for some years. On other cars I have had similar problems, with brownish coloured deposits. Sometimes the deposits formed a powder (where the fuel was exposed directly to air- eg in carburettors or mechanical fuel pump filters), but wherever the deposits were below the liquid level, the result was a sticky brown deposit which was extremely difficult to remove.
I can't understand how anyone could "clean" out the fuel tanks without removing them, based on my own experience. With (in effect) three tanks to flush through- not to mention the two crappy suction filters at the exit from the fuel "sump" (don't know the proper name for this).

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Like Raemin says, I also did a full clean through the entire fuel system and replaced some injectors which were dribbling. I could not tell whether any of the deposits shown above got through to the injectors, or if these deposits were responsible for the less-than-perfect spray pattern. I have a mixture of brass and steel injectors, and have not observed any difference between them as far as contamination is concerned.
Not sure if this helps, just my 2c worth!

 

But having said all that, if the filters at the exit from the fuel sump were replaced and in perfect condition, and if the in-line pressure filters also renewed, the deposits you describe must be originating somewhere between the filters and injectors. I would be inclined to renew the filters again, just to limit the extent of the investigation required.

And a further question- are the injectors on both banks clogging/failing?

 

There are filters "before the pump", built.in the fuel pickups. Usually they need replacing.

You need some highflow filter, or you may starve the pumps.

https://www.ferrarichat.com/forum/threads/v-12-maintenance.307168/page-4#post-147684600

 

Wouldn't that suggest that the problem is in the fuel, and/or the fuel tanks?

 

Seems strange, the cheap ones I bought from ebay were all perfect. It's quite easy to test: pull the injectors out of the plenum, put them in clear plastic bottles, actuate the fuel distributor disc, and look at the spray pattern.

On top of it, if there is crude in the injector, it is rapidly cleared once the injector is open. Worst case, the injector does not shut down properly and drips, but not likely to be clogged by something that managed to pass through the extremely thin window of the k-jet distributor plunger.

Is he trying to back-flush the injectors? This does not work with k-jets.

 

Make sure he uses the correct fuel flow and pressure, otherwise, it will give you a wrong (misleading) test result!

 

Just illustrating my previous post: if the crude can pass through this very narrow window ( the small line, not the big round), it has no problem flowing through the injector apperture that is probably 10 time larger.

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You should ask a k-jet specialist, but from my personnal experience, these injectors are quite simple, and there is hardly anyway they can go wrong when new.

With extensive wear, they may deliver an uneven spray pattern, or even leak a few drop of gazoline when they should not, but this would result in so-so mixture, not a complete failiure.

You can have a look at this tester to understand how these injectors do work and how to properly test them: https://mercedessource.com/store/bosch-mechanical-fuel-injector-mfi-tester-and-cleaning-kit



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This part sits in the middle of the distributor, gazoline comes in through the round holes and is then distributed to the injectors through the 6 thin windows. The plunger moves within the part and more or less obstruct the windows which adjusts the flow.

Part in the distributor:
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Plunger inserted
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Let's hopes this makes it clear.

 

There is a LONG LONG way from the tank to the injector - if I am not mistaken, it has to pass through 7 filters...

 

Earlier j-jet jad more filters than the later ones, but indeed quite a few filters can be clogged before the injectors.

I would disconnect the input hose from the distributor (not the return hose), let the pumps work, collect the gazoline in a bucket and see how it looks. At least this would let us know if the problem is before or after the distributor. If it is after it's a matter of sending the k-jet parts to a specialist. If it is before, time to drop the tanks.

 

The part with the narrow openings that raemin posted (and holds the Plunger) is typically called the "Barrel" in the Ferrari/Bosch (English) documentation, and the narrow openings are called the "Rectangular slots" or "Slits".

 

Looks quite comprehensive indeed...

Maybe he should try the bucket test on a hot engine: as the hot gazoline flows back to the tanks, it gets significantly warmer (it passes numerous times through the engine bay). Maybe that under these hot conditions, the crude gets dislodged?

For peace of mind you could buy once again new injectors: after all these are not expensive (I buy mine from eastern Europe on eBay).

Opening the filters could also be a good idea.

 

I have had this issue with many old Ferrari injected cars. The tanks have a rust colored residue that is very hard to get out. Sonic cleaning works best due to the baffling in the tanks. I use an external filter made by Earl's Performance. I order part # 230108ERL. It has a 35 micron sintered bronze cone filter. I machine the -8 fitting end to a 5/8 barb to fit the fuel pump feed hose. I install the filter just before the pump and leave enough hose to be pinched off with hose clamping pliers. This allows me to pinch off the fuel feed, remove the filter and clean it. They all have a rust colored paste that when dried becomes a super fine dust like material. It is a real pain and this is my best solution.

 

So you put this filter before the pump? No flow restriction?
Any photo would be greatly appreciated.

 

On German cars, the k-jets were installed with filters (one on the distributor inlet, and six on the injector outputs). These filters were removed after the first maintenance service as they were meant to trap the crude left during the assembly. Maybe this what the OP should use for a while?

As for the fuel filter, I use MAHLE EFG22 instead of BOSCH 0 450 905 021. These are slightly bigger, and do seem to filer very well. As they are very cheap I can replace them whenever I perform an oil change.