Fuel Accumulator

I think that that picture is of a later TR accumulator (but maybe they are just using it as a generic accumulator picture).

Have you eliminated the fuel pump check valve and the seal inside the fuel distributor (that prevents the control pressure, and therefore, the supply pressure from bleeding off after shutoff IIRC)? Usually, if the accumulator is bad, the diaphragm is broken and fuel leaks out the drain fitting -- which is just open to atmosphere on a euro version so is obvious, but on a US version it has a return line to the tank (so if you remove that line, and liquid fuel comes out = bad accumulator).

 

Have to agree with you that that added "plug" is a strong clue that your accumulator does need replacing. No downside to running a line from that drain fitting back into the (upper part) of the fuel tank like on the US version (you want the added line to go into the top of the tank so, if it fails for some reason, fuel won't drain out of the tank via that line) -- but you might need to add a "T" into an existing line as I don't think that there are any unused extra fittings available.

I believe that your F PN 113978 accumulator is Bosch 0438170004 (the Bosch PN should be stamped into your old accumulator body somewhere to confirm/deny):
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Hi Gents, my unit is open to atmosphere, are you saying that if it fails fuel comes pouring out engine running or not? Cheers, Bell

 

So if this rails fuel comes out? Sounds to me that a pipe clear fuel pipe should be returned to the petrol tank, that way if it does fail you can see it. I am quite frankly staggered that this obviously lethal point of failure could be left on any car. Are you guys sure about this? Kind regards, Bell

 

Absolutely certain -- your hemisphere was slower than the US to mandate safety issues

 

I've been working on the fuel system of my Euro Mondial 3.2 and can confirm that the fuel accumulator has an outlet pipe open to the atmosphere as indicated on the parts diagrams. As Bell says this appears to be a fire hazard if the accumulator fails and fuel is emitted.
I found that the end junctions of my flexible stainless hoses from the fuel pump to accumulator and accumulator to fuel filter were badly corroded and both hoses needed replacement. The pump to accumulator hose (123022) is still available from ferrari classic parts but I understand the longer accumulator to filter hose (117952) is no longer available and I had to have one specially made up.

 

I'm just pulling this out of the air. I believe the accumulator has a diaphram in it. For proper movement of that diaphram it may need to be open to the atmosphere to allow free movement as designed. If attached to the tank then tank pressure on a hot day may affect drivability, possibly based on accumulator not being able to function as designed. Fuel should never pour out of there unless there is a failure. A failure is unlikely to be catastrophic in nature and if there is a failure one should smell fuel and know to do something with their vehicle. The person who put the hose on there and closed it off is a hack and didn't know what they were doing and should not be working on any car.

OK, now I need to pull out my injection book and see the inner operation of that piece.

And remember, there are other things that can leak back there like the fuel lines. The fuel lines are not double wrapped for safety and they will pump fuel all over the engine if there is a failure. There are scarier things back there than the accumulator. I say replace it and forget about it.

 

PV Dirk Quote:
I'm just pulling this out of the air. I believe the accumulator has a diaphram in it. For proper movement of that diaphram it may need to be open to the atmosphere to allow free movement as designed. If attached to the tank then tank pressure on a hot day may affect drivability, possibly based on accumulator not being able to function as designed. Fuel should never pour out of there unless there is a failure. A failure is unlikely to be catastrophic in nature and if there is a failure one should smell fuel and know to do something with their vehicle. The person who put the hose on there and closed it off is a hack and didn't know what they were doing and should not be working on any car.

Mmm I second this, that's just what I was thiking last night.
I'm gonna vent mine to a safe area of the car but not to the tank.
I'm currently trying to find an exploded view of one to see how it works

 

Ah great, thanks for the diagram, it's just as I thought it would be. So the diaphragm gets a hole in it and you are a dad...I mean you have a fire... ;-)

 

Gentlemen, great post. I will change the accumulator in my Mondial 3.2 ASAP. Can't believe it's lasted since August 1988!
Great info; THANKS!!!

 

When I disconnect the lines in and out of my Mondial's accumulator, will high pressure fuel spray out? If so, approx. how much?
Thanks!

 

Remove your fuel pump fuse, start the engine until it stop by itself and the accumulator should be empty.

 

Not much quantity. It is under pressure. IIRC, I put my wrenches in place and then put a rag or paper towel around them and opened it. Good form to always wear safety glasses when working on a car.

Other suggestion is to make sure all these joints are clean before you open them. Don't need any grit in the system. It may be before the filter but always good precaution, also with replacing the filter, don't need any bits of grit getting directly into the injection machinery.

And be careful, joints are tight, not overly so but my hand slipped hitting something causing me to leak a bit out of my hand.

 

Actually this is a funny but nice discussion. My personal experience with the k- Jetronic ( ovef 30 years)is that hot start issues are rare caused by the fuel accumulator. MvT story seems to confirm: his accumulator is way beyond an initial issue but he only recently had a hot start issue.

In my experience hot start issues are in most cases caused by leaking injectors. To MtV. Please report back on your results if possible.

 

Thanks!