Accumulator (Component of K-Jetroinc CIS Fuel injection on 8v EV and 16v KR)

April 27, 2020, 07:41:33 PM

Thanks to eddypeck

THE FUEL ACCUMULATOR, also known as the FUEL DAMPER found in Bosch K-Jetronic[/url] systems, is located, inline, just after the fuel pump. So it's location is between the fuel pump and fuel filter. However due the the arrangement of the pump, accumulator and filter within on e compact unit it actually sits next to the fuel pump.

This is the fuel pump unit off the car, the accumulator is shown at the top, the pump is in the middle, inserted into the swirl pot and the filter is the bottom canister. This is the same set up for early K-jet 8v and all 16v engines.

The accumulator on it's own.

The unit is located in front of the rear beam on the right hand side of the car, in the void created by the rear bench. You can just see it here to the right of the middle box.

There are two part numbers shown and short and long accumulator fitted. I'm not aware of any technical difference, so either is suitable.

At time of writing they are still available new, but are generally an expensive part. Porsche, Audi, Saab, Volvo, Ford are among the manufactures that used the k-jet system. It's always worth looking for alternative parts and checking online sites worldwide. At present they are available as a Volvo part from American eBay for about half the price you can get them in the UK.

All K-JETRONIC systems must have this very important component fitted into the fuel supply line.

The housing of the fuel accumulator is split into two parts, the same as the fuel distributor. The difference is that the top part houses a very heavy compression spring, and as well, it has a safety fuel bleed outlet or, in other words, atmospheric discharge opening.

The joining point to the bottom half is a metal folding lip and houses a heavy duty diaphragm. The bottom part has internally a metal fuel deflection plate, where the inlet fuel line is connected to a metric fitting. The unit is not serviceable and although described above as in two parts, it cannot be split.

The exact location of the fuel accumulator is as close as possible to the outlet of the fuel pressure pump, or main pump. This will inhibit any fuel pressure noises from the fuel pump. The relationship between fuel flow and fuel pressure, are constantly changing. The fuel accumulator will now assist in keeping the pressure and flow in the fuel distributor bottom half always the same.

The fuel accumulator now has the ability to take into itself the reserve pressure and flow from the fuel pump. Due to the long fuel line to the engine bay, known as fuel pipe flow friction and the system pressure regulator valve in the fuel distributor head, this keeps the diaphragm of the fuel accumulator compressed and therefore stores more fuel while the pump is running.

By acceleration, some of the fuel FLOW AND PRESSURE will enter the top half of the fuel distributor, which can only go ONE WAY to be discharged by the injectors. The diaphragm in the fuel accumulator can now compensate for the fuel diversion to the injectors, or fuel diversion via the system pressure relief valve. The fuel accumulator also plays the role of controlling the fuel flow ' back up '. Either to the injectors or via the system pressure valve.

In short:
The purpose of the fuel accumulator, is to maintain pressure in the fuel system to prevent fuel vaporization while the vehicle is not in
use. The system has several check valves inside that close, sealing off the fuel return lines to the tank. When the accumulator fails, or is beginning to fail, you will notice problems starting when the engine is hot.