Possible malfunctions of the pump can be: a violation of the tightness of the diaphragm and valves, a decrease in elasticity or breakage of the diaphragm spring, wear of the pump drive parts

To disassemble the pump, remove the head cover 10 (see Fig. 1), gasket 9 and filter 8 from it.

Then unscrew the screws securing the head 14 of the body, separate the head from the diaphragm.

Fuel pump B9V (451M–1106010–30, 451M–1106010–30)

Fig. 1. Fuel pump B9V (451M–1106010–30, 451M–1106010–30)

When removing the housing head, be careful not to damage the diaphragm, as the diaphragm sticks to the head and housing flanges.

Next, disassemble the drive mechanism, for which first press out the axis 19 of the drive levers and remove the lever 17 and spring 16.

Fuel pump 2105-1106010-50

Fig.2. Fuel pump 2105-1106010-50

Carefully release diaphragm 6 and remove it and spring 5 and seal 3 with washer 4.

When disassembling the head, remove the inlet 7 and discharge valves. To do this, press out the valve clips.

After disassembly, wash all parts in kerosene or unleaded gasoline, blow with compressed air, dry and inspect them.

Fuel pump diaphragm assembly tool

Fig. 3. Device for assembling the diaphragm of the fuel pump: 1 - body; 2 - locating pin; 3 - pump diaphragm; 4 - key; 5 - handle; 6 - handle axis

The diaphragm must be airtight, its varnish coating must not have peeling. If it is necessary to replace the diaphragm blades, assemble it on a special device (Fig. 3).

The diaphragm spring should have a height of 50 + 5 mm in a free state, and 15 mm under load (5 ± 0.2) kgf.

Check the elasticity of the pump spring on the model 357 GARO. Valves must be free of warpage, cracks, dents and visible signs of wear.

The valve springs should press the valves against the seats tightly, without gaps. The pump drive levers and their axis should not have much wear.

The maximum clearance between the axis of the levers and its bushing, as well as between the bushing and the levers, must be no more than 0.25 mm.

Fuel pump drive lever

Fig. 4. Fuel pump drive lever

Particular attention should be paid to the wear of the working surfaces of the lever (Fig. 4) at the points of their contact.

Before assembly, check the fit of the flanges of the pump head and the pump body. The deviation from the plane should be no more than 0.08 mm. Lapping if necessary.

To disassemble the Universal pump (see Fig. 2), unscrew the screws securing the cover 14, remove the cover and filter element 8, unscrew the screws securing the housing 13 to the bottom cover, separate them, remove the diaphragm assembly and spring 7.

Rinse all parts with gasoline and blow with compressed air.

Check the integrity of the springs.

Check for valve sticking.

Check apertures. They should not be cracked or hardened.

After checking, replace any worn or damaged parts with new ones.

Always replace pump gaskets with new ones and lubricate with a thin layer of grease before installation.

Assemble the pump in the reverse order of disassembly.

Position of the fuel pump head when installed

Fig. 5. The position of the fuel pump head when it is installed

When installing the B9V-B pump head, its position relative to the housing must correspond to fig. 5.

Tighten the head mounting screws with the diaphragm pulled to the lowest position using the manual pumping lever.

This assembly provides the necessary sag to the diaphragm and relieves it from excessive tensile forces that lead to a sharp reduction in the durability of the diaphragm.

After assembly, check the pump on the device models 527B or 577B GARO.

At a camshaft speed of 120 min–1 and a suction height of 400 mm, the pump must ensure the start of fuel supply no later than 22 s after switching on, create a pressure of 150–210 mm Hg. Art. and a vacuum of at least 350 mm Hg. st.

Pressure and the vacuum created by the pump must be maintained within the specified limits with the drive turned off for 10 s.

The pump flow rate at a camshaft speed of 1800 min–1 must be at least 120 l / h.