The power and economic performance of the engine, as well as the reliability of its operation, largely depend on the thoroughness and quality of the adjustment of the parameters of the high-pressure fuel pump
Therefore, the adjustment must be carried out by qualified personnel and on special equipment designed for this purpose.
Injection pump is recommended to be adjusted on the stands "Star-12", "Minor-8", (VNR), NTs-108 and others similar in design.
The pump must be adjusted with a set of tested nozzles attached to the sections, the nozzles should be installed on the engine in the order they are attached to the pump sections.
When adjusting the fuel pump, first of all, the start of the fuel supply by the pump sections is regulated, and then the amount and uniformity of the fuel supply.
The start of fuel supply is controlled without an automatic injection advance clutch by the start of fuel movement in the momentoscope (Fig. 1).
The start of fuel supply in sections is determined by the angle of rotation of the pump camshaft when it is rotated clockwise, as viewed from the drive side.
The first section of a correctly adjusted pump begins to supply fuel 37-38˚ before the axis of symmetry of the cam profile.
To determine the axis of symmetry of the cam profile, it is necessary to fix on the dial the moment when the fuel begins to move in the momentoscope when the cam shaft is turned clockwise, turn the shaft clockwise by 90 ° and fix on the dial the moment the fuel begins to move in the momentoscope when the shaft is turned counterclockwise arrows.
The midpoint between the two beyond the fixed points defines the axis of symmetry of the cam profile.
If the angle at which the first section starts fuel supply is conditionally taken as 0˚, then the remaining sections should start fuel supply in the following order:
Section - degree of rotation of the camshaft
- #1 - 0˚
- No. 3 - 45˚
- No. 6 - 90˚
- No. 2 - 135˚
- No. 4 - 180˚
- No. 5 - 225˚
- No. 7 - 270˚
- No. 8 - 315˚
Inaccuracy of the interval between the start of fuel supply of any section of the pump relative to the first one is no more than 0˚20'.
The start of fuel supply is regulated by the pusher bolt 49 (see Fig. 2).
When the bolt is removed, the fuel starts to flow earlier, when screwed in later.
After adjusting, lock the adjusting bolt with nuts.
The amount and uniformity of fuel supply by the injection pump sections are regulated together with a set of injectors and high-pressure fuel lines 415 ± 3 mm long.
The volume of the internal cavity of each high pressure fuel line should be 1.3 ± 0.1 cm3, determined by the fuel filling method.
The sequence for checking and adjusting the magnitude and uniformity of the feed is as follows (the pump camshaft speeds are indicated):
- check the fuel pressure in the line at the inlet to the high pressure pump.
Pressure should be within 0.5-1.0 kgf/cm2 at 1050 min1.
If the pressure is too high or too low, unscrew the relief valve and turn its seat to adjust the opening pressure. After adjustment, caulk the valve seat;
- when the control lever rests against the bolt of the minimum speed, check and, if necessary, adjust within 275 - 325 min-1 the frequency of complete automatic shutdown of the feed by the regulator.
When turning out the bolt 1 (see Fig. 3) of the minimum speed and the body 41 of the buffer spring, the frequency decreases;
- with the control lever resting against the bolt for limiting the maximum speed, check the speed of the pump camshaft, corresponding to the start of the rack ejection (the start of the rack movement towards turning off the supply).
The regulator should start ejecting the rail at 1070+10 min-1.
If necessary, adjust the frequency with the maximum speed limiting bolt;
- with the control lever resting against the bolt for limiting the maximum speed, check the speed of the pump camshaft corresponding to the end of the rack ejection (complete shutdown of the supply).
The end of the rail ejection should be at 1120 - 1150 min-1 .
In case of deviation from this value, unseal and remove the cover of the inspection hatch of the regulator.
When removing the cover, make sure that the position of the adjusting screw remains unchanged.
The speed of the rack ejection end is adjusted as follows:
- changing the position screw 3 (see Fig. 3) of the two-arm lever, set the bolt for limiting the maximum speed, the start of the rack ejection at 1070+10 min 1 check the speed of the ejection end of the rack in, if necessary, adjust it.
When screwing in the screw of the two-arm lever and setting the start of the ejection of the rail at 1070+10 min 1, the speed of the end of the ejection of the rail decreases, while turning it out increases;
- when the control lever rests against the bolt for limiting the maximum speed and 1030± 10 min -1, check the performance of the pump sections.
The fuel supply by each section of the pump when working with injectors having an “H” sprayer and adjusted to the pressure of the beginning of the needle lift of 200+15 kgf/cm2, should be within 128—130 mm3 for each plunger stroke (cycle) for YaMZ-238PM engines and 138-140 mm per cycle for YaMZ-238FM engines.
The fuel supply by each section of the pump is regulated by the displacement of the rotary sleeve relative to the ring gear, for which it is necessary to loosen the clamping screw of the corresponding gear sector.
When turning the sleeve to the left relative to the crown, the feed decreases, to the right it increases.
After adjustment, check the tightness of the clamping screws;
- check the amount of starting fuel supply, which should be within 220 - 250 mm3 per cycle at 80 ± 10 min-1 .
Adjustment should be made with screw 31 (see Fig. 3) of the wings only in the direction of increasing the fuel supply, after which the screw should be locked with a chasing.
After adjustment, check and, if necessary, adjust the performance of the pump sections with the nominal flow adjustment screw;
- check that the fuel supply is turned off by the regulator bracket.
When the bracket is turned to the lower position by 45, the fuel supply to all sections of the pump should completely stop.
If the feed does not turn off, then you should check the ease of movement and eliminate possible jamming of the rack;
- - seal the high pressure fuel pump and regulator;
- - install the automatic clutch and tighten its fastening nut with a torque of 10-12 kgf-m.
The injection advance clutch nut is tightened in all cases when the high pressure fuel pump is removed from the engine.
