Autopapyrus · UAZ Patriot ZMZ-51432 Diesel (2014)
https://autopapyrus.com/guides/uaz/patriot/fuel-system-priming-and-fuel-delivery-check/
https://autopapyrus.com/guides/uaz/patriot/fuel-system-priming-and-fuel-delivery-check/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.
UAZ Patriot ZMZ-51432 Diesel (2014): Fuel System Priming and Fuel Delivery Check
The ZMZ-51432 has a Common Rail fuel system with an electric fuel pump in the tank and a manual priming pump on the filter housing. Priming is needed after a filter change, after running out of fuel, or after fuel line repairs. Do not loosen the high-pressure lines yourself: it is dangerous and not necessary for priming.
Parts
3| № | Part | Alternatives |
|---|---|---|
| 01 | diesel fine fuel filter with manual priming pump | Mann, Bosch, Knecht |
| 02 | Fuel line O-rings and sealing washersif replacing the lines | |
| 03 | Coarse fuel filter (water separator)if needed |
Tools
7- 10
- 13 and 17 mm wrenches (depending on the fuel line fittings)
- fuel catch container
- clean rags
- clear tubing of a suitable diameter
- fresh diesel fuel
- OBD scanner that can read rail pressure (for the check)
Step by step
12 steps- Shut off the engine, let it cool down, and disconnect the negative battery terminal. Fuel is drawn from the right-hand tank, so make sure there is fuel in it. Both tank caps must be closed tightly, otherwise fuel transfer between the tanks will not work properly.
- Prepare the work area: wipe down the filter housing and fittings. Dirt in a Common Rail system damages the injectors and the high-pressure pump.
- If you replaced the filter, fill the new filter with clean diesel fuel through the opening or the inlet fitting. Install the filter and tighten it without excessive force, following the marks on the housing or the filter manufacturer's instructions.
- Inspect the low-pressure lines, from the tank to the filter and from the filter to the high-pressure pump. Check the clamps and fittings for air leaks. A clear tube on the return line makes it easy to watch for bubbles.
- Reconnect the battery. Open the bleed screw on the filter, if equipped, and place a container under it.
- Pump with the manual pump on the filter until a clean stream of fuel without bubbles comes out of the screw. Close the screw and keep pumping until the pump feels firm.
- Turn the ignition on for 5-10 seconds so the electric fuel pump in the tank builds pressure. Turn it off, repeat 2-3 times, and prime again by hand.
- Crank with the starter for no longer than 10-15 seconds, then pause for about a minute. If the engine does not start after 2-3 attempts, repeat the priming. Do not crank for long periods: it can overheat the starter and drain the battery.
- After the engine starts, let it idle for 2-3 minutes. Check that there are no leaks at the filter and fittings, and that the idle is smooth.
- Check fuel delivery to the injectors: connect a scanner and watch the rail pressure at idle and while cranking. The pressure while cranking should rise quickly and hold steady. If it does not rise, or the rail fails to reach pressure, check the filter, look for air leaks, and check the electric fuel pump.
- Check the injector return flow (leak-off): with the engine running, the fuel should return without foam or air. A clear tube will show bubbles. Heavy return flow from one injector points to wear on that injector; have it evaluated at a repair shop with a test bench.
- If rail pressure does not build, the engine loses power, or you get pressure-related fault codes, fuel delivery may be restricted by a clogged filter, a clogged strainer in the tank, or a faulty pump. Check in this order: replace the filter, check the feed pressure from the in-tank pump, check the lines for leaks.
Common mistakes and warnings
- Pressure in the Common Rail reaches hundreds of bar
- Do not loosen the high-pressure lines or injector fittings with the engine running or right after it stops: a jet of fuel can penetrate the skin
- For the exact tightening torque of the high-pressure fittings and filter mounting hardware, follow the manufacturer's specification; values for the ZMZ-51432 are not clearly documented in open sources
- If you have no experience with Common Rail systems, leave diagnosis and injector removal to a repair shop