Polo classic 1.6 engine I replaced rear oil seal and sencer after all vehicle not spark, and injectors not spraying fuel.

very limited info generic answer did you do a relearn for the throttle body ---scan for trouble codes

What year is you Polo? If you are in any doubt about the fuel filter change it anyway! They are usually cheap to buy.
When was the vehicle last given a full service? Oil, Air and fuel filters can cause bigger problems that you would expect. Old spark plug can do the same.
I'll need a bit more information to help. When you drive it what exactly does it do? Is it low on power? Does it struggle when you accelerate hard? Does it stall at junctions? Does it idle unevenly? Use the comment button below and I'll try to help you more.
Fuel pumps generally last a long time and only fail on very high mileage engines. The only times they fail sooner is if it have not been used properly. Running a vehicle constantly with a nearly empty fuel tank causes the pump to overheat and wear out faster.
Most 4 cylinder engines use the firing order 1,3,4,2. Number 1 cylinder is the one nearest the belts and pulleys on the end of the engine.

1/4 inch above the seam on one side, down 1/4 inch on the other side with gasket sealer at the corners.

Your joking of course its all part of the flywheel and has a locating pin or offset fixing bolts ,so its fixed in position now have another look .

Sounds like the relay is stuck in an open position and needs to be replaced.

First of all you need to access the Engine Control Module (ECM) using suitable diagnostic equipment (VAS, VAG-COM or similar) connected to the data link connector of the car, in order to pull out all DTC's memored. DTC = Diagnostic Trouble Code. Then you will bu full informed about the root cause of the problem, and you will be able to repair & replace bad pieces and reset the ECM.

Remove engine to get to seal.

ENGINE MISSING CAN BE WEAK COIL.BAD PLUGS AND WIRES.REPLACE DISTRIBUTOR CAP AND ROTOR.FUEL FILTER STOPPED UP ALSO FUEL INJECTORS CLOGGED UP CAUSES MISSING.CHECK UNDERNEATH CAR WHILE IDLING.IF YOU LOSING A LOT OF OIL.FRONT CRANKSHAFT SEAL OR REAR MAIN SEAL LEAKING OIL.LEAKING VALVE COVERS.DO A COMPRESSION TEST.AND CHECK CONDITIONS OF SPARK PLUGS.IF PLUGS SOAKED IN OIL.VALVE GUIDES + SEAL LEAKING OIL IN COMBUSTION CHAMBER.

There should be no built up fuel or oil in cylinder. The fuel will be burned off immediately, and there should have been very little unless you have a leaking injector. The only way oil will enter the cylinder is if you have a mechanical failure like worn rings or leaking valve seals.If after replacing the plugs and wires did not correct all or the skip after the first start up and road test then you have another issue causing the skip

Hi! Saft question But as your B20/23 is a safe engine the Cam/timing belt hasn't sliped a few teeth. Also make sure all relays are well seated in the base including the Big round one behind the ash tray/stereo. Have you replaced the fuel relay with the correct one? they differ, one has Copper Tangs the other has plated?
Check the wires from the cam sensor at rear.
Hope this helps?
Paul 'W'
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