Mk 1 VW Golf GTI Hints & Tips

Fuel delivery issues
Contaminated fuel due to rusty filler neck causing rust to drop in the tank and be passed through the fuel system, this can block injectors, fuel lines etc. You will need to replace the filler neck, clean out the tank, change the fuel filters and run some injection cleaner.
Fuel tank pick up pump either faulty or filter contaminated, this is located in the fuel tank and can easily be reached by removing the rear seat base where you will see and inspection hole giving you access to the tank. One of the tell tales of this being a problem is the car running for 5 - 10 mins and cutting out as the main fuel pump is not getting enough fuel.
Push pump faulty. This is fitted in a bracket with sound deadening foam underneath the right hand side of the car. It makes a clear buzzing noise so if you cant here it, it's likely faulty.
Fuel pump relay located with the rest of the relays part number is 321 906 059 C.

Remember to disconnect the battery when carrying out this work your dealing with both electrics and fuel here !

Water Temp Sender Issues
First thing to check is your thermostat if it is stuck open your car will take an age to warm up propably, the easiest way to tell is feel your top radiator hose on startup if it is warm straight away then it is stuck open it should remain cold until water reaches tempreture then open the thermostat. Now if the thermostat fails to open you are likely to overheat. Over things to check if your tempreture gauge is reading hot are check the electric fan is cutting in, (you will have to leave it running a while) if it's not check the electrics and if needs be change the radiator sensor. There is also a sensor on the water pump you could try replacing in case it is giving you a false reading, the actual instrument gauge could be faulty and one other thing you could try is changing the radiator overspill tank cap from the black one to the blue one it release the pressure quicker.

Wet Floor
Even though the water is in the back it is usually coming from the front and running into the back, first check under the bonnet make sure the drain holes either side of the scuttle panel are clear and clean any rubbish out of the heater matrix cover. Check the window screen seal for leaks, check the radio aereal cable grommet is not missing or damaged and check the bottom of your doors to make sure there is no water leaking through the bottom of the door panels (missing plastic liners).