kyristen

I just bought a 1986 Audi 5000CS and have had nothing but problems. To make a long story short...my car has been in the shop three times now and it will run fine for a couple of days and then it won't crank. It turns, but there is no fire. The ignition coil, the thermal switch, and the cold starter switch has been replaced. It could be the fuel pump, or the starter control panel...at least this is what a friend has said. What I need to know is if the fuel pump is inside or outside of the tank. Or...if there is someone out there to whom this sounds familiar please help. The engine runs great when it is running. It is just so wierd. It runs and cranks for a couple of days and then it just quits! This has been very frustrating.

DaveN

Alas the problem is wide open, you need to determine if it is fuel or spark. Pull a wire when it is not working and arc it to the block, I just stick a screwdriver into the sparkplug cap. Don't hold it with your hands (high voltage can hurt) and have someone crank it. That way you can at least see if the problem is spark or fuel delivery.

Wrench

You do not make mention of the mileage on your car. After many or so miles the electrical connections will corrode, esp. if the rubber boots on them have deteriorated away. Try this: go into the engine compartment and disconnect and clean all the electrical connections on the engine, esp. the sensor ones. Coat them with some dielectric grease(available at electrical supply houses). See if that helps. Also check your ground strap for corrosion/erosion.
To answer your question, the fuel pump is inside the fuel tank. It will only run when it picks up engine rpm, as in when it is turning. It can be heard running after thr engine has been cranked. It makes a whirring noise.
A test to see if the fuel pump is inoperative is to jump the power connection to it. In the black box near the base of the windshield on the driver's side of the engine compartment you will find the fuel pump relay. Remove it and use a jumper wire to connect #30 slot to #87 slot. That should activate the pump. If not, then you need a new one. If it does, most likely it is the relay...
Wrench

TIREGUY

check the wires on the coil for corrosion