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Old 09-27-2003, 06:17 PM
RKreutzer RKreutzer is offline
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Join Date: Sep 2002
Location: Kingsport, TN
Posts: 375

First, if you turn the ignition key to the position just before start, you should hear a buzzing sound for about a second. That would be the fuel pumps at the passenger side inside of the rear wheel.
Sometimes it is easier to hear from the outside.
If you don't hear it, take out the fuel pump relay and clean the connectors/put some dielectric grease on it and try again. If still no go, you have to connect pin 30 (battery) to pin 87 (pumps) and listen to the fuel pumps. They should run now without stopping. If yes, Fuel Pump Relay is suspicious. If not running, pumps are suspicious, but it could also be a problem in the wiring. You would check that with connecting the terminals at the pump to the battery. Connect at fuel pump first, than battery. As a matter of fact, when working at the fuel pumps, the battery should be disconnected, as sparks might damage the relay.
Should pumps be running with direct connection to battery, then the wiring is somewhere interrupted.
Here is a picture of the fuel pumps (before replacement) on my 87 420. The power connections are under the rubber protectors. Do not overtighten, as these old pumps will start to leak out of the terminal.
Attached Thumbnails
Help with fuel problem 560SEL-cropped-fuel-pump-ass2.jpg  
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