Fuel pump or fuel injection unit?
 

I have an '89 300E which has starting problems. Sometimes OK, other times it cranks but won't fire up. Usually OK after sitting for a day. It shows symptoms of not getting fuel. Is there a simple way to check for defective fuel pump or bad fuel injectoion?

fuel issues
 

To check whether the fuel pump, per se, is defective, pull the line coming out of the fuel pump at a convenient place and have someone crank it over. Though, you should change the fuel filter(s) before doing anything. If the fuel pump is okay then crack an injector line to see if the injection pump is working.

Fuel pumps
 

hello,

Remember your fuel pumps are electric.

If you run the car and get under while its running you can put your hand on each one and feel them. They wine and vibrate slightly.

However the fuel pressure is another story that needs to be handled under the hood where the Fuel Diaphraphm Pressure Regulator is.

brian