I've changed the filter, do u need to change the relay and fuel regulator before I try to take the fuel pump out. How can I besure the fuel pump is bad. 99 E150. 4.2 liter

 

Hi Bill,
the best thing to check is the fuel pressure at the fuel rail for the injectors. You can usually hear the fuel pump run for a few seconds when the ignition key is turned to run. Might have to listen at the filler cap while someone cycles the key. jim

 

Get a pressure gauge (might be able to rent on from oreillys) and attach it to the rail. It's pretty easy. Then you need to drive it under load while watching the gauge (we use a dyno at our shop, but you can just run the hose under the wipers). That will help verify. Most shops can do this and it shouldn't cost much. Better to have them verify than to waste time and money doing a pump.