The last post was from 2009. The OP and another poster have not been active since. I suggest you start your own thread with your question? What problem(s) are you having that leads you to believe that you need both relays.

 

1992 Ford E350 cutaway RV with 7.5 Liter 460 CID cubic Inch displacement. and about 74,000 miles. Background: At 70 MPH interstate the engine just stopped as if the fuel system turned off. Made a safe exit with tow 25 mile back to lavonia ga home base. Thinking fuel pump. The one in there was 5 years old. I dropped tank and installed new fuel pump. Forward to now: Engine will run momentarily and sounds good when starting fluid is sprayed in to the intake. After 5 second or so the engine stops again.
Question: how to access the fuse panel down below the brake master cylinder and coilde hard lines to inspect under the pane female slotted outs. Or how do I access these slots from above, and what solution will clean any corrosion in these sockets. I switched the relays around as I understand they are identical ( is this correct?)
My understanding of the start circuit: On engagement of the switch to on the fuel pump should pressurize the fuel rail and as switch engaages the starte the pump continues to run and allow the engine to start and continue to run. If the switch in on momentarily moved to start, the fuel pump circuit is turn off and on fuel continues to pressurize the rail.
So.... Spark does not seem to be the issue because the engine starts immediately on the starting fluid.
Your suggestions for further troble shooting are appreciated.
Buoyantly Professor Bob

 

This info saved me a lot of work! Thanks