Intermittent won't start

My daughters 2003 ford focus intermittently won’t start. It cranks fine but refuses to catch. I tried banging on the fuel pump relay and it started so I replaced it but the problem is back. I had my daughter jump on the rear bumper one time as the ford parts guy said it could be the fuel cutoff switch and it started. It never happens if the tank is more than 1/2 full or parked nose pointing downhill? weird? So could it be the cutoff switch?

2003 SVT ?
Any Check Engine Light Illumination ?

Shortly after a no start incidence, I’d take the car to a national chain Auto Parts store, like Advance Auto or Autozone. Most will have a counterman come out to your car in the parking lot and check for any DTCs (diagnostic trouble codes). If any codes or pending codes are found, write them down in their exact format (ex: PO123) and post them here.

Some 2002 & 2003 SVT Foci with various drivability problems, including no start, have needed to have the PCM (powertrain control Module) reprogrammed. Ford has developed a “revised” PCM calibration to improve problem conditions. Your car could be a candidate. Ford has the information used in checking this.

CSA

i’m not shure if that model year have a fuel cut out switch. the cut out switch is an inertia switch usally mounted in the trunk. it disables the fuel pump in a collision or a hard bump from either the front or back of the car. they must be reset manually. check the owners manual for location. it is usally mounted in the trunk, look for an acess port at the sides of the side panels, there should a reset button on top.
you mentioned that it never happens if the tank is more than half full or parked pointing downhill. this could possibly rule out fuel cut off switch.
i suggest having the fuel pump electric circuit checked. you might have a fuel pump going out.

My vote is for a fuel pump problem.

Where is the fuel pump located so I can check it for lose wires etc.? BTW thanks for the reply and advice

If you want to check the procedure & access for certain you should be able to get the info from Autozone’s website - register an email address plug in the car’s info & go to the Repair Info section.

But access to the fuel pump is probably under the rear seat. You just need to find the hidden release mechanism - check out along the front crease where the seat bottom meets the car body.