1993 Ford E-350 Fuel issue

Idle air solenoid and/or intake vacuum leak.

It sounds like the pump is failing. That or sometimes not getting electricity. To check which it is, you could use a voltmeter or test light at the gas tank's electrical plug in. You need to check for power on the fuel pump wire when the engine is being cranked for starting. Do this when turning the key to on does not cause the pump to turn on for 2 seconds as it should. The fuel pump has power for those 2 seconds when key is turned to on, and again has power when the engine is cranked. You might miss the two second signal, so check for power when car won't start-when pump won't turn on-and with the engine cranking. If you have a signal then and still no pump coming on, then you must have a failing pump.
But if you have NO power to fuel pump wire with engine cranking, then it is a problem elsewhere-probably the pump relay (try a new relay if you haven't already). That relay is signaled by the engine computer when key is turned to on or when engine cranks . so you could do some testing at the relay if needed.

Have you checked the fuel pressure since you replaced the pump ?
Did you jumper the relay to make the pump run and see if the engine will run ?

Yes. The switch is usually located around the passengers kickpanel. There should be an access hole to press the button on the switch. Sometimes the part is just above the carpet and sometimes you have to remove the kickpanel. If you are unable to find this switch on the passengers side,then look on the drivers side kickpanel.

Under the hood is a Powerbox. The shutoff switch (inertia switch) gets its power from the Fuel pump Relay after the Ignition is turned on. If resetting the shutoff switch does not help, your fuel pump Relay may be bad. On some Ford models, the horn Relay is the same Relay used for the fuel pump. This would allow you to swap and test before buying a new Relay.

Good info on the PATS / theft light. Looks to be the PATS / HEC operation is functioning correctly

The Fuel inertia switch only cuts power to the fuel pump, so if tripped, the truck would have a crank no start issue. Do you have a crank no start, or no crank issue.

To reset, just press down on it. To check if the switch is tripped, check for power at the connector to the fuel inertia switch

Engine compartment fuse # 10 ( 20A ) to the fuel pump relay -> Dark Green w/ yellow stripe wire to the fuel inertia switch -> pink w/ black stripe wire to the fuel pump module.
Check the pink w/ black stripe wire to ground with a meter for power, with the key in the run position.

If you turn the key from off to run ( do not start ) you should hear the fuel pump cycle ( hum, then turn off ).

Could be an issue with the fuel pump relay ( my '01 had a crank no start at ~ 35K miles, bad fuel pump relay ). I proved this out ( after a stupid ID10T error in my diagnoses process ) by jumpering the normally open contacts in the fuel pump relay socket, and then installing the trailer tow reverse circuit relay into the fuel pump relay socket ( same full size Ford Relay ).

Jumpering the fuel pump relay in the relay socket ( remove relay and use jumper wire ), red line


If you have a no crank issue, could be the DTR ( Digital Transmission Range ) sensor on the driver's side of the trans is out of alignment.

Check the start motor relay ( on the firewall on the passenger side ) for power on the Tan w/ Red stripe wire when the key is in the start position ( this is from the ignition switch through the DTR when in park or neutral to the starter motor relay ).

You can test another route, turn the key to the run position, and apply power to the Tan w/ Red stripe wire on the starter motor relay in the engine compartment on the firewall. BE CAREFUL, the motor should turn over, keep clear of moving parts.

Post back a comment to this problem with the results of the testing.

Thanks

Turn the key to the ON position without starting the engine. You should hear the fuel pump running for 5 seconds if working. This primes the gas to the injectors when doing this. If not heard running check the oil pressure switch for the 12 volts needed to run the fuel pump starts there on that harness. When the engine starts and the oil pressure reaches the normal pressure the computer shuts off that circuit and turns on the fuel pump relay to run the pump. The relay stays on till you shut the engine off

Check to see if there is any power getting to the fuel pump, if there is 12 volts going to the fuel pump then replace the pump, if there is no voltage present, the problem could be the fuel pump relay, a fuse, or a break in the wiring.

before you drop tank again, check fuses & relay.then disconnect fuel line @ filter turn key to on position should hear fuel pump run and get gas stream out of line. if no flow from line new pump faulty be sure & remove negative battery cable first good luck.

A relay, when jumpered will either close the pprimar circuit closing the secondary circuit and by passin either one will keep the fuel pump runing.. A t relay has two power sources going into it.. when the light circuit is closed it closes a heaveir circuit to handle the current draw of the fuel pum.allowing the pump to run. Yhe primary circuit is key actuated and when secondary engages ,iys oiwer is always present in the relay polug. in power is connected to the fuel pump wire when relay poibts close. On the fuel rail, there is s valve like a tir air stem remove screw on cap. rurn on key and then depress the vlalve center like letting air out od a tire. Yhat shoul purge any air in the system and confirm you are getting ful yp the injrcyors. I hop yjos helps. good luck

it is the fuel pump for sure. If you can hit the tank and get it to run it is the pump. this drain back (hard start after sitting) is a fuel pump issue as well