secondary fuel pump circuit fault?

[PFC Laird]

So i pulled codes on my truck and got 10 and 542. Now from the threads i found here about 542 i'm just gonna assume it's a common thing for the inertia cut-off to go bad after a while. Is this the normal cause for this tho?

also i was unable to find KOEO code 10 in anything.

 

[RonD]

I wouldn't say it's normal, inertia switch should last the life of the truck.
You can use a jumper wire to by-pass that switch, to see if it's the problem.

I assume you have a no start condition.

There is also a Fuel pump relay that does fail with age.
In your '94 it should be located in or under the power distribution box in the engine compartment.
Open the box if you don't see the square box relays inside then they will be under the box.
It is easier if you remove the screws holding the box to get easier access under it, the Green connector is the Fuel Pump relay.
If you use a voltage tester on the 4 connectors for the relay you can find the ground pin, the ECM pin, the 12v pin and the out to fuel pump pin, if you jump the 12v pin to the out to pump pin the fuel pump should start, assuming inertia switch is passing voltage.
If pump works then relay is probably bad.

There are cheap relays that can last a few months to a year and there is the Ford relay, which has lasted 19 years, choice is yours.

 

[LIMA BEAN]

Swap the headlight relay into the fuel pump relay if it works drive down in the daylight and get another relay for the headlights, should be the same one.

 

[PFC Laird]

I assume you have a no start condition.

yea i've had this truck since 06 and actually had this intermittent problem for a long time but ever since i dropped my drive line. it was the final nail in the coffin.

(long story)

i'll try the relay out tho in the morning.

 

[LIMA BEAN]

Dayam son! That lift the wheels off the ground? I would dam sure scope the under carriage wiring under there. And yes inertia switches go bad alot, its an electrical switch so if thats it buy a good one... your life and others may depend on it in a crash. Post up and let us know what you find.

 

[PFC Laird]

well i've replaced the pump relay and no dice....fuel squirts out of the rail every time i prime it so i don't think it's the inertia switch. i don't think my dad was getting a spark off it tho before, now that i think about it.

Dayam son! That lift the wheels off the ground?

yes....yes it did lol

 

[PFC Laird]

Ya i'm definitely not getting a spark either. but 542 is the only code i get from it.