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Bad fuel pump/relay???

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Old 12-15-2022
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Bad fuel pump/relay???

Alright i think ive asked this before but im going to again.

sometimes when i turn my key the fuel pump makes little to no sound and when i try to start it it might sputter for half a second or die. These last two days its done it a couple times but instead of completely cutting out it runs like its on 2 plugs until i rev the crap out of it.
It did it once mid drive.

my remedy is going to the under the hood fuse box, removing the fuel pump relay and either tapping it and putting it back or just putting it back. OR i swap that relay with either the identical pcm relay or the W.A.C system relay.

after i do the relay SWAP and shut the truck back off ot wont work again until i put the original relay back.

my question is as follows
is my issue the relay, or the connection inside the fuse box? I genuinely dont think its the pump.

i would also like to add that the fuel gauge doesnt work but it did for like two days after i had to re strap my gas tank…

any help is needed and if it is the little connectors can i fix it cheap?
 
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Old 12-15-2022
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You can swap relays, need the year of Ranger and engine model to say which relays are interchangeable
Don't want to swap PCM relay, for sure, any other relay is fine

Simpler method would be to put a Test light in the cab, passenger side hooked to Inertia switch so you can see the light while driving
Inertia switch gets 12v from Fuel Pump Relay/fuse and passes that on to fuel pump

Test light should activate for 2 seconds with key on, or each time key is turned from OFF to ON, its a safety thing
Then once engine is above 400rpm test light will come on full time
Test light will tell you if relay, wiring, or computer is shutting off power to fuel pump, if not then its a fuel pump issue

Fuel tank pump and sender/float each have their own Ground wire, if ground is an issue then neither would work reliably


Engine struggling to stay running on start up could mean your system is losing fuel pressure with Key Off
Not unusual, fuel pressure regulator or pump itself can leak fuel back into the tank, so no fuel lost but no pressure for start up

Try cycling the key on and off 3 times, so 6 seconds of run time for fuel pump, that should put pressure at 30psi if it was 0psi, see if startup is better
1986 thru 1997 uses 35psi pressure
1998-thru 2011 uses 60psi pressure

You get about 10psi pressure in the 2 second run time
 
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Old 12-15-2022
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Originally Posted by RonD
You can swap relays, need the year of Ranger and engine model to say which relays are interchangeable
Don't want to swap PCM relay, for sure, any other relay is fine

Simpler method would be to put a Test light in the cab, passenger side hooked to Inertia switch so you can see the light while driving
Inertia switch gets 12v from Fuel Pump Relay/fuse and passes that on to fuel pump

Test light should activate for 2 seconds with key on, or each time key is turned from OFF to ON, its a safety thing
Then once engine is above 400rpm test light will come on full time
Test light will tell you if relay, wiring, or computer is shutting off power to fuel pump, if not then its a fuel pump issue

Fuel tank pump and sender/float each have their own Ground wire, if ground is an issue then neither would work reliably


Engine struggling to stay running on start up could mean your system is losing fuel pressure with Key Off
Not unusual, fuel pressure regulator or pump itself can leak fuel back into the tank, so no fuel lost but no pressure for start up

Try cycling the key on and off 3 times, so 6 seconds of run time for fuel pump, that should put pressure at 30psi if it was 0psi, see if startup is better
1986 thru 1997 uses 35psi pressure
1998-thru 2011 uses 60psi pressure

You get about 10psi pressure in the 2 second run time
could you elaborate on the test light? Unless theres another forum on it, I would like to try it to see

 
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Old 12-15-2022
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12volt test light, seen here: https://media-www.canadiantire.ca/pr...edefbcc0b5.png

Used to test if wires have voltage or a good ground

In this case use the clip end on a bolt or exposed metal by/under glove box where inertia switch is located
Push the "pointed end" in to one of the terminals on the inertia switch, use tape to hold it in place
Turn on the key, light should come on and go off after 2 seconds if its hooked up correctly
Should stay on full time when engine is running

Inertia switch is located on the firewall under glove box, looks like this: https://qph.cf2.quoracdn.net/main-qi...b1589f8c750-lq

Green wire comes from the relay
Pink wire goes to the fuel pump
either should have the 12volts when relay is closed
 

Last edited by RonD; 12-16-2022 at 09:02 AM.
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