88 5.7 fuel pump problems

[Chris_Standard]

hey guys i hope somebody can help me out here, recently my truck quit running and the fuel pump is not coming on at all, now the fuel pump is good i just put it in a couple of months ago, i'm not getting power to it though, the fuse is good and i replaced the relay, also another thing i thought was odd is that my fuel gauge reads full all the time now and i know for a fact it has below half a tank, somebody told me it could be my oil pressure switch but if i bypass it all together the fuel pump stays on all the time without the key turned on, and i don't really see how that would mess with the gauge, i would appreciate all the advice i can get, this thing has really confused me.

 

[FastOrange]

How did you bypass it? i have mine bypassed so the pump kicks on when i turn the key.

 

[Chris_Standard]

i just ran a jumper wire from one port to the other on the plug, which i know is bad haha it was just a test before i did it the right way

 

[FastOrange]

which plug? i can show you how i did mine.

 

[Chris_Standard]

the plug that goes into the oil pressure switch right behind the distributor, man any help i can get right now i would appreciate, and i'm not very good with TBI stuff. i just wanna get this thing back on the road

 

[FastOrange]

the plug that goes into the oil pressure switch right behind the distributor, man any help i can get right now i would appreciate, and i'm not very good with TBI stuff. i just wanna get this thing back on the road

its alot easier then that.

1. Remove the plastic cover under the hood, that hides the fuel pump fuse and relay
2. Locate the Fuse Plug thats on the far left
3. Take out the fuse.
4. Take a piece of wire and touch the + on the battery on one end and touch one of the terminals where the fuse went, ONE will kick on the pump instantly, Mine was the right hand side wire.
5. Cut the OPPOSITE wire, so you can reuse the fuse/Holder
6. Wire it up to 12V+ Switched power.

This should make your fuel pump kick on as soon as you turn the key, no relay or Oil Pressure switch needed.

Wire is the blue one added to the fuse holder in this picture, blue wire is going to Switched power, other one heads into the stock harness, didnt need to to touch it at all.

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[Chris_Standard]

alright thanks man this is a great idea i'll try this whenever i work on it again do you think that would have anything to do with my fuel gauge not reading right? it says i have a full tank when i know i've only got a little below a half of a tank, sorry if these are dumb questions i'm just lost man

 

[FastOrange]

alright thanks man this is a great idea i'll try this whenever i work on it again do you think that would have anything to do with my fuel gauge not reading right? it says i have a full tank when i know i've only got a little below a half of a tank, sorry if these are dumb questions i'm just lost man

the gauge is probably the level inside the tank.

 

[Chris_Standard]

i pulled the sending unit out of it thinking that my pump had just went out and the tank is for sure a little less than half full but the gauge inside the truck reads full

 

[Johnbalderas90k1500]

the fuel sending unit is probably bad. if you unplug the connector to the unit the gauge will show completely full. the sending unit is a variable rheostat and the higher the resistance throught the circuit the more full your gauge is gonna say. 1/2 a tank will be around 44 ohms and full is around 88. you can test the unit by using an ohmeter and putting the leads on the two wires and raising the float up. the resistance value should increase steadily, if not it is probably bad. its a two prong connector