Idling issues

[Reid90]

I have had idling issues on my 90 chevy k1500 for about 6 months now and i cannot figure out what is the problem. the other day I had just drove for about half hour and when I got home I got out of my truck and I heard the fuel pump priming when the truck was running I have about half a tank of gas left and it idles very low. is it time to replace the fuel pump? Sometimes when I'm sitting at a stop light the truck will idle so low it almost dies and then rev itself back up to normal and repeat. (I recently rebuilt the tbi)

 

[Schurkey]

90 chevy k1500

WHAT ENGINE? Diesel? V-6?

I heard the fuel pump priming when the truck was running

What is the difference in sound between a pump "priming" and a pump "running like normal"?

is it time to replace the fuel pump?

What is the fuel pressure at prime, and under load?

How old is the fuel filter?

Sometimes when I'm sitting at a stop light the truck will idle so low it almost dies and then rev itself back up to normal and repeat. (I recently rebuilt the tbi)

Connect a scan tool, verify ALL the sensors and computer outputs.

Did anyone dick with the base idle screw, hidden behind the "tamper-proof" cover? Doing so rarely ends well.

How old are the usual "tune-up" items and procedures? Cap, rotor, plug wires, spark plugs, PCV valve, O2 sensor? Is the ignition timing verified correct, including the electronic spark advance? Does the EGR work properly? Vacuum hoses in good condition, connected where they should be?

 

[Reid90]

It is a v-6 I don't know what the difference is when the pump is running or priming I just have never heard the pump on before when the truck was running I do not know what the fuel pressure is, and the fuel filter is new. I don't know if anyone tampered with the idle screw. I Did replace the EGR valve, I am pretty sure vacuum hoses are good and I know they are all connected.

 

[Schurkey]

It is a v-6

OK.

I don't know what the difference is when the pump is running or priming I just have never heard the pump on before when the truck was running

Of course the pump runs when the engine is running.

I do not know what the fuel pressure is,

Good time to find out.

I don't know if anyone tampered with the idle screw.

I'm pleased you didn't mess with it during the "overhaul".

I am pretty sure vacuum hoses are good and I know they are all connected.

But are they connected to the places they're supposed to connect to, or has someone scrambled the vacuum hoses from one nipple to another?

Connect a scan tool, verify ALL the sensors and computer outputs...

...How old are the usual "tune-up" items and procedures? Cap, rotor, plug wires, spark plugs, PCV valve, O2 sensor? Is the ignition timing verified correct, including the electronic spark advance? Does the EGR work properly?

?