Idle Issue

[Engir]

Some of this is going to sound strange I think. After I replace the brake booster and took away the air leak the high idle stopped working. My 4.0 1987 XJ will not idle at all on start up and when it is warmed up and I take my foot off the pedal it goes to an idle of about 500 RPMs on the tach and will eventually die. I know my pump is not holding pressure, the sending unit is bad also, I have a new one but no way to get the gas out of the tank to change it (I am in Costa Rica) I have looked over the throatle body and I do not see any where to set the high idle and idle can someone help I know there has to be a place to do this I cannot find it, please and thank you.

PS, there are no vacuum leaks, I have done a visual and audio inspection of the engine.

 

[superj]

your idle control valve And its area of the throttle body are clean?

 

[Engir]

your idle control valve And its area of the throttle body are clean?

Yes, I sprayed the throttle body down with carb cleaner about a week ago thinking it would help with the issue and it did nothing.

 

[superj]

maybe your idle control valve is no good anymore?

the pump holding pressure, do you mean its not putting out the required pressure for running or it bleeds down after you shut the truck off?

if it bleeds down after shutting off, that won't effect the running issue but you can buy little in-line check valves and put it in the fuel line form the pump to the fuel injectors and it will stop the fuel from draining back.

inline fuel check valve - Google Search

i had to use one on a bmw that kept losing pressure when turned off. i didn't want to pay 150 bucks for a new pump when it was just the built in check valve that had stopped working. i put that right at the line where it connects to the fuel pump and the car went back to starting like normal

 

[Engir]

maybe your idle control valve is no good anymore?

the pump holding pressure, do you mean its not putting out the required pressure for running or it bleeds down after you shut the truck off?

if it bleeds down after shutting off, that won't effect the running issue but you can buy little in-line check valves and put it in the fuel line form the pump to the fuel injectors and it will stop the fuel from draining back.

inline fuel check valve - Google Search

i had to use one on a bmw that kept losing pressure when turned off. i didn't want to pay 150 bucks for a new pump when it was just the built in check valve that had stopped working. i put that right at the line where it connects to the fuel pump and the car went back to starting like normal

I watched some videos on YT and checked the pressure on the fuel rail there is a valve to dump the fuel if you are disassembling and there was no fuel in the rail the video said this is because the pump is bleed back, not holding pressure also the sending unit is not working I ran a check on the wiring using a multi-meter and determined that the sending unit is bad so I bought new unit on Amazon some months ago I only need to fuel level down so I can pull it from the tank without fuel going everywhere. Also on start up each time I can here the pump running and have to wait until it stops for the motor to start so it is bad bleeding back from lack of pressure.

 

[Engir]

maybe your idle control valve is no good anymore?

the pump holding pressure, do you mean its not putting out the required pressure for running or it bleeds down after you shut the truck off?

if it bleeds down after shutting off, that won't effect the running issue but you can buy little in-line check valves and put it in the fuel line form the pump to the fuel injectors and it will stop the fuel from draining back.

inline fuel check valve - Google Search

i had to use one on a bmw that kept losing pressure when turned off. i didn't want to pay 150 bucks for a new pump when it was just the built in check valve that had stopped working. i put that right at the line where it connects to the fuel pump and the car went back to starting like normal

Where is the idle control valve and how to test it?