truck wont idle

[huntnfmly]

Pulling my hair out. I have a 89 Chev pu 305 tbi truck idles when cold when it warms up idle slowly drops then dies I have replaced fuel pump during. A hunting trip that's another story. Also replaced iac it just happened one day any help would be great thought I would get some opinions before I run it to the shop and pay their diagnostic. Fee

[Bulldozer]

Being TBI you probably have a vacuum leak somewhere.

[jrebel]

I had a ford escort that would do that and it took me forever to find the problem.  Ended up being a vaccuum hose that went into the top of the valve cover of all places.  It cost me a whopping $2 to fix it.  It would run find when cold then once it was warm it would die every time I came to a stop unless I kept the idle up.  I am no mechanic and I have know Idea why that would do that, but it did.  So maybe check all your vaccuum hoses....usually you can hear them drawing air and kinda hissing. 

Good Luck

[coachcw]

make sure that you have a good vaccum supply to the map sensor, they plug up in the throttle body . also check the pcv system to see that its not plugged up in the tbi. if it runs well at road speeds the reat of the tune is most likley ok. at idle your iac counts should be around 15-20 counts .if it's down around zero then you probilly have a vaccum leak .good luck.

[Widgeondeke]

I had an 89 GMC. Did the same thing. I recall it was a vacuum related leak and the TBI.

[luckyman]

Check the egr. They Can carbon up and cause that.

[huntnfmly]

Thanks everybody. Is there. Any problem with disconnecting vacuum lines going to Tbi. And squirting Carb cleaner to clean out?

[huntnfmly]

I was just checking the egr.I unplugged it and there was no change then I sprayed starter fluid on it and there was no change . That should of acted. Like a vacuum leak and revved up shouldn't. It have? I hope so maybe. That's the issue

[Buckmark]

I was just checking the egr.I unplugged it and there was no change then I sprayed starter fluid on it and there was no change . That should of acted. Like a vacuum leak and revved up shouldn't. It have? I hope so maybe. That's the issue

Nope, if the valve is closed it wont rev up, and it should be closed at idle

[RoyBoy]

did you check your  0 2 sensor? mine broke in my 94 chev and it wouldnt idle either