When I start my 89 PU with the 4.3L it instantly revs up reall really high for about 10 seconds, then goes to a normal idle. Anyone had this? Know what it could be caused by? We believe its in the fuel injection (TBI) probably.

high cold start idle is normal. if it stays there then you have something to worry about. my truck with a cold start will idle at 1500 rpm and slowly lower to 900 rpm within that 10 second range. check all your vacuum and fuel lines. make sure your fuel pressure regulator is working.

Understand that, but it does it everytime it is started, even when hot. That's what is kinda confusing.

How high does it rev to?

Remove and clean out the Idle Air Control valve on the throttle body. Also spray cleaner into the IAC opening on the tbi and clean it out real good.
Restart and put in drive so the Ecm can do a relearn on the IAC.
Post here if it helps or not
Fireplug

Excellent advice.

I didn't know the 89 had one.

Yo BLAZERLT The dude said 4.3 with TBI you a##wipe.
I have tried to be nice to you 2 times now but you insist on being a smartass. Did you leave the nut house to soon??? How the hell do you know if he might have had a engine change???? YOU DONT
Learn to f##king read before you mouth off he is asking about a tbi system!!!!!!!!
Sorry about the explosion but my god some people just never learn to GROW UP.
Ok I know whats going on here you are afraid I am taking over and that you might be forgoten.
Its ok there is room for everyone m8
Just so you know1988: An optional 4.3L V-6 engine with EFI was out there m8

Yo BLAZERLT The dude said 4.3 with TBI you a##wipe.
I have tried to be nice to you 2 times now but you insist on being a smartass. Did you leave the nut house to soon??? How the hell do you know if he might have had a engine change???? YOU DONT
Learn to f##king read before you mouth off he is asking about a tbi system!!!!!!!!
Sorry about the explosion but my god some people just never learn to GROW UP.
Ok I know whats going on here you are afraid I am taking over and that you might be forgoten.
Its ok there is room for everyone m8
Just so you know1988: An optional 4.3L V-6 engine with EFI was out there m8

WTF bro....

I honestly meant I didn't know they had one and I was complimenting you.

Why are you yelling at me for? I was agreeing with you????!!!!!

Then you have a poor way of saying things m8.

Excellent advice.

I didn't know the 89 had one.]
Sounds to me like a smart remark like yo dude they did not have a 4.3 in 89.
Its all in how some words things .
I cant tell by reading a computer screen how that was meant to be taken. I took it the wrong way
Sorry
Fireplug

Yea,

I honestly didn't know they had one.

When I say "Excellent Advice" I mean it.

I still don't know what I said that could be taken as rude in any context. I even had six friend of mine check out the thread and they are confused as to how you derived attitude from it also.

All is good and swell in chevy land.......:D

Thanks for the input. If you want to know, it revs high enough to spin the tires in gravel if it is put into gear while revving high. Any kind of time estimate on the IAC or difficulty...I'm pretty strained for time right now.

Find it, remove it, clean it install it.

Very easy and should take no more than 10 minutes max.

Use throttle body cleaner and a old toothbrush to get rid of all the carbon.

Thanks for all the help. Hope it works.

Find it, remove it, clean it install it.

Very easy and should take no more than 10 minutes max.

Use throttle body cleaner and a old toothbrush to get rid of all the carbon.

Hey Guys !

I have this same problem, I have done wires cap rotor plugs, fuel pump and checked for vacuum leaks. 2 Years I had high Idle when I would start. I read this post, and though, what the he##.

It worked, the Idle is low at start, the pintle was clogged with crap couldnt move it used release all and removed the debris, I was finally able to turn the pintle.

Thanks !!!!

Al

how high is the startup idle?

how high is the startup idle?

The Idle was quite High around 2000, but it would come down to about 1200, which still seemed high.
After I cleaned the IAC It starts around 800.

Much nicer

Yip, also reset your computer.

Check all vacuum lines for leaks around where they connect.