Hey!

I have searched, and have found a little bit of info related to this, but no exact answer. Can you help?

PROBLEM:
My 1990 K5 Blazer with stock 350 TBI and 193,000 miles will not idle. It will not start unless I keep my foot on the throttle a little. As long as I keep my foot on the gas, it runs fine. If I let off, it will die immediately.

SITUATION:
This just happened this morning. My K5 has been running and driving fine - I last drove it to pull my car trailer and a Pinto wagon on Saturday. I started the K5 this morning and moved my car trailer around, then turned off the K5 so I could unhook the trailer. Decided I would rather leave the K5 running with the A/C on, so I tried to start it back up. No start. Will only start if I keep my foot on the throttle. Had to drive my Suzuki Samurai to work.

QUESTION:
Any ideas? I am going to pull codes tonite and see if there is anything there. Does this sound like an IAC problem? It IS getting fuel, and again, it runs fine otherwise, just won't idle or start without my foot on the gas.

Thanks!
Richard

 

When was the last time it had a tune up? A dying fuel pump and or glogged fuel filter will cause the problemrs you stated. How are you sure you are getting enough fuel?

 

I can hear the fuel pump running, but I have not tested fuel pressure or anything.

It has been at least 3 years since I changed fuel filters, and I even have a new one sitting in the center console, so I'll do that tonite, along with checking the codes. I will also check plugs, wires, cap, and rotor if that's a good place to start looking.

Thanks!!!
Richard

 

QUESTION:
When I spray throttle body cleaner into the IAC port with the engine running, should it pool in there, or should it drain out? It is pooling in there. Does that mean it is clogged, or that the IAC is not moving?

I checked some stuff last night, but it is still not right:
1) Replaced fuel filter - it needed this bad, you should have seen the nasty black gas in in the inlet side of the old filter. But did not fix problem.
2) Pulled air cleaner - injectors seem to be firing fine, but I have no other vehicle to compare to.
3) Noticed that gasket around base of air cleaner was coming apart. Looked like a piece of it might have gotten into the IAC port. Removed IAC - it was NASTY. Sprayed IAC and port with throttle body cleaner and got a bunch of crap out of there. That still did not fix the problem.
4) Checked codes, no codes found.
5) I kept my foot on the gas to keep it running, and I let it warm up all the way. It finally would idle, but lower RPM than usual, and I could make it stumble by turning on/off the A/C and putting it in/out of gear. It would start on its own (without my foot on the gas) about every other try, but even then it did not start right up like it used to.

I can't work on it again until Thursday night, and maybe not even then. I'm going to go ahead and pick up new plugs, cap, rotor, and O2 sensor, and order new plug wires (I am sure it needs all of these anyway, regardless if this is the actual cause of this problem or not). I'm also going to call the Chevy dealership about getting a factory service manual for my K5...

Thanks!
Richard

 

Did you already try to adjust the TPS and IAC by the way listed on the tech board?

Here is the link:

https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

 

Disconnect the Coolant temp sensor. And start the car. If it behaves the same way, that's probably your problem.

 

????
Are you saying that with the sensor disconnected the car will still run crappy, or will it smooth out? Not meaning to be critical, just wondering what you meant.

 

Unplug the CTS. If your car starts up right away, then it's a bad CTS.

Check TPS, MAF/MAP, and o2.

Although, if the sensors are bad, it should throw a code.

 

I had a pickup truck with VERY similar symptoms (but it was a 4 banger, mind you) and the problem turned out to just be a fried sparkplug. HTH...

Bruce (90RS305)