TBI Starting Trouble

[HuskerBlazer]

Alright, just yesterday my Blazer started acting funny on start up. Doesn't want to keep running and the idle seems really low. Specs: 90 TBI stock. If I rev it on start-up it will eventually stay running. I would guess clogged injectors, but the weather just changed the day it started acting funny. Cold and rainy. Could this be water or temp change? Any guesses?

K-5...Soccer moms inquire within.

 

[scooby]

any dummy lights on?
check engine? etc..
u pump the gas while starting?( u shouldnt do that )
u ever use a fuel system cleaner? (u should do that )
u change ur fuel fillter?? ( u should do this too )



support ur local parts guy, bring beer.

 

[Twiz]

Runs O.K. but won't idle?
Kinda sounds like a IAC (Idle air controler) problem. Possibly cloged passeges, or a problem with the motor it's self. (code35)

I personaly haven't messed with IAC much, thats a drivability tech thing. (not my thang) But, I know what thay are and how they work. The IAC is basicly a needle and seat, controled by a motor, and the moter contoled by the ECM or PCM. It opens and closes as needed to "bleed" more or less air to the intake and therfore controls the idle speed.

A little better discription of the problem would be helpfull.
The TPS (throttle position sensor), MAP sensor (mas air pressure), CTS (coolant temp sensor) and O2 sensors are needed to adj idle speed.

<font color=blue>Twiztid</font color=blue>

 

[Thunder]

You really need to find out if there are any trouble codes stored on the computer. Having a code scanner is almost a must when trouble shooting computer controlled TBI. It really helps narrow down where the problem is.

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[solowookie]

I've had this same problem on both my k5's... one had some bad vaccum lines, and the other one had a bad EGR valve...

you might want to start out by just checking that all your vaccum lines are hooked up, and hooked up correctly... then I'd get the code.

<font color=blue> Jeff - may the force be with you</font color=blue>
<a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>

 

[Twiz]

Good reply Jeff. That brings up ALL the other mechanical possiblilittys. PVC, EGR, Linkage, etc...

We need alittle better discription of the problem. The part about "as the climates changed, It started this problem" leads me to belive it -might- be a sensor problem. But I could be wrong...

<font color=blue>Twiztid</font color=blue>

 

[HuskerBlazer]

Well I checked the spray of the injectors last night, the seemed to be spraying fine under load by kind of spotty at idle. By kind of spotty I mean seemed to be streams going down the sides of the throttle body, but not streams coming out of the injectors...kind of like condensation on a window. Probably could use a new fuel filter. I stopped running fuel injector cleaner when I was driving on the hiway a lot (thought it was waste). Maybe I should run some more through.



K-5...Soccer moms inquire within.

 

[HuskerBlazer]

Oh yeah...I've never used a code scanner (never really had a problem with this truck before, and this is my first computerized truck). Where can you pic up the scanners? Are they parts store things or go to the dealership things?


K-5...Soccer moms inquire within.

 

[Itali83]

Does it only idle rough or stall when you first start it up, then after like a couple mins of you revving it up will it finally idle by itself??? Does it crank and crank and crank and then finally start?? If it does, like mine did, I replaced the water temp sensor for the computer, not the guage, and it took care of all my hard starting, not idling when cold problems, it is the sensor on the intske manifold right by the thermostat housing. Do what the others say first, but It could be that sensor.
Ben 87 Jimmy
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[yeild2me]

mine had a rough idle but ran good at any other throttle position, and after i changed plugs, wires, cap, rotor, air filter, fuel filter etc., it turned out to be the gasket under the TBI. spray a little carb cleaner at the base and see if the idle changes. 3 bucks for a gasket and three bolts to swap cured it.

350 TBI, 700R-4, NP241, D44-14FF, 4:10's, 38.5 TSL/SX's, full conv., full cage
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[KRAZIE87K5]

No one recommends the fuel pump itself? The last TBI I had, the only issues I had with it were the injectors grew some sort of cancer that forced me to replace them, and the fuel pump died. 3 TIMES. You might want to look into that.

<font color=red>GOT MUD???</font color=red>
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454/TH400/NP205 - 14BFF/D60/w/ 4.10s

 

[HuskerBlazer]

No its more like it will crank and turn over but not stay runnning unless I rev it. After a few minutes of revving it will idle, but it seems like lower RPM than before (don't have a tach, but I'm sure its lower). Like I said before, when giving it gas it seems fine. I would think this MAY rule out the fuel pump...but maybe not. Guess I'll check the easy stuff first (fuel filter, dirty injector, TBI gasket) and work my way up.


K-5...Soccer moms inquire within.