I tried to post this last night from home, but I don't see it this morning at work. If this is a duplicate post, I apologize.
Okay, I'm about at my wits' end, and I'm about to start pulling out > hair.
> If anyone has ANY suggestions, they would be GREATLY appreciated. This is
> my first "play" vehicle with TBI, so there's a bit of learning involved
> here. Bear with me.
>
> Vehicle - 1988 Chevy K1500 350 (5.0L) TBI 4x4
>
> Problem - will not start
>
> Here's the low-down. The truck had set for 2 years when I bought it.
> Basically, I charged the battery and it started right up. I noticed that
> the idle was a little high, but other than that, it seemed to run fine. I
> ran a couple of tanks of gas through it and all seemed to be okay, but I
> noticed the idle seemed to be getting higher. It was getting tough to
> hold it back at a stop light, so I figured I should do something about it.
> The first thing I did was I had the fuel system "cleaned" or "flushed", I
> can't remember what terminology they used. It seemed like it helped a
> little bit, but after a very short time (less than a day), they idle
> climbed back up to where it was, if not higher. The next thing I did was
> I replaced the IAC. Again, no help. Then I general tune-up. No help. I
> continued to drive it, and it seemed to get worse. Then one day I noticed
> it was very difficult to start. Once I got it running, I got about a half
> mile down the road and it quit. It smelled like it had flooded itself
> out. I got it started again by holding the throttle to the floor, got it
> back home and parked it. I replaced one part at a time, and started it
> after each replacement to see if it was right. Each time I tried, it
> seemed harder to start. To me, it seemed like it was flooding out. Now,
> it will not start at all, and rarely even "hits". I've checked the
> injectors, and they're both giving what appear to be good, symmetrical
> cones of fuel. I've checked the electrical system all the way to the plug
> and it seems to be getting fire. I read in this NG about these engines
> being susceptible to gasket deterioration between the TBI and manifold.
> After reading that, I just presumed this was the reason for my high idle
> (getting worse) and then to the point of it wouldn't even start. I picked
> up a gasket today, confident that it would solve my problems. I replaced
> it, and still nothing. I'm at the end of my rope here lol. Any advice is
> welcomed. Here's a list of everything I've replaced to date -
>
> IAC valve
> MAP sensor
> distributor rotor button
> distributor cap
> spark plugs
> plug wires
> air filter
> fuel filter
> ECM
> O2 sensor
> TBI gasket
> ignition coil
>
> I checked the TPS with an ohm meter and it tested fine
> I moved the crank shaft so the harmonic balance was at 0 degrees and
> checked the distributor to make sure it didn't jump time - seems fine.
> I've tested the spark using a screw driver in the end of the wire and let
> it go to a ground. Did this on cylinders 1 and 3, both were fine.
> I precisely marked the distributor location, and moved it ~10 degrees in
> each direction to see if it's a timing issue - no effect what so ever so I
> moved it back to its original setting.
> Another reason I thought maybe it was a vacuum issue is because the inside
> air controls will not switch to "defrost" - continues to blow through the > dash vents
> I've checked ODB1 codes early on and it gave me codes in the 40's - lean
> and rich mixtures, and a reference to the MAP sensor. No real help there. >
> At this minute, the engine will not start, but after every 10-20 > seconds
> of cranking, it'll give a quick little "hit", but never start. Sorry for
> the long post, but I wanted to be as detailed as possible. Thanks for > your help!
>
> - Jeff
>
>