350 TBI Woes

[Notaduramax]

Hey guys, Ive used this forum in the past and have been able to find answers for what I need but I cant seem to figure out whats going on with my truck now so I finally joined up so I can post. So heres what I got. Back in december I bought a 1988 k1500 350 TBI. Drove it home an hour and a half with no issues. The truck ran great for about a month and then I started to notice that it wouldnt run quite right on the highway and would idle rough when I came off the highway until I shut the truck off. This would be accompanied by the SES light coming on. However, as soon as I would turn the truck off and back on, the SES light would be off and it would be back to running smooth. This makes it almoat impossible to scan the code to see whats wrong. After I noticed this I tried to stay off the highway as much as I could because it wouldnt do this driving through town. Well one night about 2 weeks ago I got on the highway and got off at the next exit to go to a friends house. As I got off the ramp, the truck started to idle horribly and made a very loud screeching sound. I immediatly pulled off the road and shut the truck off. I let it sit for a few minutes then tried to start it again. Starter tried to turn it over and then just started clicking. Called my buddy over and had him crank while I got under the truck and saw the starter arcing on itself. Ended up getting it towed home and pulled the starter. It was definitely toast so I purchased a new one as well as a new positive battery cable and installed them. Now when I try to start the truck I get nothing from the starter, not even clicks, but all lights and accesories work. Ive checked grounds, checked connection to new starter and they are all good and tight. Even when trying to jumpstart the truck I get nothing. I havent got the chance to get under it with a multimeter yet to see if I have power to the starter but I will as soon as I can. So I guess I have two questions. First, what might cause my engine to run fine around town but then start acting up at freeway speeds? And second, what might cause a no crank with a new starter when the old starter was indeed getting power. I appreciate any help yall can give I just need to get my truck out of the driveway already

 

[Notaduramax]

Also forgot to mention, battery is less than a month old so I dont suspect a bad battery

 

[PlayingWithTBI]

I'm guessing you have a bad starter but, check voltage to the solenoid and to the starter motor to be sure.

Your highway problem could be running rich or lean. Even after you shut off the engine and the SES light goes away, you should be able to pull the MALF code by shorting pins A & B on the OBD1 connector under the dash on the left of the steering column. Then the SES light will start flashing 1 short pulse, a pause then 2 pulses, pause and so on. One pulse, then 2 pulses (code 12) means the ECM is working properly, any other pulses will be a MALF Flag, such as 44 (4 pulses then 4 pulses) = O2 lean, or 45 = O2 rich.

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[bowtie-72]

You heard a “screeching” sound before you shut it off? Are you sure the engine is turning free? You should be able to turn it over by hand with a 1/2” drive ratchet and socket on the crank bolt.

 

[Schurkey]

I started to notice that it wouldnt run quite right on the highway and would idle rough when I came off the highway until I shut the truck off. This would be accompanied by the SES light coming on. However, as soon as I would turn the truck off and back on, the SES light would be off and it would be back to running smooth.

I have an '88 K1500. I also had problems with high-speed misfire which got worse over time until the truck would stall. Eventually it would not re-start.

Replaced the distributor mainshaft (with new pickup coil and reluctor included.) Problem solved. However, I never had a SES light.

This makes it almoat impossible to scan the code to see whats wrong.

Don't read codes. Scan the data stream. This requires a scan tool, instead of a code-reader.

As I got off the ramp, the truck started to idle horribly and made a very loud screeching sound.

You heard a “screeching” sound before you shut it off? Are you sure the engine is turning free? You should be able to turn it over by hand with a 1/2” drive ratchet and socket on the crank bolt.

My truck did that, too. Alternator locked-up. ****** CS130 alternator, rear bearings are infamous for overheating and failure. Common as dirt. My starter couldn't turn the engine over until I replaced the alternator. Remember the movie "American Graffiti"? CS stands for "Chicken ****".

Of course, you could have a seized PS pump, a seized A/C bearing, or some other accessory or idler pulley besides the alternator. The air pump I removed from my truck after I blew up the engine needed two men and a donkey to turn (but I had no idea it was bad until I removed it, and that didn't happen for almost a year after the old engine popped--so maybe it rusted from non-use.)

Now when I try to start the truck I get nothing from the starter, not even clicks, but all lights and accesories work. Ive checked grounds, checked connection to new starter and they are all good and tight. Even when trying to jumpstart the truck I get nothing. I havent got the chance to get under it with a multimeter yet to see if I have power to the starter but I will as soon as I can.

The "big" question is whether you have proper voltage/amperage to the "S" terminal of the starter solenoid. This is likely to be a purple or pink wire. If you do, there's probably a fault in the solenoid or the starter motor. If you don't, I'd be looking at the ignition switch and the neutral safety switch/clutch switch, and the bulkhead connector block.

 

[rjteeter]

Someone ran an extension on my starter solenoid wire. Not to long after owning the truck the connection between the two wires corroded to the point the starter stopped working. X2 on checking for voltage

 

[Notaduramax]

Alright guys. Sorry for being MIA Ive been pulling a lot of overtime lately and havent had time to update you guys. So I figured out my starter issues. Turns out I connected the ignition wire to the wrong post on the starter. Got the wire on the correct post and it now starts with the key as it should. However, it still makes the screech sound as it warms up although not as bad as the night it happened. It almost sounds like bearings but I havent pulled the oil pan to confirm. Its not a constant screeching sound its more of an on, off , on, off sort of thing. Schurkey, can you explain in a little more detail the issue you had with a ****** alternator? I sure hope its a worn out accessory rather than bearings. I dont have the money for a new engine if the damage is severe

 

[delta_p]

I had my last alternator on my '96 make bearing noise at idle. it would go away as RPM's came up to drive. not a screech, more like a chirp,chirp,chirp. I could adjust the belt and get it to go away but it would come back. I finally just got rid of the alternator and got a new one rather than replace bearing.

 

[skylark]

Remove the belt and fire it up. That will tell you whether it's internal or not.

 

[xx94Z71xx]

the last time i heard a loud screeching sound like you describe it was the bearings in my water pump seizing up. X2 for pulling the belt and starting it.