What have you done to your square lately??

JamesSam · Saturday at 3:55 PM

Got ambitious this morning with a little free time. Took out the new IACV and cleaned the inlet. Did the paper clip idle set thing, mainly just to get the IACV to set itself. While the truck was warming up it sounded great. I went through with idle set and turned the torx screw on the TBI about a 1/4 turn counter clockwise while the engine ran high idle with the IACV unplugged. After that I turned off the engine, plugged the IACV back in and disconnected the battery for 30 seconds so the computer could reset then turned the engine back on. It was flooded, so I waited 30 minutes. Came back and the truck fires right up so I was naturally still feeling optimistic. I let it warm up and took it on a test drive. No improvements at all. It still studders under load, when you need to give it gas. It only drives normal when creeping along very slow. I still have a new O2 sensor to install but I'm afraid it won't help as I think this problem is bigger than that. I am still going to try and put the new 02 sensor on anyway but so far my last ditch attempt to throw parts at the TBI is not helping.

JamesSam · Saturday at 3:56 PM

Oh yeah, when the A and B ports are jumped for the codes it only reads code 12.

bucket · Saturday at 4:29 PM

JamesSam said:
Got ambitious this morning with a little free time. Took out the new IACV and cleaned the inlet. Did the paper clip idle set thing, mainly just to get the IACV to set itself. While the truck was warming up it sounded great. I went through with idle set and turned the torx screw on the TBI about a 1/4 turn counter clockwise while the engine ran high idle with the IACV unplugged. After that I turned off the engine, plugged the IACV back in and disconnected the battery for 30 seconds so the computer could reset then turned the engine back on. It was flooded, so I waited 30 minutes. Came back and the truck fires right up so I was naturally still feeling optimistic. I let it warm up and took it on a test drive. No improvements at all. It still studders under load, when you need to give it gas. It only drives normal when creeping along very slow. I still have a new O2 sensor to install but I'm afraid it won't help as I think this problem is bigger than that. I am still going to try and put the new 02 sensor on anyway but so far my last ditch attempt to throw parts at the TBI is not helping.

So I can't remember, have you ever tested the fuel pressure yet?

If I get some time later, I'll try to gather up all the related posts and put them in your own thread for you.

JamesSam · Saturday at 4:34 PM

bucket said:
So I can't remember, have you ever tested the fuel pressure yet?

If I get some time later, I'll try to gather up all the related posts and put them in your own thread for you.

I am borrowing a fuel pressure test kit from my uncle in law soon.

Mr Clean · Saturday at 4:37 PM

JamesSam said:
Oh yeah, when the A and B ports are jumped for the codes it only reads code 12.

Are you running Cats? Have you checked to see if it is clogging up?

Mr Clean · Saturday at 4:48 PM

Got a bunch of welding done today. Got quite a bit of the rear put back together. My welding game has improved a bit. Still have some welding to do, but it's coming back together. Also started another project while I waited on welds to cool. Started cleaning up the inner fender wells.

Mr Clean · Saturday at 4:50 PM

Inner fener well pics...

mtbadbob · Saturday at 5:41 PM

I discovered my radiator has developed a slight leak on the bottom side somewhere. F*@#!!! It's going to be below zero for a few nights, so I guess I'll deal with it when it warms up.

mtbadbob · Saturday at 5:47 PM

JamesSam said:
Got ambitious this morning with a little free time. Took out the new IACV and cleaned the inlet. Did the paper clip idle set thing, mainly just to get the IACV to set itself. While the truck was warming up it sounded great. I went through with idle set and turned the torx screw on the TBI about a 1/4 turn counter clockwise while the engine ran high idle with the IACV unplugged. After that I turned off the engine, plugged the IACV back in and disconnected the battery for 30 seconds so the computer could reset then turned the engine back on. It was flooded, so I waited 30 minutes. Came back and the truck fires right up so I was naturally still feeling optimistic. I let it warm up and took it on a test drive. No improvements at all. It still studders under load, when you need to give it gas. It only drives normal when creeping along very slow. I still have a new O2 sensor to install but I'm afraid it won't help as I think this problem is bigger than that. I am still going to try and put the new 02 sensor on anyway but so far my last ditch attempt to throw parts at the TBI is not helping.

I'm having an over-fueling problem myself. I'm running a JET Performance chip, the 2nd one theyv'e sent me, and they're claiming it's the correct one for GM's last ECM update for the TBI trucks. Everything but the TPS is new, I've rebuilt the TB, have a Power Tower, pod spacer, increased fuel pressure spring kit, TB bore casting clean-up, etc...

WFarm · Saturday at 7:34 PM

Taking advantage of the nasty weather and continuing detailing the underside.

Back in 2015/2016 the company I worked for had an open house for nuclear utility bigwigs to tour our shop and we had these hats made up and handed out. They were snatched up!

You must be registered for see images attach

Tank6x2 · 2025-01-19T01:08:47-0500

Cleaned up & organized today, then sat back - maybe tomorrow

Bowtie-dad · 2025-01-19T01:28:59-0500

I just did that. Along with a good time up using 500 ohm per foot 10 mm wires ceramic boots and pulstar fine wire plugs. Spendy upgrade but definitely worth it

Sgt Gus · 2025-01-19T11:22:14-0500

Mr Clean said:
OK... no big deal just thought I'd offer. I don't know enough about TBI to know if they are interchangeable or not. @Redfish just said something about changing the injectors, but like i said I don't know enough about TBI to know.

We will keep you in mind for parts!
220 TBI = 50mm and about 640 cfm, BB injectors more flow.

holyroller · 2025-01-19T17:14:35-0500

ChuckN said:
Good info. @JamesSam I’ll bow out now, since the TBI system is nothing I’m familiar with. The only other thing I can think of is checking fuel pressure. Sounds like @Ajax19 has a good handle on it.

I had this problem with idling and response in my 88 tbi, tech guy recommended dropping the fuel tank and replacing fuel pump and sending unit....fixed my issue... good luck.

bucket · 2025-01-19T17:45:06-0500

holyroller said:
I had this problem with idling and response in my 88 tbi, tech guy recommended dropping the fuel tank and replacing fuel pump and sending unit....fixed my issue... good luck.

I agree, it is definitely the usual symptoms of a weak fuel pump.

What have you done to your square lately??

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