Why won't my TBI 350 run right??

[JoeR Jr]

THE MAIN PROBLEM, whether this is related or not or simply having to do with the throttle, when i'm giving it gas, there's nothing, there's nothing, then all the sudden there's everything!

Last one I had that acted like that was because the port for the MAP sensor was plugged with carbon. You'd hit the gas but the MAP sensor had a real bad time delay beofre it saw the vacuum drop. As a result it didn't add the fuel it needed to for proper enrichment.
It's fast and free to check that. See if you have good vacuum to the MAP sensor. It should be plumbed to manifold vacuum.
Joe

 

[SirRobyn0]

Last one I had that acted like that was because the port for the MAP sensor was plugged with carbon. You'd hit the gas but the MAP sensor had a real bad time delay beofre it saw the vacuum drop. As a result it didn't add the fuel it needed to for proper enrichment.
It's fast and free to check that. See if you have good vacuum to the MAP sensor. It should be plumbed to manifold vacuum.
Joe

Additionally, if you had a ALDL scanner in your back pocket you'd be able to see that by monitoring the MAP sensor data, you'd see the delay in vac drop, but you could also plumb your vac gauge into the line for the MAP sensor and you should see a delay in the vacuum dropping when you open the throttle.

 

[Rusty Nail]

Sweet video dood!

 

[AyWoSch Motors]

Here's the video/audio requested. Thanks for all of the ideas above, all will be looked into. And yes, as featured the fuel sprayers are working. Below are also the spark plugs taken out, bottom side is front of block and the left side will be the passenger side. And a flippin belt squeal just started now to add to the mayhem! The "vacuum" sounding leak i believe are the fuel sprayers, as i've determined. The idle does smooth out for a moment before i go under it, that's pretty much the best it does. i'm sure this is all timing related and throttle pedal related, not too experienced in timing so if you feel you must break it down into elementary terms, feel free

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I'd have to agree with a lot of people here, definitely sounds like either timing or the computer not reading something right.
That vacuum sound is perfectly normal for a TBI. Everyone I've ever heard sounds like that.
First thing I'd do, is time it.
I know on a 90s chevy, that plug is under the passenger side dash, by the heater box. On a Square, not a clue.
The way the thing works, is the computer trys to time it while it's running, and you can adjust it, but it won't set correctly.
You unplug that, time it as you usually would, set it at 0, then plug it back in, and the computer will reset it to whatever advance it desires. That'd be my first guess.
That happened to my Yukon. No matter how much I tinkered with it, couldn't get it right, until a friend told me about that.
After I unplugged that thing, it almost stopped running it was so far out of time, I couldn't see the line.
Now it runs perfectly.

Could be a MAP sensor, but you said you replaced it, so probably not.
The injectors are easy to take out and clean to scratch that off.
And I've heard you can read the old OBD1 plugs without a scanner. I think you use a test light or something.
Someone told me that years ago, dont have a clue if its right or not.
A scanner is pretty cheap to get, and they come in handy for a lot of things.

You could always get rid of all that TBI and computer nonsense. Just put an old style 4 barrel intake and a new carb, and itll go forever.

 

[SirRobyn0]

That vacuum sound is perfectly normal for a TBI. Everyone I've ever heard sounds like that.

And I've heard you can read the old OBD1 plugs without a scanner. I think you use a test light or something.
Someone told me that years ago, dont have a clue if its right or not.
A scanner is pretty cheap to get, and they come in handy for a lot of things.

Sorry I cut your post up but I really only want to comment on one thing since none the rest of us have said anything so far. But first thank you for say that sound is normal, I'm the only other person who has said that.

You can flash codes, and you can get the check engine light to flash real time information about what the O2 sensor is reading, none of which will help the OP unless he runs the thing long enough to set a code. But to flash codes you cross the two upper right terminals with a paper clip, then turn the key on, it'll flash long flashes and short flashes the long flashes are the first digit the short flashes are the second digit. It'll flash a code 12 which is the only normal code. He'd want the scanner to look at live data to see if sensor are working and what the computer is doing with the advance.

 

[AyWoSch Motors]

Sorry I cut your post up but I really only want to comment on one thing since none the rest of us have said anything so far. But first thank you for say that sound is normal, I'm the only other person who has said that.

You can flash codes, and you can get the check engine light to flash real time information about what the O2 sensor is reading, none of which will help the OP unless he runs the thing long enough to set a code. But to flash codes you cross the two upper right terminals with a paper clip, then turn the key on, it'll flash long flashes and short flashes the long flashes are the first digit the short flashes are the second digit. It'll flash a code 12 which is the only normal code. He'd want the scanner to look at live data to see if sensor are working and what the computer is doing with the advance.

Yes yes, forgot about that trick with the paper clip. That works, I did that on my jeep, with an OBD2. Just watch the engine light flash.
Did that on a buddies Nissan too, but on his, you stick a pin in the ECU, and watch the light on the side, and count the flashes.
You can read the Err codes in your Haynes/Chilton if you have one.

 

[Powerhouse Ranch]

I'd have to agree with a lot of people here, definitely sounds like either timing or the computer not reading something right.
That vacuum sound is perfectly normal for a TBI. Everyone I've ever heard sounds like that.
First thing I'd do, is time it.
I know on a 90s chevy, that plug is under the passenger side dash, by the heater box. On a Square, not a clue.
The way the thing works, is the computer trys to time it while it's running, and you can adjust it, but it won't set correctly.
You unplug that, time it as you usually would, set it at 0, then plug it back in, and the computer will reset it to whatever advance it desires. That'd be my first guess.
That happened to my Yukon. No matter how much I tinkered with it, couldn't get it right, until a friend told me about that.
After I unplugged that thing, it almost stopped running it was so far out of time, I couldn't see the line.
Now it runs perfectly.

Could be a MAP sensor, but you said you replaced it, so probably not.
The injectors are easy to take out and clean to scratch that off.
And I've heard you can read the old OBD1 plugs without a scanner. I think you use a test light or something.
Someone told me that years ago, dont have a clue if its right or not.
A scanner is pretty cheap to get, and they come in handy for a lot of things.

You could always get rid of all that TBI and computer nonsense. Just put an old style 4 barrel intake and a new carb, and itll go forever.

thanks again Ayden, do you know where i could find out where this plug is at? alot of people are telling me to disconnect the thing for timing

 

[Powerhouse Ranch]

Yes yes, forgot about that trick with the paper clip. That works, I did that on my jeep, with an OBD2. Just watch the engine light flash.
Did that on a buddies Nissan too, but on his, you stick a pin in the ECU, and watch the light on the side, and count the flashes.
You can read the Err codes in your Haynes/Chilton if you have one.

i think another Square enthusiast in my household has stolen my Haynes. . .

 

[AyWoSch Motors]

thanks again Ayden, do you know where i could find out where this plug is at? alot of people are telling me to disconnect the thing for timing

I'm unfamiliar with squarebodys with TBI, but I can look tomorrow. My boss had an 87 with TBI. I'm sure someone here knows better than I.

i think another Square enthusiast in my household has stolen my Haynes. . .

Haha, have had that happen before.
I have one, I can look them up for you.

 

[Rusty Nail]

Are yall talkin about the brown wire / plug?
I think it's curious that nobody knows how to disconnect that spout connector but they all got squares and are telling each other how to fix theirs. But they dont really know.
Pretty great thread u got goin here old boy.

I think "spout connector" is a Ford term but same difference here. Good luck!

P.S. it sounds like the IAC motor needs adjustment to me. Turn it up a little bit?


Brown wire / black stripe on the firewall underhood.

 

[gmbellew]

the wire to disconnect when setting timing to 0 comes out of the harness off the firewall by the brake master cylinder. brown wire with a black stripe I think with a single wire plug. ideally, the timing is set with a fully warmed up engine. unplug the connector after starting the engine and letting it warm up. set timing to 0. turn off engine. plug the connector back in. disconnect negative battery cable for a couple minutes to clear codes. reconnect battery cable and start it up.

 

[SirRobyn0]

Are yall talkin about the brown wire / plug?
I think it's curious that nobody knows how to disconnect that spout connector but they all got squares and are telling each other how to fix theirs. But they dont really know.
Pretty great thread u got goin here old boy.

I think "spout connector" is a Ford term but same difference here. Good luck!

P.S. it sounds like the IAC motor needs adjustment to me. Turn it up a little bit?


Brown wire / black stripe on the firewall underhood.

Well in my case I've worked on lots of GM TBI motors, but I've never owned one. When was the last time I timed one? Probably a year or more ago, but I don't feel I remember well enough where that wire is exactly and the color and don't want to send him off to look in the wrong spot. I'm sure the OP can google if none of us can reliably give the location.

The ALDL connector should be just to the right or left of the steering column. But again I don't have one in front of me to check exactly where it's at.

 

[SirRobyn0]

@Powerhouse Ranch Curious if you have made any progress with this issue?

 

[Powerhouse Ranch]

@Powerhouse Ranch Curious if you have made any progress with this issue?

hey thanks for checking in pal!

It so happens i'm shoulder deep in the 1980 GMC C25 (my daily, well sunny day summer/fall daily) due to practically no rear brakes, leaking rear pinion seal, leaking output shaft seal on the tranny and fix my speedo gear. My odo or speedo haven't worked for over a year now. The rear seal starting leaking pretty good and after trying a few panic stops and my rear brakes almost causing me to total my truck, i decided it was time to do these chores for the old girl.

UPDATE ON THAT SO FAR:

Got the rear brakes sorted out; one cylinder was leaking and the other seized. Been like that for AWHILE. Longer than i wish to admit. I just pulled the rear yoke today, replaced the seal and reinstalled the yoke, best of my abilities with the notching method (anyone know correct yoke nut torque for 14-bolt, just to be sure?). Moved up to the tranny, pulled that yoke and then the rear housing cover. This has been taking weeks though to do, between finding the right parts, the right tools and actually having the time. It has been frustrating. I now have to find a rear tranny seal and the gasket for that rear housing. That's going to be fun.

OH YEAH. and i forgot to notch the tranny yoke, was too gung-ho to get it off. Anyone know the rear output shaft yoke nut torque on a Muncie SM465?

But yeah, the '88 sits patiently as its sister gets fixed, waiting for it's date with the timing light. All in due time. . .

 

[SirRobyn0]

@Powerhouse Ranch couple things I can really sympathize with you on. "actually having the time. It has been frustrating." Ya, I can really understand that. My fuel gauge took a crap two weeks ago, it's the gauge. I want to fix a few other things while I'm in there. some burned out bulbs, lube the speedocable ect. Well now it has to wait at least 3 weekends. I had some time the weekend before this one, but this one and the next to are wall to wall booked with farm stuff. Such as life. gotta wait.