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350 Wont Idle/Will Idle Too High/ Wont Idle You get The Idea- SOLVED:)

I bought the gears buddy but then the local mechanic said he cant do the job:haha:It gets better. I was getting supplies for my camper at grocery store in Man,WV and one of the clerks saw me drive up in the K5. He said he has some 3/4 ton axles from an early 80's truck that he's been keeping in his garage for 7yrs. He claims that they have 4.11 gears and will let me have them both for $50.00. Can you believe that? $50.00! I dont have a pickup here but I will try and get those axles from him after first inspecting and verify gears.

Fordum said:
Sounds like you got a handle on it. Just out of curiosity, how is the gear swap going?
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Ok cool. I only work on family vehicles and they are all FI imports.

4X4HIGH said:
If you work on any other cars I would suggest you buy the whole kit not just the single one for TBI. You can buy the whole kit for $40.00 from just about anywhere.
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Guys
I got the backup TBI unit @ 6PM and rebuilt it. I just finished swapping it in and same results. Every sensor on that unit is new as well as O2. Same code 45 and irratic idle/no idle. This brings me back to the PROM, its the only 21 year old part in the equation. Why are the injectors dumping more fuel.
 
You said you replaced all the sensors so I wont go there.Did you check the wiring and for the proper ref voltages etc to the sensors?Fuel dumping could be simply a wiring or conection problem with the coolant temp sensor that sends a signal to the computer.Not the guage send unit the one for the computer.I would expect a rich code if its dumping so check all related compenents that control that.
 
I can datalog with WinALDL and the ECM is recieving the right Temp. The sensors are new, the timing is at 0 and I just put on a rebulit TBI. I thought about the brake booster, so I unplugged it and plugged the hose same issue. I've checked for vaccum leaks and found none. I've tested the EGR and it checked out. I am getting the rich code 45 every time.

zombie1969 said:
You said you replaced all the sensors so I wont go there.Did you check the wiring and for the proper ref voltages etc to the sensors?Fuel dumping could be simply a wiring or conection problem with the coolant temp sensor that sends a signal to the computer.Not the guage send unit the one for the computer.I would expect a rich code if its dumping so check all related compenents that control that.
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Man, that sucks, I thought you had it.
Have you tried the unplugging trick again?
I hate to bring it back up, because I really thought you had found the trouble when the unplugging showed a problem, but now I'm going to toss the fuel pressure back out there.
It sucks that there is not a port you can measure it without having to buy something.

BTW, I would ask around here, but if those axles are GM 3/4 tons in good shape, I suspect that the price is worth it no matter what gears are in them.
If you can't use them, someone else here probably can.
For repair parts if nothing else.

And, while 4.11s will definitely help your situation, I still like the ones you bought. Did the guy say why he could not put them in?
 
Just to continue to be the bearer of good thoughts, I wonder if it could be the fuel pump.

I am 9/10s convinced that it is a fuel problem.

Its one or the other. Either the computer giving the wrong commands, or it has lost control of the fuel flow.

If the computer is not bad, then it is expecting the same amount of fuel per millisecond of open of the injectors.

I have been concentrating on the regulator since that is the usual thing that determines the pressure.
But what if the pump is acting up?

Either the pump part is coming loose from the motor and sometimes slips and sometimes grabs and pumps good, or there is something blocking the intake from time to time, or as someone else posted, the hose is loose inside the tank.

About the only way to find that, other than pulling the pump, is the pressure gauge, or, maybe, after cranking the engine, taking the gas cap off and listening to the pump.
If you can hear it over the engine.

If it sounds like it is changing tone, and especially if that change is followed by an engine change, you Might have found the problem.
 
I drive home and decided to replace every sensor on the truck. I got new TPS, EGR Vacuum Selenoid, MAP, Distributor, IAC, O2, cap and rotor button and rebuilt the TBI. In the morning I will finish up and see what happens.

I made a mark on the firewall when I pulled the distributor now I cant get it to line up again. I wonder if the rotor button has to be in the exact spot when you pull the distributor.

Fordum said:
Just to continue to be the bearer of good thoughts, I wonder if it could be the fuel pump.

I am 9/10s convinced that it is a fuel problem.

Its one or the other. Either the computer giving the wrong commands, or it has lost control of the fuel flow.

If the computer is not bad, then it is expecting the same amount of fuel per millisecond of open of the injectors.

I have been concentrating on the regulator since that is the usual thing that determines the pressure.
But what if the pump is acting up?

Either the pump part is coming loose from the motor and sometimes slips and sometimes grabs and pumps good, or there is something blocking the intake from time to time, or as someone else posted, the hose is loose inside the tank.

About the only way to find that, other than pulling the pump, is the pressure gauge, or, maybe, after cranking the engine, taking the gas cap off and listening to the pump.
If you can hear it over the engine.

If it sounds like it is changing tone, and especially if that change is followed by an engine change, you Might have found the problem.
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Ok. I changed all sensors and still got same issue. I got another ECM/PROM and that solved nothing but it did put my bad PROM thoery to rest. I'm gonna pull the fuel pump now.
 
Did you see the post about the inside the tank fuel hose?
I don't remember who posted it, but someone here had weird fuel problems, and found a hole in the short piece between the pump and the output connection inside the tank.

But I don't remember the symptoms.

I'm still sticking with fuel flow problems, but other than that hose, I'm not sure how the pump would cause the problem.
I liked the idea of a bad connection between the motor and pump that let it slip and then grab, but I would have thought that it should have gone ahead and worn out by now.

I wish I knew a little more about the flow system of a GM TBI
 
Just pulled the tank now i need to figure how to remove the fuel pump.
Also, while changing the TBI gaskets again and the the truck off, I had fuel flowing tru the line. I dont know why but it flowed unto the intake about three times before stopping.



Fordum said:
Did you see the post about the inside the tank fuel hose?
I don't remember who posted it, but someone here had weird fuel problems, and found a hole in the short piece between the pump and the output connection inside the tank.

But I don't remember the symptoms.

I'm still sticking with fuel flow problems, but other than that hose, I'm not sure how the pump would cause the problem.
I liked the idea of a bad connection between the motor and pump that let it slip and then grab, but I would have thought that it should have gone ahead and worn out by now.

I wish I knew a little more about the flow system of a GM TBI
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These are pics of the new fuel pump. I didnt find any hoses in the tank or was there any hoses attached to the pump assembly

100_1453.JPG

100_1454.JPG
 
I think I mistyped.
I'm pretty sure he was talking about that little short piece of hose between the pump its self and the tube going up to the outside of the tank.
Its more of a flexible coupling than a hose, but I'm pretty sure that is the part that had the hole in it.

How does that "sock" filter on the bottom of the old pump look?
 
it looks ok.

Fordum said:
I think I mistyped.
I'm pretty sure he was talking about that little short piece of hose between the pump its self and the tube going up to the outside of the tank.
Its more of a flexible coupling than a hose, but I'm pretty sure that is the part that had the hole in it.

How does that "sock" filter on the bottom of the old pump look?
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I may have solved the problem but I'll have to wait until Tuesday to know for sure. After replacing every sensor on the truck including the fuel pump it still ran like crap. So by deduction I turned to the intake manifold. I recalled another boardee suggesting that vacuum leaks could occur below the intake.

I pulled it and I was surprised at how loose some the bolts were especially in the back of the block. I found no carbon build up in the EGR port or in the heads. I replaced the gaskets and was finishing up the job when I broke the fuel inlet port on th TBI unit. Now I'm forced to wait until the backup arrives on Tuesday.
 
Well with all that I've done I still have this rough idle and rich condition. Now I'll look at the brake booster closer. I cannot detect any leaks but I will try replacing that valve on the booster.

On another note, should there be a vacuum when I pull the hose off the EGR valve. I dont feel a vacuum when I pull that hose off.
 
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Man, your equipment really bugs me.......
Hmm, you know, on second thought, that does not sound right at all.

Let me rephrase that.
It ticks me off that your truck does not respond to normal fixes.
Yeah, thats better.

Anyway, while I still like the idea of fuel, you have pretty much eliminated that idea, and vacuum leaks supposedly will cause the same problem, so hopefully you are on the right track.

Again, I'm out of my depth, since I know Fords a lot better than GMs, but on my truck the EGR control vacuum is controlled by the computer.
It only supplies vacuum to the EGR valve under certain circumstances. And I'm pretty sure that idle is not one of them.

If you open the EGR valve at idle, it usually kills the engine.

PCV line, on the other hand, should have good vacuum at idle.

Whatever it is, its probably going to look obvious when you find it.

I got my old 1966 3 ton boom truck and it would not idle worth a darn.
So, I replaced the water pump, as long as I was under the hood, the fuel pump, and put on a rebuilt carb.
Better, but still not great.

It did not have power brakes, so I did not worry about that. Just a master cylinder on the firewall.
While bleeding the brakes, and looking for the leak that let it run out, I found this huge object mounted on the frame under the drivers side.


The brake line ran into and out of it.
Put a light on it, scraped about 40 years of dirt and grease off, and discovered it was a remote vacuum operated brake booster!
With a busted diaphragm.

Put on a rebuilt, got great brakes and a great idle.
So, you never know.
 
Man
I dont own a gun but if I did I would shoot this truck in its heart! I'm exhausted and fedup. I'm still out to work in WV so I'm having to do all this work with minimum tools etc. I pulled the intake back off last nite and removed the EGR valve. I inspected and tested the diaphram for free movement and was able to blow through it. It looked good. I replaced the intake and reset the timing etc. I changed the TBI gaskets again (even doubled them) and fired her up, same idle issue. I sprayed the intake with carb cleaner while she rough idled in the hopes of finding a leak but found none.

I did change out the check valve on the brake booster but it solved nothing. I'm wondering if the inproper valve adjustment can cause my problem. I'm considering going to a carb, this computer **** is pissing me off.

Fordum said:
Man, your equipment really bugs me.......
Hmm, you know, on second thought, that does not sound right at all.

Let me rephrase that.
It ticks me off that your truck does not respond to normal fixes.
Yeah, thats better.

Anyway, while I still like the idea of fuel, you have pretty much eliminated that idea, and vacuum leaks supposedly will cause the same problem, so hopefully you are on the right track.

Again, I'm out of my depth, since I know Fords a lot better than GMs, but on my truck the EGR control vacuum is controlled by the computer.
It only supplies vacuum to the EGR valve under certain circumstances. And I'm pretty sure that idle is not one of them.

If you open the EGR valve at idle, it usually kills the engine.

PCV line, on the other hand, should have good vacuum at idle.

Whatever it is, its probably going to look obvious when you find it.

I got my old 1966 3 ton boom truck and it would not idle worth a darn.
So, I replaced the water pump, as long as I was under the hood, the fuel pump, and put on a rebuilt carb.
Better, but still not great.

It did not have power brakes, so I did not worry about that. Just a master cylinder on the firewall.
While bleeding the brakes, and looking for the leak that let it run out, I found this huge object mounted on the frame under the drivers side.


The brake line ran into and out of it.
Put a light on it, scraped about 40 years of dirt and grease off, and discovered it was a remote vacuum operated brake booster!
With a busted diaphragm.

Put on a rebuilt, got great brakes and a great idle.
So, you never know.
Click to expand...
 
I don't think valves would do it. If they were set too tight, it might start off running OK, but then start getting rough when the engine warmed up and the valves started not closing all the way.
But whatever happened, it should not change from minute to minute like yours does.

Looking at it logically, for the engine to speed up, the mix has to get richer.
If you had a vacuum leak that came and went, the computer would be pumping in more fuel when it was leaking to overcome a lean condition, and that would be too rich when the vacuum leak stopped.

I don't think you have a vacuum leak, since nothing happened when you sprayed the cleaner.

Have you done anything to the IAC? Idle control valve? You have done so much, its hard to keep track.

Here is an interesting link.
http://www.gmcmidwestclassics.org/Web pages/Web pages-09/Tuning the TBI.pdf

It talks about adjusting the idle, and mentions adjusting the little screw that holds the throttle open.
I doubt that you have the equipment where you are to do the kind of testing they talk about, but you might check to see what the idle is with the IAC closed.
The computer can only close it all the way. If it idles too fast then, the computer would get confused.

Also, what happens when you unplug the injectors now? I know you rebuilt them, but I'm wondering if there is something worn out that you cannot see.
 
The IAC is new. As I said earlier, every sensor in cluding the fuel pump is a week old. Now I did notice that the IAC area smokes when the truck dies after rough idling for a while. I will try changing the IAC again and see what develops. I will have to wait until tomorrow to try that.

Fordum said:
I don't think valves would do it. If they were set too tight, it might start off running OK, but then start getting rough when the engine warmed up and the valves started not closing all the way.
But whatever happened, it should not change from minute to minute like yours does.

Looking at it logically, for the engine to speed up, the mix has to get richer.
If you had a vacuum leak that came and went, the computer would be pumping in more fuel when it was leaking to overcome a lean condition, and that would be too rich when the vacuum leak stopped.

I don't think you have a vacuum leak, since nothing happened when you sprayed the cleaner.

Have you done anything to the IAC? Idle control valve? You have done so much, its hard to keep track.

Here is an interesting link.
http://www.gmcmidwestclassics.org/Web pages/Web pages-09/Tuning the TBI.pdf

It talks about adjusting the idle, and mentions adjusting the little screw that holds the throttle open.
I doubt that you have the equipment where you are to do the kind of testing they talk about, but you might check to see what the idle is with the IAC closed.
The computer can only close it all the way. If it idles too fast then, the computer would get confused.

Also, what happens when you unplug the injectors now? I know you rebuilt them, but I'm wondering if there is something worn out that you cannot see.
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