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Discussion Starter · #1 ·
Hello Forum!
First post here, the important data first

1990 Geo Tracker USA 1.6 liter MT TBI

My throttle body is cracked at the bottom, where the injector sits, fuel is dripping into the intake and making a mess of plugs and O2 sensor, runs badly of course. I can't find a 1990 throttle body with the idle control valve used in that year (cylinder shaped, different resistance from 1991 and up ), the idle valve was not connected and the passages filled with RTV, it ran sort of OK like this, before the TB cracked.

I was wondering if I could install a throttle body from a 91, I will probably not be able to use the idle valve from that year, but I could make it run by adjusting the screw where the throttle plate sits ( yes the one you are not supposed to touch ) or maybe someone has a better idea.

Will the 90 ECU play ball with a 91 injector? I understand the 91 injector will not fit on a 1990 throttle body, or so I read at FixKick...

All suggestions are appreciated.
 

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Welcome to the forum. Try your search using Suzuki Sidekick instead of Geo Tracker. You are actually driving a rebadged Suzuki Sidekick. The 1989 and 1990 Sidekick engines will be the same as yours. Tracker, sadly, is no longer supported.
Have you tried junkyards, looking for the Suzuki Sidekick? The throttle bodies are different, although they do bolt on similarly, AFAIK, but the injector is different.
Did you look over in the classified area to see if someone was parting out an 89/90??
 

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In looking through some of the posts regarding people having difficulties such as yours, I come across Aquanaut’s post - he’s expert in welding. His recommendation, for someone with your problem, was to take your throttle body, made of aluminum, to a welding shop and have it TIG welded.
So, that may be an option.....
 

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Discussion Starter · #4 ·
In looking through some of the posts regarding people having difficulties such as yours, I come across Aquanaut’s post - he’s expert in welding. His recommendation, for someone with your problem, was to take your throttle body, made of aluminum, to a welding shop and have it TIG welded.
So, that may be an option.....
Thank you so much Bex, I was able to source an entire intake manifold from a 1990... I will take it apart, clean it, add new gaskets and put it back together, report my findings. And will probably stick around the forum since I have more fixes pending for the car, like the CEL light that refuses to go away no matter what I do.

Here's a picture of the throttle body crack
100857


Here's the little truck!

100858
 

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Nice car and color!
Might be too late, but run a fingernail over that "crack", if you find that it is a tiny raised ridge, then it is not a crack in the aluminum. Im saying this because it is a very odd location, a non stressed area for a crack to develop. also, a stress crack would run from the hole itself into the part and have dirty deposits inside.

Many people see these marks and think they are cracks, but most times they are not....part is just fine.
The root cause of these "crack-like" markings in casting is surface deterioration of the tool-steel casting die (the mold) that is used to cast the part. Thousands of thermal shock cycles (expansion & contraction) from contact with molten aluminum at over 1,000 degrees F cause a thin layer on the surface of the die to eventually "fatigue", and tiny superficial cracks form.

The correct metallurgical name for this deterioration of the die is "heat-checking".

Here's a photo from the web showing the surface of a badly heat-checked casting die:

 

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Discussion Starter · #6 ·
Nice car and color!
Might be too late, but run a fingernail over that "crack", if you find that it is a tiny raised ridge, then it is not a crack in the aluminum. Im saying this because it is a very odd location, a non stressed area for a crack to develop. also, a stress crack would run from the hole itself into the part and have dirty deposits inside.

Many people see these marks and think they are cracks, but most times they are not....part is just fine.
The root cause of these "crack-like" markings in casting is surface deterioration of the tool-steel casting die (the mold) that is used to cast the part. Thousands of thermal shock cycles (expansion & contraction) from contact with molten aluminum at over 1,000 degrees F cause a thin layer on the surface of the die to eventually "fatigue", and tiny superficial cracks form.

The correct metallurgical name for this deterioration of the die is "heat-checking".

Here's a photo from the web showing the surface of a badly heat-checked casting die:

Thank you sir! I pressurized the injector using an injector cleaning machine and found fluid coming thru the crack, so I know it's bad... Can't explain how it happened though...

Sent from my SM-N9600 using Tapatalk
 

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Glad that you were able to source another throttle body - they are like hen’s teeth. (And you may want to consider the TIG weld suggestion, so that you have a spare.....)
With regard to the check engine light....The check engine light serves 2 purposes - to show faults that the computer has picked up, and to ‘nag’ you to ‘service the engine soon’.
The nag switch usually kicks off at specific mileages, like 50,000, 70,000, 100,000, etc. In order to see if this is the nag switch, remove the panel that is just below the steering column, and stick your hand about 2-3 inches down. There will be a TINY switch that can be moved from left to right (or vice versa). Find that little switch and move it to the opposite side of where it currently is, in order to turn off the nag function.
If the computer has thrown a code, usually it’s a good idea to retrieve the code before resetting it. You can reset it by removing the dome light fuse for a minute. If you need info on how to retrieve codes, the info is here:
You are looking for a tiny white box with a black locking top, dangling off of 4 wires, just in front of the battery.
 

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thats a very odd crack indeed.... can you see it also from the inisde? beats me too as to why it'd appear there...
 

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Discussion Starter · #9 ·
Glad that you were able to source another throttle body - they are like hen’s teeth. (And you may want to consider the TIG weld suggestion, so that you have a spare.....)
With regard to the check engine light....The check engine light serves 2 purposes - to show faults that the computer has picked up, and to ‘nag’ you to ‘service the engine soon’.
The nag switch usually kicks off at specific mileages, like 50,000, 70,000, 100,000, etc. In order to see if this is the nag switch, remove the panel that is just below the steering column, and stick your hand about 2-3 inches down. There will be a TINY switch that can be moved from left to right (or vice versa). Find that little switch and move it to the opposite side of where it currently is, in order to turn off the nag function.
If the computer has thrown a code, usually it’s a good idea to retrieve the code before resetting it. You can reset it by removing the dome light fuse for a minute. If you need info on how to retrieve codes, the info is here:
You are looking for a tiny white box with a black locking top, dangling off of 4 wires, just in front of the battery.
I found it, and moved it as you said. What happens now is that the CEL light gives me a Code 12... keep in mind I did not insert the paper clips on the white box at the front of the battery ( perhaps this box is grounded?, the electrical system has been tampered with badly ) When I move it back, I get the CEL light on again. Would removing the dome fuse not be the same as disconnecting the battery overnight?

thats a very odd crack indeed.... can you see it also from the inisde? beats me too as to why it'd appear there...
All I can guess is that at some point someone dropped this part to the floor or hit it somehow, I can't really see the crack from the inside, but we saw the fuel coming out. I got the car from three young brothers, who wanted to restore it, they had to stop at the middle of the restoration because one brother has a baby on the way... 🤷‍♂️

I am not sure this will fix my problem, it may be the ECU, but I am not sure if the 1990 experiences the faulty capacitor problem... Also I understand the bad capacitors prevent your injector from firing, mine fires all right, just that the car is flooding... no matter what, the crack was a leak and had to be fixed, but I feel unsure about this fixing the entire problem... I will keep you posted and please keep the suggestions coming
 

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Code 12, of course, means that the computer sees no major faults. You seem to be saying that with the service engine soon function turned off, the CEL starts blinking. That would seem to indicate that the blue/yellow wire and black wire, as found in the little white box, are jumpered to each other, somewhere along that circuit.
Removing the dome light fuse just resets the computer. Disconnecting the battery would also interfere with your radio settings, etc.
All the cars from 1989-1995 have an issue/concern with the capacitors...and one of those capacitors is directly involved with fuel delivery. If you have the original caps still in your ECU, change them. If your engine is flooding, check your fuel pressure regulator - remove the vacuum hose (on the right of the FPR as you are standing in front of the car) and see if the hose is wet inside. If so, then you need to replace the FPR. Maybe checking the fuel pressure might also be a good idea.....
 

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Discussion Starter · #11 ·
Code 12, of course, means that the computer sees no major faults. You seem to be saying that with the service engine soon function turned off, the CEL starts blinking. That would seem to indicate that the blue/yellow wire and black wire, as found in the little white box, are jumpered to each other, somewhere along that circuit.
Removing the dome light fuse just resets the computer. Disconnecting the battery would also interfere with your radio settings, etc.
All the cars from 1989-1995 have an issue/concern with the capacitors...and one of those capacitors is directly involved with fuel delivery. If you have the original caps still in your ECU, change them. If your engine is flooding, check your fuel pressure regulator - remove the vacuum hose (on the right of the FPR as you are standing in front of the car) and see if the hose is wet inside. If so, then you need to replace the FPR. Maybe checking the fuel pressure might also be a good idea.....
I am going to order the caps today, tomorrow I will rebuild the throttle body... PO blocked the passages for the idle valve, not sure why, I tested the valve and it is working, also I had the injector cleaned and assembled at a shop to make sure I have no leaks... I will have to check the wiring for the little white box to find where it was grounded, not fun...

I do have a fuel pressure gauge, but the only way to check the fuel pressure is at the tank, so I don't know how to achieve this without removing it... all other lines are hard. The FPR checked ok, not wet so that's a relief...

Any suggestions on how to measure the fuel pressure without dropping the tank?

Thank you for all your help Bex, I can see this forum is a great place!
 

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FSM shows the fuel pressure as being tested at the input to the fuel filter, which should not require the tank to be dropped.
 

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Here for the 8v:
 

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Discussion Starter · #14 ·
FSM shows the fuel pressure as being tested at the input to the fuel filter, which should not require the tank to be dropped.
Thank you sir!! will try this

Here for the 8v:
Thank you so much sir, now I need an expert eye... here are pics of the ECU and caps, do you see any evident damage? which one of these affects the injector?

100885


100886


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100888


100889
 

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I see that your capacitors (C101, C103 and C111) are the original Rubycon caps, and should be changed. Often you don’t see any damage to the board until the caps are removed, and if they have dried out, there may be no damage to the board at all. You should replace them. The C111 cap is involved with the injection/fuel. Rhino gives more info here:
 
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Discussion Starter · #16 ·
I see that your capacitors (C101, C103 and C111) are the original Rubycon caps, and should be changed. Often you don’t see any damage to the board until the caps are removed, and if they have dried out, there may be no damage to the board at all. You should replace them. The C111 cap is involved with the injection/fuel. Rhino gives more info here:
I found the capacitors on a local store, I am not in the US so I have to do with what I can but I found them. I will replace them and clean the board and then post my results here.

Thank you so much Bex, and all of you, stay tuned for more pictures.
 

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Discussion Starter · #17 ·
Capacitors are toasty

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100895


100897


Here are new ones, there is one more I want to replace, will do tomorrow

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I tested all solder joints for continuity and everything checks out... I am hoping my CEL light will go away and the car will not flood anymore...

I am putting it back together tomorrow, will post an update afterwards
 

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yep, looks like old caps, well done on changing them, fingers crossed the issues go away.
 

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Discussion Starter · #19 ·
yep, looks like old caps, well done on changing them, fingers crossed the issues go away.
Thank you sir.

The repair was a great success. Car is purring like a kitten. However I was still not happy with the acceleration and decided to check my timing. My distributor vacuum advance is not working...

Is this a part you can purchase for a reasonable price or dealer only? I'm leaving a lot of power in the table without vacuum advance.

I want to thank all of you who participated in this thread... I was able to fix the car because of the shared knowledge and helpful attitude all of you displayed. Many many thanks!

Sent from my SM-N9600 using Tapatalk
 

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Just to confirm (despite the title of this thread) currently the vehicle is a 1990 Tracker, all stock, and nothing from any other vehicle, correct??
I believe that the distributor should hold vacuum for about 30 seconds, if the diaphragm is ok. It doesn’t??
 
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