I am trying to open this can of worms and maybe help others while be helped my self(possibly).
The message written below has been copied from another post I messed up titled shouldn't there be fuel pressure.

Sorry it took so long.




The Blazer I have been working on for the last 2 years is a 88 s-10.It was drug off the side of a hill for parts for my 91.
In my garage sat a 92 4.3 vortec begging for my attention.
Again I never intended to do anything with it other than sell it or part it out.
I had heard terrible things about the CPFI system and everyone wanted the 88 fixed up...have no idea why.
My idea was to install a TBFI system on a W engine.The best of both worlds.Smooth running engine with a bullet proof fuel system ,like my 91.
So I rebuilt the engine and did just that.
Note:this was my first rebuild.
It ran great but would fall on it's face at 1600 rpm's.Here in WV that can be dangerous.
Remember everything from front to rear is NEW.PC and pump included.
After checking everything dozens of times I finally decided that the cam and heads were just to much for the TBFI system .
After careful consideration and hundreds of dollars later I installed the dreaded CPFI.I figured I have a 95 with the TBFI on it but it is very ill,so maybe just use those parts on it after I removed them (TBFI).
Now when installing a CPFI system in an older s-10 you have to start at the rear.You gotta change the fuel pump and sending unit.Got Delphi stuff from Rock Auto along with all the other parts including AC Delco fuel injectors and gaskets.
You have to make NEW fuel lines and change the wiring harness under the hood.Best to do that after removing the manifold and distributor.
Thank GOD my wife and daughter have small hands and enjoy working on the on vehicles.
While under the hood you have to change the throttle cable,kick down cable and cruise control cable because the TBFI cables are about 4 inches to short.This is where some confusion has been about the cable.
Someone misplaced my throttle cable from the 92 CPFI.
The only thing I had was one from a 99 sonoma.
It works but the end that goes into the throttle bracket is different and must be secured some how.I just zip ties.
At this time I still have not changed the kick down cable on the transmission due to the fact I have trouble working over my head.
Heck took me 2 days just hooking up the Y pipe.
So the only cable hooked up is the throttle cable.
I also replaced most of the sensors on the engine.
While having the trouble listed above with high idle (720 when engine about 200 degrees)I aquired a code 23...IAT sensor.Also checked the TPS to find a reading of 0.42 while throttle closed-4.84 wide open.Went ahead and replaced it while at it.It runs better but still having the shifting and high idle bang problems.
Ok back to the install.We had to install the original 92 Digital dash and wiring harness to get it to run (during the install).We could have used the older dash but would have been a lot more trouble plus other were staring at the digital cluster like a deer getting ready to jump in front of you.
Once all was installed we had to run the newer fuel pump wires back to rear and splice them.(purple and grey) older ones are (red and grey.)

There is probably a lot more that I have not included but am willing to answer any questions if possible.

What I need help with is ...the cold shifting bang and clang.Seems to me it should not be affected by the kick down cable be unhooked.Correct?
Also why is it idling high.I have checked the time,plugged the vacuum, and disconnected the throttle cable.I also checked it for gasket leaks.
The transmission shifted and worked great before installing the CPFI unit.
Could it be the PC chip?
Any help would be appreciated.
Again.....if I insulted anyone I didn't mean to.
Hope you enjoyed my short book.

After calming down and thinking it over I realized...yes dummy you do need the tv cable hooked up.I have done the adjustment on the older metal linkage type many times before.Heck I would pull over and adjust them along side the road to get the shift points just right.I embarrassed my family but didn't tear up any transmissions.
We made a weak attempt to change the blazers tv cable but did not do to well.
So I decided to make a bracket and extend the tv cable by splicing another one into the existing TBFI tv cable.The bracket came from an older 4. 2wd I think.Had to grind the corners a bit but it does work.I still have some adjusting to do.

 

wow.. this is pretty awesome.. but do you have access to an FSM, or are you just really mechanicly inclined?

 

Thank you for your compliment.
The truth is I don't know what FSM means.Sorry.
I am just teaching myself as I go and hoping that there others out there who will help out with there knowledge.
So far I have been fortunate but there are some people who are....well not to nice and will tell you something to see you tear your equipment up.
Heck I can do that very well myself without help.

Here is an example:yesterday we took the blazer on a small trip.
It wanted to shift hard.Stopped 6 times and adjusted the tv cable in 1/4 inch increments.Finally got it to shift like my 91 s10.
Though it seemed to be a dog on the steep hills after pushing the skinny pedal a little harder it was down shifting great.We were smelling gasoline at the back end.
I immediately started to freak.Once I calmed down I did the most important thing I could....Please dear LORD bless us and this clunker.
We got home without any problems.
The tank was hissing on top but we can find any leak.
Like shaking a soda bottle and releasing the cap slowly.
I am thinking I checked the vacuum but did not get any on the bottom of the throttle body.My theory is that maybe the throttle body is not sucking the vapor and it is releasing through the relief on the tank.
I am scanning the internet and this forum for help and information.
My books don't have this kind of info.
So basically I have to learn through GOD,the kindness of others and my own many, many, costly mistakes.

 

That TV cable you have unhooked is the first thing anyone will tell you to look at for 'hard shifts'.. on any car, not just a blazer. That's what it's for. It modulates front pump pressures.
It must be adjusted so that just the tiniest bit of slack exists when the throttle is closed.
Also the full range of travel on that cable needs to be the same as it was on the old TBI

 

Yeah you are correct. After hooking it back up I found out how sensitive it really is. Just another example of being tired and even more simple than usual because of it.

 

FSM is Full Service Manual. do you have any kind of manual or tech data?
I want to start tearing apart an replacing my rear end.. but not certain where to start...

but keep up the good work, and post pics of your work

 

Purge valve and vent valves. If pressure is released when you remove the filler cap, vent valve is plugged.. common. Remember it's closed when actuated. open with no power.

 

That a good idea releasing the cap.
I have been busy with other chores and today is SUNDAY so maybe I will check it out tomorrow depending on the weather.
Been having storms here the last few days.

 

Howdy all. Messed with the Blazer today to find that a vacuum line that goes from the charcoal canister to the rear of the manifold was hooked into one going into the cab through the wiring harness. I cant remember what it is for but all is working including the heat selector. Also found that I get all kind of vacuum from the throttle body when I accelerate...around 19 1/2 .I think that is good. Now my question is whether or not should get vacuum from the vacuum side of the canister to the fuel tank side or not.Right now I don't. I do know that the line going to the tank appears to be clear. NoDakBlazer : Sorry I didn't get back to you sooner. I do not have a lot of experience with rear differentials but more than others. Depending on what you want to do. I have a 91 s10 4x4 that was my first victim 4 1/2 years ago. I took a blazer rear end and installed a rear disk brake system off of a 1983 pontiac firebird.I was scared to death I was gunna mess something up. I wanted to replace the bearing and seals but the guy I was working with talked me out of it.H swore he was a certified GM mechanic before he got hurt but found out he worked at a GM dealership as a body man but smoking dope was more important I guess.I did replace the seals. I should have swapped the springs too but again was duped. After all was said and done I still have it with over 12,000 mile of towing on it. I did start hearing the bearing lightly growling after I took the rough treaded tires off.So it is due after the blazer is fully functional. I guess it was pretty straight forward. I do have some information.Let me know what you need and I WILL try to help.

 

The blue blazer is the one we have been working on.
More or less started left to right.
Now the engine has the original vortec cpfi on it.