# 94 chevy s10 4.3 v6 problems



## Co.45 (Aug 11, 2008)

I just recently bought a truck from a friendfor 500 has 113k on it and isnt rusted up bad. When i bought it he told me about the rear window acting up and that it stalls. I finally got driving in it and it basically stalled at red lights randomly so i got on here found info about cpi and egr so i decided to order the tomco clean screen figuring eventually it will need it if it isnt the problem now. i have an electric egr and i pulled it out and cleaned the plate that connects to the engine covering the port spraying it at an agle. got it cleaned and back in with the tomco. there was no difference
so i checked for vacum leaks and found a couple. fixed them and now its running worse? it would idle terrible before and stall while in gear but now in park it lops reving up and down for a four to five mins then stalls?

i also checked all the vac hoses i could see in the engine compartment and i did find three that go straight back and above the tranny. so i didnt get the other end of those to check for vacume but the ones in the comapartment are all working. the previous owner also said the problems occured 6 months ago during a distributor cap change (right beside the broken hose) and he was running it like this for a while. and the main hose that was all but split in half was coming form the engine to left of the cap.

im not sure what it could be, would this problem be casued by the cpi? 

and i while its runing it almost seems to run a little better if i unplug one of the vacum hoses on the backside of the engine. when you pull it, it whistles then it slows down and the engine sorta smoothes out and randomy revs up in down instead of a constant low and high idle then stall.

it is still drivable and jumps around a little bit during driving.

any help would be great


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## Raylo (Feb 12, 2006)

I have the exact same truck and motor. The surging makes it sound like you still have a vacuum leak. Do the HVAC controls work OK? The area behind the dist is a PITA. There is a major vacuum tap in the intake manifold on the passenger side of the dist that goes to a Y. One leg of the Y goes through the firewall to the HVAC inside the cab. That operates the dampers and temp controls. The other leg of the Y has a thin hard flex tube that goes over to the drivers side of the motor to a little round thingy that happens to be the evap purge valve. That thin hard tube opens the diaphragm in the purge valve. The purge valve has 2 other main connections that communicate when the thin hard line vacuum opens the diaphragm. One goes to a hard metal line on the rear of the drivers side head that goes to the evap canister and solenoid near the fuel tank. The other connection goes to a hard flex line that goes to vacuum tap just under the throttle body. It's easy to dislodge any or all of these while futzing with the dist. Plus some of the lines can be cracked with age. And don't forget to check the PCV line for cracks.

I've not heard of CPI causing surging but I guess it's possible. The upper plenum comes off pretty easily and you can look for "clean" areas near the incoming plastic fuel lines or the FPR for signs of leakage. Fuel can leak here and cause problems. You'll probably need a new plenum gasket... typically carried at the local parts places for $12-$15. Also, it is much easier to get at the vacuum lines back there with the upper plenum off.

Oh, when you cleaned the EGR I assume you also cleaned the pintle and seat in addition to the mating surface and ports. That is essential to get it to seat properly.


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## Co.45 (Aug 11, 2008)

Yeah the bi level controls were out and when we fixed the bad lines they came back so.


behind beside the cap
1. this goes to cabin 2 was splitt in half and 4 was bad and if im right 5 goes over to the weird thing but it has good suction and didnt see any leaks

near battery

1 was also bad but has very little suction and runs back above the tranny
didnt yank the battery and stuff out to see where 2 goes to check that whole line either

and the pcv valve looked good the hoses had to be replaced

and earlier i was driving and it stalled while turning.

i took alot of time cleaning the EGR but the vavle pushes in so it was hard to clean anything below thr vavle but i did get everything around it and clean the block a little it was hard to reach since i cheated and just squeezed my hand in there. 

would a bad egr cause this cuz my book mentioned a leaking erg as a cause of irregular idle speeds? i was worried cuz i was told by three different people spray will mess with the diaphram?


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## Raylo (Feb 12, 2006)

I don't think a little but of cleaner will kill the EGR. As long as the plunger returns and seats when you push it it is prob OK. But if you really flooded the EGR with cleaner I guess it's possible to have damaged it. You could try to replace it but these are pretty $$ for a guess.

The vac line under the battery is part of the 4x4 shift mechanism. The actuator is under the battery and operates a cable that goes to the xfer case.

One thing you should do is put a vacuum gage on it and see what vac is. A convenient point to check is at the little black ball on the drivers side of the hood. That is the vac reservoir and the line on the back comes off easily and you can plug that line into your gage. My vac runs about 18 1/2" and is steady at idle (in park, no a/c, no brakes)

If vac looks OK you might then start looking at CPI. Here is one good supplier of new and reman CPIs. Really good cust service. But there are many places that sell these things and prices seem to vary widely.

http://www.lindertech.com/reconinj.htm


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## Co.45 (Aug 11, 2008)

im going to check it wed evening. 

i pulled the vortec cover and the IMT valve to try peeking through to see if they're leaking. i wasnt sure what to look for but i did see clean areas on both sides. the bottom of where i wasa looking in was wet and black but the wall leading down was clean?

its almost easier to take a pic. but id rather not replace the whole cpi if i can its too expensive cant i replace the nut kit and FPR. 



> if it is leaking there will be clean spots from the fuel washing
> the inside. Clean spots on the driver side indicate a leaking nut kit. Clean spots on the passenger side indicate a leaking FPR.
> If one of them are leaking you can replace just the one that's leaking, but a lot of people just replace both so that thay don't have to worry about it



i tried one time to see how much parts are online but nothing came up am i typing in the wrong names? 

ill get back with more info wed night! thanks


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## Raylo (Feb 12, 2006)

Yes, you can replace just the nut kit and/or FPR. I think you can also replace the individual poppets at the ends of the tubes, too, w/o replacing the central injector itself which is the expensive piece. If you do the FPR and nut kit and/or poppets make sure to order some poppet retainer clips (they hold the poppets in their ports). These things get really brittle and you will likely break a couple pulling them out. Linder sells these separately for $5.00 apiece. Oh, when you do the nut kit... the fuel line retaining plate is bolted onto the rear of the intake with a torx bolt that has red thread lock on it. These can be a ***** to get out w/o rounding. I had my intake off when I did mine so it was much easier than on the truck.

Also, be *very* careful with the injector electrical conector. It gets brittle, too and will break. Dealer charges ~$120 for a new CPI harness and they don't sell the connector separately. That is a lot of coin for a 2 foot piece of wire and a couple connectors. Don't ask me why I know this. :-/

Good luck!


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## Co.45 (Aug 11, 2008)

I found out what vacum line you were talking about the one going under the air intake, would that cause the reving?

I looked at both that were connetected there and to the front of the plenum. they looked ok did not replace but will get around to it. do you think this would cause the surging? 

i took off the upper plenum and took some pics it pretty much shows that both the kit and FPR need replaced. 

Damaged FPR and Nut Kit

so i will heed to your advice with the poppets and the connector ill be real careful with that...

more to come when the parts get here


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## Raylo (Feb 12, 2006)

It looks to me like the FPR is probably leaking. Not so sure about the nut kit but that is almost irrelevant as you need to replace it anyway when you do the FPR. Just handling those old plastic parts will stress them so they can't be trusted.

Another test you can do is with the plenum off turn the key on to pressurize the system to look for leaks. You should also do this after putting in the new parts before reinstalling the plenum. This will not check the individual plastic lines to each poppet injector as those lines only get pressurizd when the central injector fires so visual check will have to suffice. Those tubes come only on a whole new CPI, I believe.

Not sure what to tell you about vacuum. If all is connected it is proably OK. A vac gage check would help put that to bed.

Be very careful with all that brittle plastic!


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## Co.45 (Aug 11, 2008)

I do have one last question for ya!

So far im planning on buying the cpi line kit from linder 

becasue i cant find it anywhere else and considering chevy charged me 12 dollars for a elbow vacum fitting for my pcv valve i dont want to see what they will charge for a FPR and Nut kit

im also planning to buy the FPR from advance simply becasue theres is 43$
i know the one from linder is a late model one desinged to probably avoid the current problem i have now!

but i cant see myself spending 100 on it if i can buy one for 43 and maybe 100k miles later another one which would still be less than the linder one.

my question to you is you said poppets so that would be 6 then i read on the linder site there regulator kit comes with orings? will i need those (since theres is a different model FPR) and i also read in the haynes manual that i should replace the orings to the cpi i guess below it? my memory is fuzzy on that. but are those the same thing?

im just nervous basically i dont want to leave something out and not have a car for days!

so far im getting 
1. line kit 
2. oem Fuel Pressure regulator 
3. 6 poppets from linder if advance doesnt carry them (which they most likely wont)
4. upper plenum gasket

should i really look into getting the orings and are they just called cpi orings (both kinds if there is two) becasue it took me a half an hour of arguing to convince the A#%holes at advance that my truck had an fpr and nut kit and i did tell them cpi line kit and Fuel Pressure regulator! they assume if they never heard it doesnt exist!

anyways sorry for buggin you again like i said i dont want to forget anything and have to wait for parts.

thanks


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## Raylo (Feb 12, 2006)

Are you getting poppets or just the poppet retaining clips? The clips are what breaks. No, the local guys prob don't have 'em.

As for O-rings... I got the Linder FPR and there are a couple of O-rings (ow was it one?) that seal it in the injector body. I assume the stocker will have them, too, and hopefully they come with the FPR. The line kit (AKA nut kit) is supposed to come with the 2 little o-rings that seal the threaded connections of the fuel lines. These were omitted in my shipment from Linder but I got 'em at the dealer for a couple $. You might want to verify with Linder that they are in the package. The nut kit parts list had them on it but they were not present in my shipment.


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## Co.45 (Aug 11, 2008)

CPI Poppet Valve Retainers i'll double check that there sending the o ring with also.

thanks again cant wait till the parts get here so i can really see how this truck runs!


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## Raylo (Feb 12, 2006)

I hope this stuff gets your truck to run well. These motors are kind of finicky. And 1994 version being OBD-1 is good and bad. It's simpler than OBD-2 but some common issues don't throw codes so diagnisis can be a crap shoot... or turn into a money toss. Good luck!


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## Co.45 (Aug 11, 2008)

just finished putting both those in

the left line was cracked on the nut kit and the fpr was also bad
but yet it still idles up and down like two-four times and stalls out
i replaced almost all of the vacum lines up top? except the ones coming off the front and the the two going down and back over top of the tranny
could these be the problem.

i have yet to find anyone with a vac gauge im just going to look into buying one myself if there not to expensive

could the cap be causing this? also i was told by the original owner to check the timing? but i didnt see how that would have gotten f'ed up while changing the cap and plugs?


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## Raylo (Feb 12, 2006)

Too bad that stuff didn't fix the truck but looks like it needed done anyway. Vacuum gages are cheap, like $20. Timing is computer controlled so shouldn't be off unless someone removed the distributor and put it back wrong. You can do static timing but you need to pull a wire in the passenger underdash area first to take the computer out of the mix, then time, then reconnect. I've never done this so can't walk you though it. Could also be a worn out or broken distributor and probably some other stuff.

You could also visit these sites to get a wider audience for vehicle specific advice.

http://www.blazerforum.com/ - try engines and transmissions forum


http://www.s10forum.com/forum/ - try 262 c.i. (4.3L) V-6 forum


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## Co.45 (Aug 11, 2008)

update i just hooked up the vac gauge i had 20 off the ball looking thingy and when i went to uplug the vac line coming off the back off the plenum it ran ok??? 

im assuming this is becasue i have a pinched line somewhere unless one of those line goes to my evap canister but i could have sworn the line off the front of the plenum under the thorttle went to the evap canister?? could it be one of the lines going back to the transfer case? and would that be causing the problem of it sputtering while driving at constant speed? 


anyone have any ideas!!!???

aslo i did check the iac it was very clean? and wouldnt move but im not sure if it was supposed to?


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## Raylo (Feb 12, 2006)

20 sounds like a solid vacuum. The IAC is actually a stepper motor and will not move easily. That is normal. Yes, the vac line from below the TB goes to the purge valve for the evap system.

One wild shot I have read about over in the s10 forum is worn out distributors causing problems. But I think that would take many, many miles... and perhaps some bad oil change habits.

Depending on $ you might just change out the IAC, TPS, and O2 sensors. But if you can find someone with TTS Datamaster software you can watch the action of these devices and perhaps narrow it down a bit first.

Sorry, you've pretty much got me stumped. Maybe some of the TSF regulars can help?


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## Co.45 (Aug 11, 2008)

Im betting on the iac I've been told that three times so far and when i told the very helpful gentlemen on blazer forums abotu the vacum being good and it actually workign better with a huge scale vac leak he thought it was the iac.

im not sure if i can test it or not but im going to find out today!


and i dont know anyone that has that system. and i've been told and i read in the haynes book if its not one of the sensors you recomended outside of faulty electrical connections its either the cap or plugs are bad or were installed wrong or feul pump but that has been replaced prior to purchase. i was also told and read it could be cam shaft wear but i doubt it it only has 114k on it and a ex state police officer owned it and he wasnt a speed demon!

heres the forum where i was told the iac
http://www.blazerforum.com/m_172755/mpage_1/key_/tm.htm


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## Raylo (Feb 12, 2006)

Yeah, IAC would be the first thing to try. Luckily none of this stuff is terribly $$ or hard to change out, except maybe the O2 sensor. Access to that can be a little tough. Good luck and let us know how it turns out.


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## Co.45 (Aug 11, 2008)

chnged the iac out had issues with the change out nothing happened so i check the electrical line and traced it back to the relay and those had all kinds of gunk on them so i cleaned them out and fired the beast up and voila ran like a kitten then it shot me me a SES turned it off crosssed ground and diagnostic and it told me it was the iac so i cleared it pu tback in the new iac and tried again back to normal. and yesterday i replaced
both relays with the same luck tom im running throught the check list in the haynes book for stalling.


my bat doesnt really hold charg would a bad alt cause this?


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## Co.45 (Aug 11, 2008)

and when i say normal i mean lopeing and stalling!


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## gatewaygod (Aug 31, 2008)

something to try is the FORD wiggle test used by ford techs yes ford made a diagnostic tool FREE OF CHARGE LOL start it up start wiggling wires pulling pushing twisting, not enough to pull the wires out of the connectors just to see if there is any change in engine performance.


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## gatewaygod (Aug 31, 2008)

what i would suggest is a load test on the vehicle.
leave the vehicle shut off for a good 10 to 15 min

(the battery can still hold a residual charge if the engine was just shut off) 

have them do a battery load test (with the engine off) before they do a alternator load test, reason the same as above if the battery checks bad dont rule it out just yet, have them do the alternator test and if its bad i would try just replacing that first and if you still have a problem like hard starting due to low battery voltage etc. then replace the battery.

and YES a bad alternator could be the cause of those proplems.
most of the time when they go bad its the rectifyer bridge.
the part that changes the AC power to DC if the alternator is letting AC through those AC voltage spikes will cause very funky wierd things dealing with the computer.


hope that helps.:smile:

autotech zach



my bat doesnt really hold charg would a bad alt cause this?[/QUOTE]


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## Midnight Tech (Dec 31, 2001)

For those who saw what was posted by gatewaygod yesterday, he had posted unsupported claims that parts sold at any place other than the dealership are "seconds".
That is odd...I work in a parts store where we sell the exact same parts in many cases that are sold at the dealership and are even on occasion purchased from us by the dealerships. We have sold sensors, modules, coils, etc., that are actually OEM parts that have been purchased by the aftermarket companies and put into their own boxes. Most water pumps are remanufactured by only a couple companies and I've NEVER seen one that was just "cleaned and spraypainted". They are cleaned, disassembled, and reassembled and coated with an anti-rust spray - never painted.


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## gatewaygod (Aug 31, 2008)

Midnight Tech said:


> For those who saw what was posted by gatewaygod yesterday, he had posted unsupported claims that parts sold at any place other than the dealership are "seconds".
> That is odd...I work in a parts store where we sell the exact same parts in many cases that are sold at the dealership and are even on occasion purchased from us by the dealerships. We have sold sensors, modules, coils, etc., that are actually OEM parts that have been purchased by the aftermarket companies and put into their own boxes. Most water pumps are remanufactured by only a couple companies and I've NEVER seen one that was just "cleaned and spraypainted". They are cleaned, disassembled, and reassembled and coated with an anti-rust spray - never painted.


THEY ARE NOT THE SAME, AND THATS WHY THE "CHEAP AUTO PARTS STORE PARTS LAST SO LONG RIGHT"


YOU KEEP WORKIN AT YOUR PARTS STORE ILL KEEP BEING A TECHNICAN HERE IN THE GARAGE


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## FreoHeaveho (Aug 22, 2006)

Gatewaygod, please refrain from "yelling" at members and being rude at TSF. This is a family orientated forum, and as such we value all reasonable opinions. There is no need to devalue other's opinions here, and btw, no swearing.

If you would like to remain a part of this community please do, but do it in a respectful manner.


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## Co.45 (Aug 11, 2008)

I'm Cheap

I've Been Buying Cheap parts for my cheap cars since i been able to fix them Fuel pumps spark plugs cap rotar wires radiators brake pads FPR Nut Kit ALL Cheapest i could find no problems yet.

No Offense though its just like computers some people dont like gateways becasue they had bad experience but its not about the company as a whole its about that one experience! (And in my opinion all pc companies put low end materieals in there towers) I believe what happened to you is possible but it doesnt mean there all bad everywhere i went into a auto pars store and i went to buy a relay and it took me 15 min of arguing to try to convince the store clerk that i wanted the part but she wouldnt sell it to me becasue when she opened it up it looked like someone had used it!
she made me wait another day for a new one to come in!

just like it was said before everyone is entiltled to there opinion 
I had bad experience with LG recently sold me a broke choc and now they wont fix it but that doesnt make me think all LG is garbage IM not going to run to return all my plasmas and LCD's becasue i got a 1st gen cell phone that had a bad chrager port! 

Anyways thanks for the Advice with the ford test i did a quick version of it yesterday but i need to acutally rip some of these wires down and make sure there connected my first test is the TPS and IAC And i really do think my alt has a big deal in this day time i ride the bat is at 14v then as soon as the engine stalls or is turned off (stalls more than its turned off) the bat drops down to 12 withiin seconds and if i roll any windows down it will got down to 10 or 8 and while i run at night with lights on its at 12 the whole time engine is running?

did have bat tested came out good (i should have rolled windows down before test it wouldnt have passed 

Im giving this beast one more week of testing then im giving in taking it to the GM dealership directly behind my house they want 84 dollars to diagnose the problem! 

ohh and i just recently paited my truck OD Green doing the camo thing is there any topics on such a thing in this forum?


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## Co.45 (Aug 11, 2008)

Quick question? Well knowing me it will be long but i fully intended to make it quick before i started typing!


I just recently redid my winsheild seal. The track was very rusty had to do it and like i said above im cheap so i did it myself went through without a problem outside of scrapping and sanding down all the rust in the track!
cost me 6 dollars for the tube of poly and i had sand paper left over from the paint job i just did!

a tad bit cam trhough in one spot front right passanger side (top right)
so that would explain a little bit of the smell?

but two days ago i figured out that i have been a complete idiot ever since i first got this truck i think im going on 5 weeks now i put in a referbed digital dash console that is great i only paid 60 dollars for and its covered for life!
when i was doing that i pulled my dash around the steering wheel out including the hvac controls ( 94 S10 blazer tahoe lt) when i pulled them out it was really tight i mean i had to pull with alot of force on the vacum lines connecting to it to give me some room to squeeze my hand in there!

anyways after that i put everything back together and it works like a dream (the dash that is) the hvac control knob on the right (chooses ac vent defrost and off) wouldnt slide down into the off position and i assumed i messed it up and thought it was off i just meessed it up well two days ago i got frustrated playing with it and banged it down with alot of force and it went into off and made that noise vacum letting go! so that was cool that i was driving around in my truck for id say 3-4 weeks with the ac that doesnt work in the first place on max ac!

so now im running the same but the truck is letting off this terrible smell almost like burning plastic??

sorta smells like its coming from the underbody but i got under it and smelled everything same with compartment double checked no vac lines or electrical where touching and it seems good but im still smelling that smell ?

only thing i could think of is some of the old sealant from the windsheild fell into that little vent looking thingy right there below the winsheild (on the outside) i know some did but i didnt think it would make that big of a stink??


Any Ideas!! ??

Sorry for it being so long i feel if i include the whole story then your better prepaired to assist.


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