[stocked]

93 AWD with the Vortec 4.3, i just got it and it stumbles badly, i replaced plugs, and dist. cap and rotor button along with the fuel filter. Doing all at once helped some and made it easier to start. I haven't checked fuel pressure yet though to rule out the pump being weak. But it is hard to start, runs rich as hell (exhaust smells more like gas then exhaust), has poor power most of the time. Although if i floor it from a stop it bogs to about 20mph then takes off running pretty good, almost like normal. But sometimes sputters/cuts out. Just not all the time. if i give about 1/5 to 1/2 throttle it goes OK, but not like it should. Like a really bad miss almost. I think it would be the cpi injector is bad or that the cat is very clogged. But if i leave it sit overnight it starts easier, like an injector is leaking and the extra fuel in the cylinders helps it start. I didn't replace the plug wires but i plan on it tomorrow or Monday so I'll see if that helps any. And i almost forgot.. is it possible with a normal distributor system for one side of the motor not to have fire? I pulled a couple plug wires to the driver's side bank off the distributor and it runs about the same with them off.. So could i have just bad plug wires, or maybe something worse like a bad head or head gasket on that side causing no compression? I know i put alot of info, but i'm just trying to get this pig running right before snow fall.

Thanks!

 

[ASTROJOE LT1]

Welcome to AstroSafari.com. There are a lot of members here ready to help you with your problem. My 1st guest would be the Cat is plugged up or the ECM is reading wrong. I am sure other members will give you some more advice.

 

[Big_kid]

Welcome aboard!

When you pulled the plugs on the driver 's side, what did they look like? Color/condition/contamination?

Sounds like it's out of left field I know, but is the coolant full with no air pockets?

:chevy:

 

[ghostrider1061]

if you pulled off plug wires and it ran the same, did you put the wires back from where you got them? you also mite want to check the firing order. wires mite be crossed. just a thought. :2:

 

[Mr_Bowtie]

After you verify you have the plug wires hooked up right:
Sounds like my '92 when the CPI was leaking under the plunem. There is a black circular sensor on top of the plenum that you can remove and then look down in there with a flash light to find out whats going on. If you see any washed out area or puddles of fuel you got a leak. I got lucky and it was my fuel return lines and fuel pressure regulator leaking. Did exactly what you said wouldn't run good at all and warm starts were almost impossible. Its worth a peak as it will only take you 30 minute to pop the dog house off and take a look.

 

[stocked]

To try to answer all the questions... Yes the coolant is full, not sure about air pockets but i do know that i have good heat. so?

I decided to climb under it earlier before work and discovered a nice 2 foot piece of 3" pipe welded it. So no Cat to be clogged.

All the plugs were pretty well worn, but the driver's side seemed to be in a LITTLE better condition then passenger actually.

Yes i put the wires back where i got them on the dist. But its a possibility that they were crossed before i got in there too. So i'll check it tomorrow. 1-6-5-4-3-2 right? And cylinder number one being at the eleven o'clock position when looking at the distributor from the back of the motor (inside the cabin with doghouse off)?

Lastly, the CPI being bad is my worst case scenario here (atleast to me). I'm not wanting to drop $280+ for a new one within the first month of owning it lol. But you gotta do what you gotta do i reckon.

 

[Leeann_93]

No, the parts he's talking about are total about $100 - less than $40 for the fuel pressure regulator (it is replaceable separate from the CPI) and the fuel pressure and return lines (aka Nut Kit) are about $60 at NAPA, among other places.

Doesn't take that long to do, either. Unhook a couple sensors, unscrew a group of 10 mm bolts, unscrew 2 Torx Security screws (comes with the FPR); installation is reverse of removal. I don't know what's involved with the nut kit, but it isn't too much more than the FPR.

 

[stocked]

But i thought from my experience with S series trucks that the injector "poppits" became dirty and such on the cpi. I have yet to hear about the fpr and return line problem until now. I kinda hope thats just the problem. I'd drop $100 tomorrow on it to get it done and over with lol.

 

[Leeann_93]

They will tend to. GM put out a TSB on that issue, basically telling mechanics to do an upper fuel system clean with the GM top fuel cleaner (concentrated Chevron Techron) and tell the customer to use higher-quality fuels. I just put concentrated Techron in every so often and everything's cool now.

Before you spend any money, check it out and make sure that's the problem. Pull the 'Vortec' cover on the top of the engine, then disconnect and pull the IMTV (round thingy underneath) out. Gently. Use a gentle twisting action; you might have to spray a little WD40 or something around it, then twist gently until it's loose. It has an o-ring you need for reinstallation (lightly coat it with engine oil before you reinstall). Then look inside with a flashlight. If there are washed areas (they will look golden vs. the black of carbon buildup) on the passenger side, it's the FPR. If there are washed areas on the driver's side, it's usually the nut kit. If there are no washed areas, that part might be okay.

Then pull the EGR valve and check it for carbon buildup. Often, chunks of carbon keep the pintle from seating fully, so that needs to be cleaned, then reinstalled with a gasket from the HELP! section of your autoparts store (it's generally $5) that has a screen on it to keep the bigger chunks from getting to the EGR.

After that, pull the IAC valve and check/clean the pintle, then reinstall after lightly lubing the o-ring with some more engine oil.

I forgot to mention you'll need the about $12 upper plenum gasket for reinstallation if you do pull the plenum.

I had to replace my FPR, clean my EGR and IAC, run seafoam through the vacuum system and put Techron in the tank when I bought my truck. My nut kit was okay. You said the driver's side plugs looked better than the passenger side? Then, usually, the nut kit is okay (the plugs will be black if there's extra fuel).

But, please: check stuff out before you spend money. We can diagnose your truck for you, but unless we actually see it we might not be right. I don't want you just throwing parts at it on our say-so.

 

[stocked]

Well as of today i'll definetly need a cpi and whatever the "IMTV" is, along with a new plenum seal and the pigtail to the cpi.

bottom line is... Slight fire when we pulled the plenum lol. My nephue cranked it over while it was off and pop, flames. But i got the plenum over it best i could to save the wires and dash, and hit it with a good old extinguisher. :screaming:

Also, can anyone tell me when the trans control went to Electronic? because i dont have a tv cable hooked to the throttle and i wanna know if my trans is going to toast when i get it running again.

 

[Leeann_93]

4L60E was released in '93.

I'd hit a pick-n-pull for the IMTV. But not for the CPI or the pigtail. Try www.lindertech.com for the CPI, along with www.rockauto.com and www.gmpartsdirect.com

If you had a fire under there, make sure the fuel pressure and return lines are okay. They're plastic.

 

[stocked]

4L60E was released in '93.

I'd hit a pick-n-pull for the IMTV. But not for the CPI or the pigtail. Try http://www.lindertech.com for the CPI, along with http://www.rockauto.com and http://www.gmpartsdirect.com

If you had a fire under there, make sure the fuel pressure and return lines are okay. They're plastic.

I just thought about that after i got home actually. If they are toast then would a j/y be the best source for them too?

 

[Leeann_93]

If you had a fire under there, make sure the fuel pressure and return lines are okay. They're plastic.

I just thought about that after i got home actually. If they are toast then would a j/y be the best source for them too?

No. They tend to get brittle with age and if you have to remove them, you really need to replace them.

 

[stocked]

If you had a fire under there, make sure the fuel pressure and return lines are okay. They're plastic.

I just thought about that after i got home actually. If they are toast then would a j/y be the best source for them too?

No. They tend to get brittle with age and if you have to remove them, you really need to replace them.

Who would sell them? I'm guessing it would be a GM only part.. :banghead:

Also forgot to add, that before it burnt up it wouldn't hold ANY fuel pressure, but pump was working fine. So i'm guessing that the FPR was bad? Also i didn't have any leaks i could SEE

 

[Leeann_93]

Nope, NAPA has them, along with GMpartsdirect.

That's usually the check valve in the pump, if there are no visible leaks around the FPR and it won't hold fuel pressure. That's a non-replaceable part, of course; you have to replace the whole pump.

 

[Mr_Bowtie]

When I replace my fuel return lines and fuel pressure regulator the cheapest place for them was a auto parts warehouse that I found on eBay. Napa was the most expensive and Autozone wouldn't sell me the fuel pressure regulator without buying the whole CPI kit.

Sucks about the fire, but hopefully it all works out good for you.

 

[stocked]

Nope, NAPA has them, along with GMpartsdirect.

That's usually the check valve in the pump, if there are no visible leaks around the FPR and it won't hold fuel pressure. That's a non-replaceable part, of course; you have to replace the whole pump.

I don't think the pump had anything to do with it. It would pump gas but it got shot right back out of the return line at the cpi. I'll put a cap nut on the fuel line and see if it holds pressure that way. either way i still have to get a new cpi, lines and pigtail. But the good news is that i have a fuel pump from my old 92 Jimmy with the Vortec that i took out before i scrapped it for a thrown rod and rusted out body. So atleast i don't have to buy a new pump.

 

[Mr_Bowtie]

The return lines/nut kit probably have cracks in them. You should take some pictures while you doing the work and share them with us. We could use some good pictures on this very issue that plagues most of us CPI owners one time or another. :banghead:

 

[stocked]

The return lines/nut kit probably have cracks in them. You should take some pictures while you doing the work and share them with us. We could use some good pictures on this very issue that plagues most of us CPI owners one time or another. :banghead:

I wish i had thought about that before i got it done. But i do have an extra lower intake now if anyone needs one or i could do a mock up for a walk through! lol. Doing this was surprisingly easy. If i had opted to unbolt the passenger seat and remove it then it would have been cake. The hardest part (atleast to me) was getting the lines back into the CPI, but a little oil on them and some good wiggling and they popped in pretty good. I am really low on cash at the time so i opted for a j/y CPI that i pulled from a good running blazer with a crushed back end. Its from a 94. the poppets looked clean and the LIM showed no signs of the CPI leaking (even black all around). I also used the feed and return line from the donor as the new ones were $55 and thats the cheapest i priced around here. They were still fairly flexible and not cracked. I got the entire lower intake, lines, cpi, pigtail and all for $50, which i think is a steal. All i had to buy was a Plenum gasket. Also a good tip for the other "CPI'ers" out there... Check to make sure the fuel lines are all the way seated in the CPI and that they are hooked into the clip. I didn't get mine in and the feed popped out and almost filled the lower intake with gas lmao. So i had to soak it up with some old towels.. As of right now i have no idea if it will even start because the battery was dead so i left it on overnight slow charge. So i'll have a yae or nae in the morning as to if its fixed for good! Thanks for all the help.

 

[Mr_Bowtie]

$50 for everything you needed you can't beat that! Let us know how it goes in the morning.