Hey everyone,

Last summer I picked up a 1992 4x4 with the CPI engine in it. This is my third s10 however it's the first CPI unit and I'm just at a loss at this point. It ran great For almost a year with just simple little fixes being done here and there. However, it started stalling out on me every here and there. It started as just a problem most frequently when I was coming to a stop, then progressed to when I was idling as well, then eventually it got to where it would start stalling and die when I'd be driving and even would stomp on it. Now it's to the point where it's barely driveable and usually takes a few minutes of sitting before it will go anywhere after it dies. I've replaced almost everything I can think of at this time, includingcv valve,map sensor, throttle pos. sensor, ignition coil, new distributor cap rotors and plugs and coolant temp. sensor in the spring, new plug wires, oil changes and air filters (of course)and just finished with the fuel pump, sending unit, relayand filter this week. I just took off the tuning valve and it didn't appear to be any leaking of fluid from what I could see but its still possible. Also I've read on here about checking the egr valve which I have yet to do, but any tips on how to do that as well as any other suggestions would be great!!

Oh while I'm on here, my gas gauge still isn't working even after I replaced the sending unit, it for the most part stays between 1/2 and 1/4 tank, with every now and then it works. Any suggestions?

Thanks again!!

 

First impression would be a clogged EGR valve. It should be fairly easy to remove and clean up. I think it is vacuum controlled on your truck which requires some care in cleaning it. You do not want to get any of the carbon cleaner (EGR cleaner) onto the vacuum diaphragm. If you do, it could weaken it, causing it to leak and the valve to fail.

If the EGR valve turns out to be clean or after cleaning it (you should clean it anyway while you have it off), the problem persists, I would next test the fuel pressure. The fuel pressure test port is located off the back of the intake plenum between the distributor cap and the brake booster, but closer to the brake booster. You will need to get a fuel pressure tester.

Hope this helps!

 

Hey Swartlkk,

That's kinda what I was thinkin it might be which I haven't gotten around to checking yet. Now I have a repair manual (haynes) and from whatit says I'm supposed to even remove the intake plenum to remove the egr valve. Is this the case, or are they just lying to me again? Also, as far as on the outside of the plenum there's no vaccum lines to the egr just an electric plug so any other tips on the cleaning that as well?

Thanks again!

 

Oh ok, I could not remember when the electronic EGR valve came into play. I thought that it could be on all CPI motors, but could not remember so I threw that disclaimer in there.

Anyway, you should not have to remove the intake plenum to get at the EGR valve, but it can be fun!

 

You don't have to remove the intake plenum but, as Kyle said, it can be fun.

You'll need a 10mm socket with at least a 9" extension for the driver's side bolt. For the passenger side bolt, you'll need a 10mm wrench - I find that a ratcheting wrench works really well.

Oh, and stick a little piece of paper towel in the socket so the bolt sticks in there better when you get it loose.

 

I got the egr valve off and checked it out and it was sticking really badly sure enough. SoI cleaned it out and got the plunger so it'll move smoothly but I'm still having problems!!! I have a fuel pressure tester alrready but I don't know ifI can trust it for sure or not, but even if I got a low pressure reading what would that indicate? I already replaced the pump, sending unit, and filter, and I always without a doubt hear it turning on and running. I was wonderin if maybe I could still have a clogged fuel injector? I've run three bottles of cleaner through the tank but is it still an option? If so, what are some recommendations? anything else I can check for? I really appreciate the advice whereas my car is the only one with 4x4 and we've gotten a foot of snow just today!! The help is much appreciated!!

 

Pull the IMTV in the intake manifold and see if you see any washing - you might have a fuel pressure regulator leak. This also would cause the carbon issue in the EGR valve.

You'll need a Torx T30 to pull the 'Vortec' plastic cover, then a T20 (or 25) to pull the IMTV. Be very gentle; spray some WD40 around the edges, then gently twist back and forth until it loosens and comes out. There's an O-ring on it that seals it to the manifold. When you reinstall it, lightly lubricate it with engine oil.

Once you've got it out, look on both sides to see if you see any puddled gas or washed areas. If you do, the passenger side = FPR, driver's side = nut kit (usually)

 

I actually have already pulled IMTV off and looked (saw it on another thread) and I couldn't see anything that would really make me suspicious of a leak on either side, both have a lot of carbon built up on the FPR and Injector assembly. The EGR wasn't really all that dirty inside of it, nothing that wouldn't be normal, the plunger was just sticking so obviously I cleaned it out.

 

Hmm...have you looked at the IAC valve?

Also, the gas gauge not registering is probably a ground issue - check all the grounds near the tank for any signs of rust or corrosion.

Did you replace the wiring harness for the fuel pump while you had the tank down?

 

That I haven't looked at, what would I be looking for in that?

When I had the tank down all I did was replace the sending unit and all that jazz.I never replaced the wiring the sending unit plugs into (which I'm assuming is the wiring harness)