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My '92 S10 Blazer loses power intermittently under virtually all driving conditions. It sometimes stalls at stop signs but starts right back up. I checked fuel pressure and monitored it for a period of time and the fuel pressure is alway between 52 and 60 psi. When it stumbles, if I hit the intake with some starting fluid or gas, the engine picks right up.

I replaced the MAP sensor and checked the engine error codes. There are no error codes. I then replaced the CPI unit (twice) and got no improvement. I replaced the throttle position sensor and distributor module. I still have the same problem. Any suggestions?
 

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Could be the EGR valve. The service manager at the local Chevy dealer told me they could get a piece of carbon stuck in them. He said the 4.3 was pretty bad about that. Try taking it off and cleaning it with carb cleaner. With it removed you will see two holes in it. One is open and the other has a plunger in it. You should be able to push the plunger in with a screwdriver real easy. If not you may need to replace the valve. If thats ok clean it out with carb cleaner to get the carbon out. Since your fuel pressure is good it shouldn't be the fuel filter but if it's got over 40k on it I'd replace it.

Shane
 
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yeah those older blazers have problems with the EGR system gettin clogged up..and also...the CPI unit ot the Injector Unit or Fuel pressure regulator..they are all the same thing....but they are known to leak...a lot also....the only way to check that is to pull the plenum...soo...just some thoughts
 

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I have had the same problem with my 94. It went on for about 2 months. Now it wont even start. I have heard some things about this CPI... like maybe thats the problem.

Can anyone tell my what exactly it is and where I can find it on my Jimmy?

Im lost on this one and any help would be greatly appreciated.

Thanks, JustXJ
 

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Continuing saga

I replaced two of the CPI (Central Port Injection) units, figuring that the first one might have been bad. Same problem. I went ahead and replaced all of the rest of the sensors...oxygen, MAP, throttle position, intake air. Same problem. I ruled out the catalytic converter when I took the oxygen sensor out because the O2 sensor leaves you with about a 3/4" hole in the exhaust pipe ahead of the catalytic converter through which to exhaust. I made a voltage check at the connector to the CPI unit by disconnecting the connector and inserting a pair of jumpers across it so that the circuit would still be made up. I started the engine up and at an idle (when it would idle) the voltage is approximately .111 volts. When it would take any throttle at all, the voltage would rise to about .4 - .5 volts. The engine would go lean and stumble within a second of the voltage going down, which it would do on its own accord. All this while there are still no error codes showing on the engine and still feeding starting fluid or gas to the inlet of the engine it would immediately pick up. At this point I thought that the only problem left would be the wire going to the ECM (Electronic Control Module) or the ECM itself. I took the plastic covers off from under the dash so I could see the ECM and it appears that it has bundles of wires plugged into it here and there. I called the local GM dealer to price a new ECM and it was $223 for a remanufactured ECM. Also, they said they though it would be about $150 to install it. At this point, and after looking at those bundles of wires and knowing that the ECM is a Motorola computer I was more than certain that I didn't want to replace it myself. So today it went into the GM shop and came out running very good. $400 seems like a fair enough price for replacing something of that much complexity. The only word of caution here is that if you make that voltage check at any of the sensors or the CPI unit you must be certain not to short the connectors and/or overload them with a low-impedance analog-type meter. I guess that's about it. Good luck, all.
 
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