Rich Exhaust

[wheels87k5]

I have an 87 blazer w/350 tbi....with the exception of a bad transmission, it ran good...I replaced the transmission, and gave it a tune up consisting of new cap, rotor, plugs and wires...now it boggles down at partial throttle...and if I hold it there for a few seconds it gives me a code 45---rich exhaust...I do agree with the code because the exhaust smell is strong and you can see a faint smoke from the tail pipe...I listed this problem under "fuel injection rejection"...the manual says to check the fuel pressure regulator vacuum control hose for the presence of fuel...where is it? I have replaced alot of components including fuel filter, fuel pump, tps, ecm, o2 sensor, map sensor, fuel injectors, fuel pressure regulator. The truck will start fine and idle good until you play with the throttle then will have a very fine surge. If you put it in gear and try to drive it, it will boggle down and not want to run until you put it back in park or neutral. It will rev good on wot. I have also checked for vacuum leaks and found none. HELP

 

[dyeager535]

I'll give you another thing to check. Is your EVAP setup working correctly? I'd check the line from the EVAP cannister to the TB, then remove the line and cap the port on the TB.

Manual also says to disconnect the map sensor connector and see if the problem goes away.

What manual are you working out of? I've got the troubleshooting portion of a GM TBI manual (description, culprits, flowchart) if you need it, just PM me an email address that will take a 613kb PDF.

 

[wheels87k5]

The evap line was already blocked off at the tb before the problem occured...that's the line that goes to the purge port on the cannister?...the other line to the cannistor is hooked up, it goes to the tank...The manual I have is Haynes. I unplugged the map sensor and the problem did not go away.

 

[wheels87k5]

Solved the problem with the engine boggling down at partial throttle while in park...and boggling down when you put it in gear...it was the EGR soleniod...a $15 part....now for some more fun...I found out that this motor came from a 91 Chevy pickup...not a blazer...that's how I found the correct part....when you look up EGR solenoid for a Blazer, it was completely different from what I had, and the Blazer part was $55. I can now drive the Blazer down the road, but after about 5 blocks it starts cutting out...and it has a fairly strong exhaust smell with some light smoke....put it in park and it sounds good...we'll work on it....Thanks members of CK5 for your help in getting this 87 4x4 going...all of your input and information from the GM manual got me this far...I'm almost there. Again, THANK YOU !!!!!!

 

[jamber2541]

Manual also says to disconnect the map sensor connector and see if the problem goes away.



not to hijack, but if you unplug the map sensor and the problem goes away, what would that mean, (what would the problem be?)

 

[dyeager535]

Would mean the MAP sensor CIRCUIT (vacuum lines, ports, map sensor, wiring) has something wrong with it. The ECM simply defaults to pre-specified values.

 

[DavidB]

Mine ran rich, now runs a couple seconds and dies. Ever figure it out?

 

[wheels87k5]

The EGR ended up being the main problem....I didn't want to replace it at first because of the cost, but after replacing everything else, I decided to replace the EGR anyway.

Problem solved. Truck runs great.