Hi Everyone, I'm between thirdgens right now, but I'm having a problem with my '91 full size Blazer. it has a stock 350 TBI, everything is stock except for the 3" catback flowmaster exhaust. New O2 sensor, cap, rotor, plugs and wires, IAC, TPS... Truck runs great at startup, and for the first 5 minutes of driving, then it seems to develop a slight miss at low rpms, and gets a very strong exhaust smell. Pulled the exhaust and the cat seems clear and not plugged up. It will occasionally stall at intersections and likes to stall at low throttle in reverse... I've read other places that I should not be running a 180* thermostat and that it needs to go back to the stock 195* thermostat. I'm contemplating pulling the throttle body this weekend and doing the complete gasket set and installing new injectors as well as finally replacing the thermostat. The truck never really gets above 175* even on The hottest humid days. Any other ideas or things I'm missing? This is my Daily driver, so it needs to be right. I'm running out of ideas and knowledge. Thanks in advance. This site has always helped me tremendously with my old IROC!!!

 

I forgot to mention that i already replaced the fuel pump, and the intake manifold gasket was leaking so we replaced it as well as the tbi base gasket was shot, and I'm confident there are no vacuum leaks, and I scanned for codes repeatedly, everything seems to be working...

 

Have u checked the fuel preassure regulator ?

 

No, it never dawned on me to check the regulator... I've decided to hold off on the injectors, but I'm goin to tear down the throttle body, give it a thorough cleaning, and put the gasket kit into it tomorrow. I guess I need to research how to check the regulators on these now...

 

Ok, fun night in the shop... Got the BWD TBI rebuild kit with the new diaphragm for the fuel pressure regulator. Took it all apart, four cans of throttle body cleaner later she is looking a lot better. A few of the vacuum ports were pretty filthy and clogged up with greasy gummy crud. Got her back together with all the new parts, and she fired right up almost instantly!!! Usually had to crank a few revolutions. I took her for a 20 minute run, lots more power, and now when I let off the throttle she coasts. Not as much of a strong exhaust odor, and I didn't notice any of the rotten egg smell. Much smoother acceleration and idle is noticably lower, no tach so I'll have to check it and make sure it's set correctly, but when I drove home and went to parallel park on my street in reverse, she almost stalled again... EGR valve??? I'm curious what kind of fuel mileage I get this week, so far I'm up to 15 mpg around town, when I got it I was only getting 11 mpg... So what do you guys think. The EGR valve looked pretty crusty, and I'm guessing it original and never been touched. Another thing I was thinking if the vacuum
ports were gummed up, wouldn't it stand to reason the vacuum line would be pretty gummed up as well?

 

Vacuum leak. Find a shop with a smoker and get it smoked. This is the fastest and most accurate way to find leaks. It's called a "lean stumble".

 

Did you ever figure out your ultimate problem?? I am looking at about the same thing you are....read my post "Not a 3rd Gen, but TBI..."

I haven't pulled my TBI or Intake yet, but doesn't seem to be a vacuum leak. Let me know!
Thanks!
Ryan

 

Two weeks ago I did the full gasket kit on the throttle body, Took a few hours to disassemble it, clean it and install all the new gaskets. I bought the bwd kit from advanced auto that came with a new diaphragm for the regulator... Ran a lot better, but still had a slight stumble at part throttle, and in reverse. I did finally resolve this, it was my egr valve. I didn't think it was, but once I pulled my egr valve, I realized that it was sticking and not functioning 100%... new egr valve and it was fixed, runs like a new truck now!!!

 

Thanks for the Info, I've been suspecting the EGR valve for some time, but I had it unplugged and didn't really change a thing. I am guessing it is stuck, so even if it is unplugged, it does nothing. I will try a new EGR, can't hurt I suppose! What brand did you pick up?? Where did you get it?

Thanks!
Ryan

 

I just bought a BWD brand from advanced auto, it was what they had in stock for $79.56... Compared to ordering the original at $130... I wasn't 100% positive it was going to fix the problem so $80 seemed expensive enough to me. Keep us posted what you find.

 

I am still fighting it, haven't replaced the EGR yet, but its on my list of things to do. Money is a big tight, and its my Anniversary today, so I guess I have to take the wife out and show her a good time. Ill probably have to wait until the 15th to pickup a new EGR, and I am also going to pick up a new distributor. I noticed red dust in the cap the last time I had it off, so I know that it is on its last legs anyways. Peace of mind thing I guess!!

By the time I'm done with this, Everything on the engine will be brand new! Ugh...oh well.

Another question for you, I've asked it in my post, but noone seems to want to answer me. Inside the distributor, my pickup coil moves back and forth, like spins, and I am not sure if it is supposed to move at all. And if it is supposed to move, this one is probably not moving correctly, seems hard to move, like it is hanging up, and the windings look rusty.

Thanks for the help!

 

Well you pretty much stumped me on that one, I've never had to deal with the pickup coil yet. From doing a quick search, it looks like the biggest problems are with the wires coming loose, cracking, and shorting out... This did make me feel better though, now I know I haven't replaced every part on mine!!!

 

I too am having problems with the idle on my 92 Jamaican Yellow bird with a 305 TBI. Just did a full engine rebuild and get the stumble on the idle, the bouncing rpm's, and dying occaisionally when stopped and in gear.

I went to replace the pickup coil. You have to drive a roll pin from the distributor gear, then slide the shaft out of the housing. I ended up putting mine in a vise and had to twist and pull. Long story short, I was worried that I bent the shaft. I replaced the whole distributor for $80.

I had one magnetic pickup on a Ford that would lose magnetism. It would run every morning for 17 seconds then wouldn't restart. Changed the pickup coil and everything went well.