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Bucking and Back Firing-HELP!!!!

Recon!

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Columbia, SC
This morning at about 0300 I was driving home from work. I took my normal route over some railroad tracks and I hit them at about 40-50, just like I do every day. It's a pretty good hit in a leaf spring 4x4, in my Sierra it's much easier to take. Right after I went over the tracks, the motor started back firing like crazy. Would barely make any power, was bucking all over the place, and would barely idle. Luckily I was only about 1/2 mile from my apartment! When I got into the parking lot, it died and would not restart. I cranked on it and did some magic gas pedal work to get the thing to drive nearly all the way into the parking spot where it promptly died again and would not restart. I had to push it the last few feet, it sucked.

Today I come back for lunch to take a quick peak at it to see if something came disconnected or what not. Everything is attached in it's appropriate place and no wires that I can see are rubbing on anything causing a short. I am a pretty good self mechanic, and this one has me flustered, to say the least. I use the Blazer for DD duties to keep the mileage low on the Sierra, but obviously I can't drive it right now.

I can get it to start, but it requires longer crank times than normal, and it is stumbling and bucking at idle really bad. It surges at probably 200 rpm but constantly wants to die. I can give it a little gas and it tries to smooth out and bring up the rpm's, but it still back fires and stumbles. It is clearly not drivable in it's present state.

The only thing I can think of, is that the timing somehow jumped when I hit the tracks.

I don't have time to pull the cap off the distributer, but I hope I can get home from work at a decent hour today to mess with it.

It's a 1989 Blazer, stock TBI 350 with a throttle body spacer, 700R4 trans. Fuel filter a few months ago, plugs/wires/cap/rotor/coil about 2 weeks ago. When I did all the ignition stuff, it ran better than it ever has in the 6 months I've owned it, but obviously today is a new day.
 
Not the cap, rotor, or knock sensor.

Sprayed out every electrical connection with some fancy electrical spray chit that cost $2, have to wait a few hours per instructions on can. Replaced a ****ed piece of vacuum tube that I had apparently missed when I did that job a few months back, and capped off a vacuum hose barb that I have no idea what it hooks to. It looks like it hadn't been connected to anything for a long while, and I couldn't find any open spots to try it on. We shall see.

Also found a blown fuse attached to a fairly good size wire right after the distribution block on the fire wall. Replaced it, too.

After I eat dinner I will see if it lives again.
 
I fixed it all by myself

So I started it up and it runs fine now. Decided to run some SeaFoam through it, and my god what a smokey nasty treat that is. I poured it right in the throttle body, ran some down the vacuum line, and poured the rest in the gas tank. It smoked hardcore for a while. Good thing it's windy, I wouldn't have been able to see or breathe.

Drove it to Wal Mart to get some crack-I mean some energy drinks-and it seemed like it was a little goofy still. A few miles after I left the house, it threw the Service Engine Soon light and it remained on for the rest of the trip to the wal. After my 6 minutes of shopping/stalking a hot chick who must have been a swimmer, I got back into the truck, started it right up with no SES light, and drove home without incident. It feels like it wants to stumble at idle just a smidgen, but that might be the SeaFoam playing games with me. I'll finish this tank of fuel off and then change the fuel filter to see if everything is still yummy.
 
Could have been bad gas. My truck did that before. I guess you'll find out soon enough.
 
I'd still pull the codes. Even though the SES light is off, there are codes still in the computer.
 
How do I do that without a scan tool?


Look for the "Trouble Codes" sticky in the Fuel Injection Section of the forum boards. It tells you not only what the codes mean, but it tells you how to pull them using a paperclip. Trust me, it does work. I've used that method so many times I've lost count.
 
Look for the "Trouble Codes" sticky in the Fuel Injection Section of the forum boards. It tells you not only what the codes mean, but it tells you how to pull them using a paperclip. Trust me, it does work. I've used that method so many times I've lost count.

Thanks!:bow:
 

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