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EA81 MASSIVE backfireing problem...
Posted 07 November 2003 - 09:06 PM
I recently blew an air suction valve, and had to replace that, and the silencer as it was melted. Those seem to be working fine, but some plastic got sucked into the carb.... I dug out all the plastic I could see, and she runs fine now - except for the backfireing.
The backfires are so bad, that my passenger the other day thought he had been shot, and it's blown about five VERY LARGE holes in the muffler.
What to do? Time for a weber? I had small backfireing on my wagon, and when I put the weber on, it all went away - never heard another peep out of it.
I don't really have the money for a weber right now - can anyone recommend a good brand of rebuild kit for the hitachi? I can rebuild it myself, and have some experience along those lines, but I don't know where to get the rebuild kit. Also - specifically what in the carb could be blocked that would cause this backfireing? I'm guessing some plastic has eluded me......
Posted 07 November 2003 - 09:48 PM
At the air suction valve connects to the plastic bell. Take that apart and stick a quarter in there. Just to test it start it up and see if it backfires. This trick was told to me by someone who has done it a number of times. It may or may not work. But, it's worth a shot. If it solves the backfire then I'd just disconnect that system.
Posted 07 November 2003 - 10:01 PM
Posted 07 November 2003 - 10:18 PM
Posted 08 November 2003 - 02:47 PM
Am Having a backfire problem, as well. I'm just a Sunday afternoon mechanic, and I'm not sure where, in that mess of vacuum connections, the air suction valve is. Can anyone help this duffer?
Posted 08 November 2003 - 04:52 PM
Posted 08 November 2003 - 06:15 PM
cause thats what i'm gettin now since the engine swap.. the swapped in engine had one asv on it, so i had to use one off my other engine, so maybe the asv is bad on my spare engine that i put in?
cause the old engine never did it at all...
Posted 08 November 2003 - 07:50 PM
I don't think the cause of the problem is actually the ASV's, but rather an effect brought on by them working correctly, and introducing too much unburnt oxygen into the exhaust stream. If this oxygen is not used by the cat, then it causes an explosive mixture of fuel and air in the tailpipe - which spontaneously ignites when exposed to the hot exhaust. I have a feeling the problem is actually several things - possibly a weak cat, combined with a carb that is running too rich. My EGR is fine, and my anti-backfire solenoid checks out, so that is my hypothesis at this point. We'll see if reducing the amount of oxygen in the exhaust by blocking the ASV helps or not. I think if it does, I will simply remove the system entirely.
Posted 09 November 2003 - 06:01 PM
Thanks for the tips. Yes, backfire problem happens after accelleration when you let off the gas. I have an anti-afterburn valve on order (exspensive sucker) and should be in within a few days. Will let you all know if this solves the problem--from what I'm hearing, I just wasted a buck and a half. Have to get the Brat thru emissions within the next few weeks (pain) but if I get it to pass, I'm planning on sinking some bucks into this project--rust removal, paint, new exhaust, etc.
Sub friends--I cant get out of the parking lot without someone asking me if my Brat is for sale. What is it about this car that has captured the imagination? Maybe the fact that I have 230,000 miles and the EA 81 is still not burning one drop of oil!
Posted 09 November 2003 - 06:05 PM
but i took the 2 lines that come from the ASV's and hooked it into a tube that came outa the intake.. seemed to have fixed the backfire and the rough idle.. not sure what that line is for so dunno if it should be there or not.. going to dig in my FSM and figure it out..
Posted 09 November 2003 - 10:43 PM
Also - the quarters fit well in the ASV body itself, on the head side. You can just slip a quarter down past the threads, and then thread the pipe back on the valve - thus disabling the system without really removing it. Good if you want to pass emmisions later on, but don't want to fix a bad ASV right now, or fix exhaust problems. Really neato trick actually - Thanks Ken.
This one should go into the repair manual......
Posted 09 November 2003 - 11:39 PM
A guy down the street ran to my car telling me that I probably blew my engine up. I don't think I did, but I did blow the seam heck out of my muffler.
GD, maybe I can stop by sometime and you can show me how to do that quarter trick.
Posted 10 November 2003 - 12:04 AM
Posted 11 November 2003 - 06:18 PM
I do have another option--thank the Lord--my son lives in neighboring Clarke County, VA, and they dont require emissions test. I'm going to give him the Brat, get plates there, and stop worrying about it. Then I could put on a webber and forget the problems.
Thanks again for all the great advice
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