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1986Brat

86 Brat- Misfiring, low idle, stalls when stopped, awful MPG

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A few days ago, all of a sudden, I noticed a very low (400-600 rpm), shaky idling issue coupled with terrible gas mileage... Today it started stalling at every stop unless I give it gas.  I believe cylinders 2 and 4 are missing, though it's hard to tell because the idle is constantly fluctuating and randomly stalling.  When I get into gear the engine runs fine (still crappy MPG) and when the choke is on it runs fine.  I have new Bosch spark plugs and NGK wires replaced less than 200 miles ago.  New fuel filter.  Cleaned the crap out of the carb.  I pulled the plugs and they look normal.  Wires are certainly carrying a charge.  No random arcs.  No visible crack in distributer cap, terminals look fine.  Pretty sure there is no vacuum leak but I'm about to do a carburetor cleaner spray check.  Head gaskets look fine, no coolant leak or anything.

 

Could this be a problem with the ignition coil pack? I planned on picking up a better one anyways, hopefully tomorrow.

 

Could this be a thermostat issue? I flushed the radiator not long ago, I'm sure the current thermostat is 166,000 miles old.

 

PCV valve maybe?

 

What other checks/cleaning should I do before I go on a random part-buying rampage with money I don't have?? I certainly won't be driving this thing until I figure it out.  Thanks

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It is not the coil nor thermostat.

 

Since it is OK w/choke on,it is too lean for some reason.Probably a vacuum leak.

It would be worth giving the PCV a shake to make sure it is not frozen or just replace it.

 

I`d suspect the intake gasket on the 2/4 side first.Plenty of other possibilities though.

 

Forget random part-buying rampages.They are dumb and costly.

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Ignition coil/s can do funny intermittant  things when failing (break down under load)  so you've replaced all HT leads  coil/Distrubutor/spark plugs?  these can break down under load / when get warm also.

Could be a vacuum leak /hose/ inlet manifold gasket/s?

Does it have distributor with breaker points/condenser ?  these may need to replaced / regapped.

It definitely won't be the thermostat causing these problems.

Edited by subnz

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Hey sounds like the same problem I'm experiencing with my BRAT (EA71, though). 2 and 4 were definitely off compared to 1 and 3. My cylinder 2 was running very lean and I had corroded plug wires from moisture, most likely. I also have a very leaky fuel pump. I plan to fix those this weekend but also get under the valve covers and check the lash and do a compression check. I'll let you know if I find anything interesting on my side.

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Didn't have enough time this weekend to get under the valve covers, sorry. I spent too much time modifying the fuel pump I got to go in the stock location. I ran new plug wires, and did some compression checks on my "good" cylinders which are leaking. I really need to get in at the valves and look... But that will probably be more towards the new year now... will be travelling for the holidays. Anyway, good luck hope you find the problem.

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Thanks for the suggestions guys I've just gotten over the flu so I haven't solved the issue yet... I replaced the ignition coil which I've been meaning to do, it no longer stalls at stops but still idles low and messy. Power still sucks, mpg still sucks. I sprayed carb cleaner all over to find the possible vacuum leak, didn't notice any sort of rpm change. My progress on this vehicle is extremely slow due to my crappy schedule but I'll let you know when I figure it out.

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Best of luck figuring this issue out. Sounds somewhat similar, but worse than what I was z dealing with before I switched to the Weber. There are a bunch of vac lines to deal with on those Hitachi carbs. Let me just say that mine runs lots better and has more power with the Weber on.

I need to do something with that Hitachi thing now too which is what I'm guessing you have on your Brat.

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