Hitachi Feedback Carb Woes

[akojoian]

Howdy All,

Am havin' a bit of trouble with my '85 GL's Hitachi Carb or somethin'

I recently re-headed my EA82 and cured the broken-head-blowing-white-smoke

problem but now have problem with idle. Car starts and run excellent 'til

warm or sometimes longer then will idle rough then sometimes dies. Will start right fine: sometimes with bad idle, sometimes not. Spent hours searching the archives for clues. I know that the vac lines are in correct spots, dist. is firing and stable during poor idle, carb is definitely running lean (engine will pick up if carb throat is covered). Check fuel pump pressure and replaced filter. All solenoids/switches are functional. Tried un-corking tank thinking that it might be locking up: no problem there. If i disconnect the connectors to the duty sols., engine will run moderately better.

What gets me, is the fact that prior to the re-heading, i didn't have this problem. Also, under load, my GL has great power.

I noted while reading the archives that some recommemded NOT plugging ports on these feedback carbs. Any options there? I figured that by diableing the duty solenoids, I'm basically defeating any closed loop operation.

 

Unless a gremlin crawled into my float bowl while I had my intake off, I cannot figure what up/

I REALLY want to fix this porblem without Megasquirting/Weberizing/etc

 

Any help would be much appreciated.

 

Adam

Albany, Oregon

[Frank B]

Have you double checked the cam timing? Maybe, just maybe your a tooth off.

 

Or check the intake gaskets?

[85Sub4WD]

what he said and

timing,

choke adjustment - me thinks your choke is opening too far/too long

idle mixture adjustment - in center front of carb

idle speed adj - near linkage, screw faces you when looking head-on, make sure not to get it confused with the idle mixture adjust

both idle adjust screws should be adjusted w/ engine warm

[akojoian]

what he said and

timing,

choke adjustment - me thinks your choke is opening too far/too long

idle mixture adjustment - in center front of carb

idle speed adj - near linkage, screw faces you when looking head-on, make sure not to get it confused with the idle mixture adjust

both idle adjust screws should be adjusted w/ engine warm

 

 

Thanks, but as I said in my post, engine runs great warmed up, then suddenly idle goes to crap. Timing is dead on. Choke and idle speed havn't been messed with.

Cam timing is correct. Sprayed carb cleaner around base and intake gaskets to check for leaks - none. All ran great prior to head repair job. I'm starting to think that some debris got knocked loose in the float bowl. Carb always was "wet" until removal of intake and I drained fuel from carb by inverting intake/carb assy. Everything sat for a few months 'til I got a round tuit. Perhaps while "drying out", some sludge morphed into a chunk of port clogging (intermittently) ball of s**t?

 

I'll probably be removing carb and performing a rebuild.

 

Thanks again for input.

 

Adam

Albany, Oregon

 

'85 GL Wagon '96 Legacy Outback

[85Sub4WD]

All the symptoms you have are indicate a choke or idle adjustment problem, it would be a good idea to rule them out first - if you did anything with the engine (like removing the heads) that would affect what should be the proper adjustment. (it would remove the carbon from the combustion chambers)

 

The idle adjustment screw affects the idle ONLY when the engine is warm and at operating temp, hence why it (or your mixture adjustment) is probably your problem - they only affect your engine at normal operating temp. - at least try adjusting them before you do a rebuild, or removing the idle adjustment screw and squirting carb cleaner down into it

 

I have extensive expierence working with that carb, because up until recently, I had one on my car - they are tempermental, and a bit unpredictable.

 

A rebuild is very difficult on these carbs, I have rebuilt a variety of different carbs, and Hitachi's are the most difficult to do. You should avoid it if at all possible.

[TomRhere]

Not to cause you any great anxiety, but turning a carb up-side-down, is never a good idea.

 

Me thinks you may have gotten some yuck into one of the internal passages myself. You may be able to blast it out with some carb cleaner, may not. But I would atleast pull carb off engine, and try to blow some thru all passages.

[akojoian]

All the symptoms you have are indicate a choke or idle adjustment problem, it would be a good idea to rule them out first - if you did anything with the engine (like removing the heads) that would affect what should be the proper adjustment. (it would remove the carbon from the combustion chambers)

 

The idle adjustment screw affects the idle ONLY when the engine is warm and at operating temp, hence why it (or your mixture adjustment) is probably your problem - they only affect your engine at normal operating temp. - at least try adjusting them before you do a rebuild, or removing the idle adjustment screw and squirting carb cleaner down into it

 

I have extensive expierence working with that carb, because up until recently, I had one on my car - they are tempermental, and a bit unpredictable.

 

A rebuild is very difficult on these carbs, I have rebuilt a variety of different carbs, and Hitachi's are the most difficult to do. You should avoid it if at all possible.

 

 

Thanks for the input. Got 'er fixed.

The rebuild was a little tricky, but am experienced with carbs, throttle bodies, fuel injection. Prefer Q-Jets ;-) Not really hot on drivability issues with electronic carbs tho...

Lately fixed an '85 S10 2.8 V6. Same BS.

 

Again thanks!

Adam