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Subaru Loyale Hitachi carb screws and emissions

Hitachi 2bbl Colortune emissions

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17 replies to this topic

#1 Tremmor

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Posted 12 December 2013 - 03:00 AM

Hi!
My Subaru Loyale stw, 1987, 4x4, 1.8L with Hitachi 2 bbl carb didn't pass inspection, inspector said it was running too rich. I had rebuild carb partually earlier, replaced accelerator pump and gaskets and cleaned it with carb cleaner, after that flat spot was gone. Ignition timing is set to 8 degrees BTDC distributor vacuum line plugged and engine warm at ~700 rpms.

I found Gunson Colourtune and decided to give it a try before having a mechanic to check emissions and possibly adjust carb with proper equipment. It was harder to see color differences in spark in RL than in Youtube videos, first it was strong yellowish spark and after fidding with air/fuel mixture screw it was harder and harder to see, resulting a small spot to see spark but too small to see actual color. I removed Colortune Plug as I thought it was in need of cleaning but it wasnt the case, it was just like new. I'm going to give it another try and change spark plug wires and try maybe other cylinder to see if that results stronger spark.

Should I increase rpms with idle mixture screw so spark is easier to see and adjust it back to 700 rpms when done playing with air/fuel mixture or do they interact and need to be adjusted in turn? Am I just making this too difficult myself instead of dialing in initial setting for air/fuel screw, if there is such, please share =)


 



#2 ruparts

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Posted 12 December 2013 - 10:55 AM

hi,

  have you replaced the oxygen sensor?  that is an important part of the emission management and fairly cheap about 20-25 dollars US.  when they are not working they usually drive the ecm to a rich condition rather than a lean one since that would lead to engine damage.   it's mounted in the exhaust Y pipe where the two sides join together , a single wire type.  they do make a difference if not functioning. 



#3 Tremmor

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Posted 12 December 2013 - 11:11 AM

update: found a vacuum leak at the base of carb  where a phenol-plate (?) is sandwitched between carb and intake manifold. I had used two paper gaskets there with gasket glue but maybe i should be more liberal with applying glue and wait good time to make sure glue is set before starting engine.



#4 Tremmor

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Posted 12 December 2013 - 11:19 AM

hi,

  have you replaced the oxygen sensor?  that is an important part of the emission management and fairly cheap about 20-25 dollars US.  when they are not working they usually drive the ecm to a rich condition rather than a lean one since that would lead to engine damage.   it's mounted in the exhaust Y pipe where the two sides join together , a single wire type.  they do make a difference if not functioning. 

Excellent, gonna test it. =)



#5 robm

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Posted 12 December 2013 - 11:36 AM

Does it even have an oxygen sensor?  Euro spec car with a Hitachi 2 bbl may just have a simple carb, no feedback, no ECM.

 

One thing to try is to increase your idle to 900 RPM, adjust the mix for best idle (highest), bring it back to 900 with the throttle stop adjustment, then reduce the idle speed to 700 by making it run leaner with the mixture screw.  I am not sure how the Colourtune would work in this situation, whether it would be of use or not.  This was the tuning method used by some vehicles with similar carbs to that one, back in the day.

 

I am surprised that a carb with a vacuum leak would run rich. Is this emission test run just at idle, or is it run at speed as well, on some kind of wheel dynomometer?

 

The phenolic plate is a heat insulator, so the carb doesn't ge too warm.

 

Good luck.



#6 Tremmor

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Posted 12 December 2013 - 02:46 PM

Emission test was at idle, I found report:

CO%:5,24 (3,5 is limit)

CO2:12,1

HC ppm 350 (600 limit)

O2:0,47



#7 robm

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Posted 13 December 2013 - 12:24 PM

http://www.crypton.c... emissions.html

 

Good stuff on emissions tuning.

 

It would seem you do have a rich condition, despite the vacuum leak.  Fix it, then either tune lean, as I suggested, or tune for best idle, and see what happens.  If you can get a emission tester on it before you go into the test station, all the better!

 

Do they sell bottles of magic liquid that guarantee passing emissions tests in Finland?  They usually have some kind of oxygenated fuel in them.  It might work in this case.



#8 ferox

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Posted 13 December 2013 - 02:11 PM

Does your carb have a sight glass on the side of the bowl?  If more tuning doesn't bring the emissions to regulatory spec. you might check your float level and power valve in the bowl.  Check the power valve washer to make sure it's intact.  Clean the power valve with carb cleaner.  I usually use a piece of guitar string to carefully ream the tiny port on the side of the valve.  Sometimes the power valve plunger gets a little bound as well.  If this is the case, clean it with carb cleaner and push the plunger in and out by hand to work out any debris.  It will probably take a few cleanings like this, but you will likely feel it start to plunge more smoothly.  Then give it a light lube with some light petroleum based lube like wd-40.  Don't use silicon or penetrating oil.  Even if this is not your problem it can only help.

 

I am not as familiar with ea82 Hitachis so disregard my descriptions if they don't match your Euro spec carb.



#9 naru

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Posted 14 December 2013 - 03:48 AM

Sight glass = first thing to check

Had one last week that was too low.Adjustment gave tremendously improved drivability.

 

If the fuel level is too high,idle mixture will be richer.

It is difficult to reconcile your rich idle with a vacuum leak unless the float level is too high or the idle air bleed passages are restricted.

 

You might try disconecting the charcoal cannister(if so equipped) in case it is somehow adding gasoline vapour at idle.

 

Gasket Goo around carbs never works,in my experience.

Make yourself some thicker gaskets.



#10 Tremmor

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Posted 14 December 2013 - 11:08 AM

Unfortunately no glass in carb.

 

Ferox, do you mean by power valve plunger acceleration pump? Previous carb had rubber plunger and rebuild kit had leather one so I replaced it since rubber plunger had shrunk.

 

Naru, I'm pretty sure that the cleaned, second hand carb wasnt fiddled before me since there was no witness marks at screw heads, so I'm tempted to believe that fuel level float aint bent. Unless it needs to be adjusted because of wear and stuff. Both carbs had about 200k km, its about 125k miles.

 

Made two paper gaskets and smeared Plastic Padding Gasket goo to improve sealing since phenol plate has scratches caused by enthuasist diy'er =) Checked carb to manifold nut torques from Haynes manual and I'm starting to think that I hadnt tightened those earlier tight enough. Tested that 16 ft-lbs (about 20 Nm) in vise to have feel for open wrench operation. Its now much tighter than ealier. Gonna test tomorrow =)



#11 naru

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Posted 14 December 2013 - 01:05 PM

Not Hitachi? What kind?

 

I don`t know how they go out of adjustment with out fiddling,but,they do.



#12 Tremmor

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Posted 14 December 2013 - 02:05 PM

Its Hitachi allright but not with glass.

 

http://oi42.tinypic.com/29g0if6.jpg



#13 ferox

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Posted 14 December 2013 - 02:27 PM

Unfortunately no glass in carb.

 

Ferox, do you mean by power valve plunger acceleration pump? Previous carb had rubber plunger and rebuild kit had leather one so I replaced it since rubber plunger had shrunk.

 

Naru, I'm pretty sure that the cleaned, second hand carb wasnt fiddled before me since there was no witness marks at screw heads, so I'm tempted to believe that fuel level float aint bent. Unless it needs to be adjusted because of wear and stuff. Both carbs had about 200k km, its about 125k miles.

 

Made two paper gaskets and smeared Plastic Padding Gasket goo to improve sealing since phenol plate has scratches caused by enthuasist diy'er =) Checked carb to manifold nut torques from Haynes manual and I'm starting to think that I hadnt tightened those earlier tight enough. Tested that 16 ft-lbs (about 20 Nm) in vise to have feel for open wrench operation. Its now much tighter than ealier. Gonna test tomorrow =)

 

Ok, well if there is no sight glass on the side of the bowl, then you need to pull the top of the carb off and check the float level.  Like Naru says, it seems somewhat inconceivable that the float would go out of adjustment but they do and not only that but they can get way out of adjustment.  You have to pay close attention to what position the float closes the needle valve because the needle is spring loaded, so the valve will close before the float is out of travel.  Also check to make sure your main jets are fully seated and the washers are in good condition.

 

The power valve (if present) is located on a little bench in the float bowl kind of between the two main jets.  The plunger is metal with a spring and is staked into the top of the carb, so it's not removable.  I have recently seen Euro spec Justy carbs for the EF10 engine that did not have a power valve.  The Justy shares the same carb base as the Loyale.  The picture in the link you provided actually looks like one of those Justy carbs.

 

The only sealant I use on carb gaskets is called Gasgacinch.  It's made for carb gaskets and is allowed to dry on the gasket before installation.  Not sure how available it is in Finland.  I also cut my own gaskets out of high quality gasket material.  If I did not have access to gasgacinch, I would not use a sealant at all, but that is only true for use with high quality gasket material.

 

http://www.gasgacinc...gacinch_002.htm

 

http://www.ebay.com/...4057980?lpid=82



#14 Tremmor

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Posted 15 December 2013 - 01:55 PM

Started engine and carb base didnt leak so far so I continued as Robm suggested, increased rpms to 900 and Colortune spark was much easier to see, but turning mixture screw all the way in didn't make engine shutdown. Does this count as symptom for carb float being out of adjust?

 

Oh, and when i tried to adjust rpms back to 700's noticed that they intermittently dropped to 550 and after a few secs they climbed back. I turned a bit more idle screw to raise rmps and then fan kicked in and with that rpms were 1100 just like that.

 

Adjusted idle back to 700 and soon it was acting up again, I thought it wasnt running sometimes on all cylinders so I started removing spark plug wires, honestly didnt notice any difference except when I got zapped in my finger, luckily i had rubber gloves on. Then I opened distributor cap and there was carbon buildup as well as in rotor, removed it with sandpaper and started engine. Cap and rotor were replaced like 100 miles ago as well as coil. Steady 700 rpms, very smooth. Yep, turned engine off, bolted air filter back and started again only to see engine sputter and die under minute. 

I'm starting to think there are numerous issues in this car =)

 

Pics of the old carb, the plunger was sticking in this one as Ferox posted, when I pressed it in all the way in and removed finger it took 1 or 2 secs to bounce back but WD40 did wonders =) Gonna test same thing with carb in use and see if I can set float as well.


hitachi carb float
http://oi41.tinypic.com/2nlad5y.jpg

hitachi carb plunger
http://oi40.tinypic.com/ejinuu.jpg

 

distributor cap
http://oi40.tinypic.com/n5imw.jpg



#15 Tremmor

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Posted 15 December 2013 - 03:22 PM

Thanks to Xman for his thread, his link has float adjustment specs I was looking for some time, as well as other good stuff for Subaru ff-1/1300/1400/1600/1800/Brat 1970-1984

 

http://www.ultimates...rb-float-level/



#16 naru

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Posted 16 December 2013 - 09:03 AM

Started engine and carb base didnt leak so far so I continued as Robm suggested, increased rpms to 900 and Colortune spark was much easier to see, but turning mixture screw all the way in didn't make engine shutdown. Does this count as symptom for carb float being out of adjust?

 

No,not really.

It means the throttle is open too far and the engine is not running on the idle circuit.Fuel is being pulled from the main circuit instead.

Could be because the idle jet or air passages are plugged,Anti diesel solenoid inoperative too,

 

200 rpm is way too much rpm drop w/doing a lean drop adjustment.More like 30-50rpm.



#17 robm

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Posted 16 December 2013 - 11:55 AM

You are right.  50 RPM is more like it.  It has been a long time since I had to do this.

 

The best thing to do is to get it running right and reliably, then lean it out a bit to get it through the test.



#18 Tremmor

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Posted 16 December 2013 - 11:56 AM

Took carb top out and verified no crap in fuel bowl and all jets were tightly seated. Oiled plunger but it wasnt sticking as bad as old one. Compared float and needle adjustments to old carb and noticed that current needle spring didnt return fully like old one. The clearance between float tab to needle blunt end was like 3/64" (about 1.2mm) when needle was lightly seated, the old carb had 0.0079 inches (0.2mm) and the one I found in rebuild kit didnt have any play when tested with old float.

 

Unfortunately Autozone site didn't work too well with mobile phone connection so I couln't verify correct way to set things, so I took my changes with new needle and no clearance setting. And guess what... It worked, smooth idle, very little variation in rpms and the Colortune plug color was strong bright blue. Dunno how it behaves when I actually drive the car but I have high hopes.

 

 

You guys are awesome, thank you so much! Couldn't solve this without your help! :)

 

 

Carb needles comparison, from left to right: needle I was using with broken spring, old needle, repair kit needle
http://oi39.tinypic.com/jsypzd.jpg

Float and needle, needle lightly seated, float tab clearance
http://oi41.tinypic.com/b6u0xx.jpg







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