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Guest Message by DevFuse
 

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carb problem, primary, after warm-up, bogs, fine if floored... [RESOLVED]


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8 replies to this topic

#1 Spiffy

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Posted 22 February 2006 - 09:15 PM

my '82 suddenly developed a stalling problem... after it warms up for about 5 minutes if I hit the gas it totally bogs down and stalls... I can get it to rev if I flutter the peddle a bit... and if I keep it floored it takes off fast, like the primary jet isn't cutting it and the secondary has to be kicked in for it to get enough gas...

I checked the float window and it's not filling up so I don't think it's flooding... I watched down the carb while I reved it and the jet seems to just be sputtering a little mist of gas in there...

what gives? it doesn't seem like the jet is clogged since it runs just fine for a few minutes until it warms up (even though it has a little hesitation that it already had before this problem)...

what's controlling the flow of gas that changes once it's warmed up?

it's a hitachi carb... and I'll probably just rebuild it this weekend but it'd be nice if I didn't have to... anybody know who sells a decent rebuild kit around here?

thanks!


--Spiffy

#2 GeneralDisorder

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Posted 22 February 2006 - 09:40 PM

Since it has to do with temp, your issue is partially choke related, or you have a vacuum leak that is opening with one of the thermo-vacuum valves.... but I would tend to suspect the choke.

Rev the engine to 2500 or so, and cover the intake with a rag till it almost dies (or does). This will cause massive vacuum in the carb and suck out any gunk clogging the jets. Repeat it a couple times.

GD

#3 Spiffy

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Posted 22 February 2006 - 10:50 PM

Since it has to do with temp, your issue is partially choke related, or you have a vacuum leak that is opening with one of the thermo-vacuum valves.... but I would tend to suspect the choke.


the choke is one of the first things I suspected but it isn't closing off the air or anything, I can watch down the barrel of the carb as I rev it and once the car wams up the choke is open...

what are these thermo-vacuum valves you're talking about?

Rev the engine to 2500 or so, and cover the intake with a rag till it almost dies (or does). This will cause massive vacuum in the carb and suck out any gunk clogging the jets. Repeat it a couple times.


hehe! I was totally going to do that... learned that trick from a friend in high-school that took a lot of auto shop classes...


--Spiffy

#4 GeneralDisorder

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Posted 22 February 2006 - 11:39 PM

I would say your problem is jet related - fluttering the pedal engages the accelerator pump repeatedly allowing you to rev the engine.... that alone points toward a fuel supply issue. The choke on the Hitachi keeps the idle higher before it pulls off, and the choke being parially closed helps add vacuum to the idle circuit.

The thermo-vac valves.... there should be two or three on an 82... some may be electric rather than thermo - on a timer. Hard to say without looking. Largely they are there for evacuating the evap canistor once the engine reaches operating temp, and other emmisions related BS. Personally I just remove all that junk. Knowing what it does, and how it works is a requirement to being able to effectively remove those types of systems without causing problems in the process.

GD

#5 Spiffy

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Posted 25 February 2006 - 12:42 AM

Rev the engine to 2500 or so, and cover the intake with a rag till it almost dies (or does). This will cause massive vacuum in the carb and suck out any gunk clogging the jets. Repeat it a couple times.
GD


I tried this a few times and it did help a bit... I didn't stall out nearly as often on my test drive around the neighborhood, probably driveable to work if I had to...

picked up the Echlin kit from napa this evening... (and a napa gold fuel filter...) going to rebuild this bad boy tomorrow...

weee!


--Spiffy

#6 GeneralDisorder

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Posted 25 February 2006 - 01:01 AM

Yeah - probably just dirty jets then. Very common on old Hitachi's. Not sure how that crap gets in there, but it sure is annoying.

GD

#7 dxrflyboy

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Posted 25 February 2006 - 07:55 AM

At the back of the carb base or on the intake just under it is a fairly large vacuum hose that connects to all the air suction gadgets. Pull the hose off and plug the port. Your car will probably run better than ever. If so, you can leave it that way or drive yourself crazy trying to fix the problem with the problem that was installed on your car at the factory.:banghead:

#8 civilpd

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Posted 25 February 2006 - 08:43 AM

I've read most of Haynes, Chilton, Factory, and some other one on the 87's while putting in my engine and I don't remember squat really. They do have some pretty good trouble shooting proceedures and I guess that is exactly what you are trying to avoid. But anyway, the temp sensor and all that stuff is interconnected and is a hoot to unscramble. In my 87 the trouble codes are accessed by plugging in some already in place plugs that are located under the plastic under the stearing column. Then, down on the computer itself, i guess, a little green light flashes. Pretty vague I know but maybe it will remind someone else who reads this and they can direct you better.

#9 Spiffy

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Posted 27 February 2006 - 10:15 PM

ok, the mystery is solved, sort of...

I rebuilt the carb with an Echlin kit from Napa... it didn't come with a diagram so I just winged it, and reference my Hayne's when needed...

there was a LOT of gunk in there... thick yellowish globs clogging everything...

you can see some pics here...

I had some o-rings left over that I couldn't find a place for... they don't go on my vent valve plunger as my Haynes diagram might suggest... *shrug*

I also have an entire sealed bag of parts left over that look like they're for a different style float needle and seat assembly...

put it back on the car and drove it around... once it warmed up it drove better than ever with no hesitation... I'm really getting my 72hp worth!

still need to look into why I have a crappy cold idle, but this is great for now...

now to work on the other million little things... :D (isn't that why we love these cars?!)

--Spiffy




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