Signs of a bad carb

[MTSuby]

What are the typical signs that it's time to replace the Hitachi carb? I've got an '87 4wd wagon I'm curious about.

[Ginger48]

About the only things that ever go wrong with the Hitachi carb as long as you always use a good air filter is the

 

1. Electric choke (very seldom)

2. Accelerator pump (common but easy to replace)

3. Plastic oem float absorbs gasoline and gets heavy raising the fuel level in the bowl thus causing the engine to run rich. Easy to replace. Some parts stores carry brass replacement floats that last forever. (seldom a problem)

4. Inlet needle valve doesn't totally shut off the fuel from entering the bowl. Usually when this happens, excessive amounts of gasoline will flood the engine. This is easy to replace. (Seldom a problem)

[GeneralDisorder]

About the only things that ever go wrong with the Hitachi carb as long as you always use a good air filter is the

 

1. Electric choke (very seldom)

2. Accelerator pump (common but easy to replace)

3. Plastic oem float absorbs gasoline and gets heavy raising the fuel level in the bowl thus causing the engine to run rich. Easy to replace. Some parts stores carry brass replacement floats that last forever. (seldom a problem)

4. Inlet needle valve doesn't totally shut off the fuel from entering the bowl. Usually when this happens, excessive amounts of gasoline will flood the engine. This is easy to replace. (Seldom a problem)

 

Interesting assesment - comletely untrue, but interesting.

 

The Hitachi carbs (and there's quite a few models, each with it's own set of problems), suffer from a variety of ailments. Among them some of the above problems. But that's hardly a complete list.

 

In truth, no carb ever must be "replaced". They can be rebuilt, but in the case of the Hitachi's, and most especially the feedback Hitachi's and the DCZ series from the EA82's, it's often easier to replace the poor thing with a Weber. Coupled with the improved performance, ease of obtaining rebuild parts, and simple, rugged design, the Weber is a far superior and often cheaper when labor, and parts are considered.

 

GD

[Ginger48]

Interesting assesment - comletely untrue, but interesting.

 

The Hitachi carbs (and there's quite a few models, each with it's own set of problems), suffer from a variety of ailments. Among them some of the above problems. But that's hardly a complete list.

 

In truth, no carb ever must be "replaced". They can be rebuilt, but in the case of the Hitachi's, and most especially the feedback Hitachi's and the DCZ series from the EA82's, it's often easier to replace the poor thing with a Weber. Coupled with the improved performance, ease of obtaining rebuild parts, and simple, rugged design, the Weber is a far superior and often cheaper when labor, and parts are considered.

 

GD

 

 

GD, you remind me of what the naysayers were saying back in the 1960's and 1970's about the Rochester Quadrajet carburetor. Most performance minded people were talked (sold a bill of goods by the “experts”) into replacing their “complex” Q-Jet carbs with a simple easy to work on spread bore Holly carburetor. What is now well known now, 35-40 years later, the Quadrajet is one of the best carburetors ever built for dependability AND performance (yes, feedback and non feedback on them too). It is also now well known that Hollys are not dependable due to fuel leakage from around the fuel bowls and easily blown power valves.

 

The only time I’ve ever seen where the Hitachi's need a complete rebuild is when sour gas is left in them for an extended time, and this also applies to all carburetors and fuel injection also.

 

It’s been admitted many times here that the Weber does not give any more horsepower over the Hitachi, just better initial throttle response.

 

I’ve been working on Subaru’s for the last 27 years and wrenching for 44 years so I just MIGHT know what I’m talking about. No, I don’t post very much and I seldom visit this forum. I have more important things to do. Number of posts not length to time for being a member does NOT make an expert.

[GeneralDisorder]

GD, you remind me of what the naysayers were saying back in the 1960's and 1970's about the Rochester Quadrajet carburetor. Most performance minded people were talked (sold a bill of goods by the “experts”) into replacing their “complex” Q-Jet carbs with a simple easy to work on spread bore Holly carburetor. What is now well known now, 35-40 years later, the Quadrajet is one of the best carburetors ever built for dependability AND performance (yes, feedback and non feedback on them too). It is also now well known that Hollys are not dependable due to fuel leakage from around the fuel bowls and easily blown power valves..

 

This is not germain to the conversation in the slightest. Wasting the boards time with information on Rochester carbs from the 70's isn't helping anyone here, nor the original poster.

 

The only time I’ve ever seen where the Hitachi's need a complete rebuild is when sour gas is left in them for an extended time, and this also applies to all carburetors and fuel injection also.

 

It’s been admitted many times here that the Weber does not give any more horsepower over the Hitachi, just better initial throttle response.

 

Great - use the Hitachi. More Weber's and SPFI for me.

 

I’ve been working on Subaru’s for the last 27 years and wrenching for 44 years so I just MIGHT know what I’m talking about. No, I don’t post very much and I seldom visit this forum. I have more important things to do. Number of posts not length to time for being a member does NOT make an expert.

 

No, but reputation does. You aren't starting off well I might add. If you have more important things to do then why are you trolling here?

 

GD

[daeron]



I’ve been working on Subaru’s for the last 27 years and wrenching for 44 years so I just MIGHT know what I’m talking about. No, I don’t post very much and I seldom visit this forum. I have more important things to do. Number of posts not length to time for being a member does NOT make an expert.

 

 

Our good friend Rick was not attempting to puff his ego up, although his mannerisms certainly do seem like it.

 

Believe it or not, he is what he seems at face value: the type of person who has *probably* tried more than you (for whatever definition of the term "you" may be) and likely has at least some insight to the situation you are looking at. He will give you his honest and frank assessment, he puts his banner stating outright that he is an rump roast up there, and he presumes that you, as an individual, will be able to filter out any prejudices he had in his vision when he gave you his assessment of the situation.

 

In other words, just because what he said sounded like he was being pompous about things.. Doesnt mean he is actually being a jerk. Jerkhood lies in the motivations, and honestly, he is just being plain and blunt. No pains taken to be overly friendly, nor is anything dumbed down to any level but his own.

 

Now, this situation here arises simply because the man has very well known and deeply held feeling for the hitachi carburetors in question. While many have indeed had great experiences with these models, many many many more have found much solace in the simplicity and commonality of the Weber, just as those who had no clue how to tune a quadrajet were much more capable of utilizing the holley back in the sixties. The fact is plain and simple, that a weber carburetor is widely held one of the more reliable critters of mass production, whatever form it may take. The vast majority of the Hitachi fuel delivery systems were either straight copies of European designs (Datsun "SU" carburetors) or developed from such licensed products, and despite the various successes they had in duplicating others designs, there were regrettably also weeds in the crop.

 

You could run with weeds, or you could have uber-mutated genetically Superior Ultra-Corn!

 

(had to insert lame joke to lighten tone)

 

Anyhow, my point to you, ginger, was that it really isn't worth it to get mad at GD for the way he acts. In time, it becomes evident that he only behaves like an rump roast; really, he's really smart, got great methodologies, and is extremely helpful, even when people specifically request that he abstain from answering on a topic In short, one of the more valuable members of the forum. So, in the meantime.. It doesn't do any good to fight him. That just makes it more fun for him

 

Now if only decibels and kilobaud weren't being wasted on voices of less wisdom..... (NOT "pointed" at any member currently present in this thread)

[MTSuby]

That was exciting. And well said.

 

Anyway, what I'm getting at is: poor fuel economy? Hesitation? Stalling? I understand that there are probably also 20 other things that can cause similar symptoms, but, for someone who doesn't necessarily know what his car will run like if it's running rich, or doesn't feel comfortable taking a look to see if floats etc. are bad, what symptoms will get you thinking "carb"?

 

I can replace most things with the help of you on this site if I know they are bad, but diagnostics & exploratory mechanicing are not my strong points.

 

Thanks!

[Subarule]

That was exciting. And well said.

 

Anyway, what I'm getting at is: poor fuel economy? Hesitation? Stalling? I understand that there are probably also 20 other things that can cause similar symptoms, but, for someone who doesn't necessarily know what his car will run like if it's running rich, or doesn't feel comfortable taking a look to see if floats etc. are bad, what symptoms will get you thinking "carb"?

 

I can replace most things with the help of you on this site if I know they are bad, but diagnostics & exploratory mechanicing are not my strong points.

 

Thanks!

 

The symptoms you list could very well pertain to vacuum leaks instead of the carburetor. I had the very same ones for a long time with my Hitachi-carbed '86 GL 4X4 5-speed wagon. I had to take it into the shop recently for something else and asked my mechanic to look for vacuum leaks. Two were found and repaired. The car has run amazing since then. I am still doing a mpg check but I can already tell that I've gained at least an additional 8 mpg (haven't made much of a dent in my full tank of gas during strictly in-town driving). I'm trying to get down to at least a 1/2 tank before refilling in order to get a more accurate read.

 

I still have a wee vacuum leak, I think, but I can live with it until some other work has to be done under the hood and I'll have it looked into then.

 

Meanwhile, my car seems to have a new lease on life.

 

Subarule

[MTSuby]

Interesting....see I know I have a vacuum leak...that would be why I hear a hissing noise when I push in the heater control buttons, right? And feel a pretty serious loss of power, especially when I'm using the defrost setting. I looked around and couldn't find the leak, but maye I should have a mechanic locate it.

[daeron]

The switch in the dashboard that controls AC mode selection is a vacuum switch, and there are five or six lines hooked up to the back IIRC; one input and one for each position. If you start taking the gauge shroud apart (it isnt THAT major to figure out, and I can't recall specifics to walk you thru it) then either the leak should make itself apparent, or what minimal further disassembly you might need to do would be obvious.

 

Getting your HANDS in there to slip the lines on, might not be as simple as figuring out how to pull it apart.. but its usually agreed upon that re assembly is truly the biggest PITA; regardless, it isn't THAT big of a deal. (says the lad who still hasn't gotten around to replacing his busted AC switch because, well, thats too much of a PITA right now :-p) I WILL say that my adventures in the top part of the dashboard were nowhere NEAR the nightmare that replacing the @#^$%#$ing turn signal blinker was.... THAT took me four or five hours, without a doubt the most difficult repair I have had to make on the car thus far.

 

However, if you want to eliminate the leak to evaluate how the car will run (IE, "is this the whole problem?") then you could simply remove the vacuum line going from the engine to the canister at the rear passenger side of the engine bay, and pinch it off. Then, no vacuum is being lost in the AC controls whatsoever, and any running issue you still have will NOT be solved by dickering with the AC switch.

 

In other words, pinch that vacuum supply line, and you have normality; anything you still cannot cope with is thenceforth your own problem.

[GeneralDisorder]

See if you can locate where the "sound" of the leak is loudest. Other members have found leaks at the vacuum actuators or in rotten lines near them. It could be at the switches as it happens in more than just one posistion, but each button switches vacuum to multiple actuators so it may be that it does leak in multiple positions simply because those positions all supply vacuum to the leak.... yeah

 

Anyway, yes a vacuum leak can severely affect low-rpm and idle quality.

 

If you don't have one, you might invest in a cheap vacuum guage and read a bit on how to decipher the readings from it. It can tell you a lot about the tune of your engine and would reveal if you likely have any vacuum leaks or not.

 

Also spraying around with a bit of carb cleaner will locate vacuum leaks - when the cleaner is sucked into the leak it will increase the mixture and cause the engine to speed up momentarily.

 

GD

[Subarule]

Interesting....see I know I have a vacuum leak...that would be why I hear a hissing noise when I push in the heater control buttons, right? And feel a pretty serious loss of power, ...

 

I had the same thing, including when I ran the AC.

 

It wasn't my only vacuum leak, but it was one that was siphoning away power. When I'd use anything on the HVAC panel I'd hear a sucking noise when I activated it.

 

Every vacuum hose should be replaced with new, in my opinion. If you can do that yourself, all the better. That way you know you're starting out with good hoses and good connections and the hassle of trying to trace out every leak is eliminated. One leak or some leaks may be so small that they're almost impossible to locate, but they all add up.

 

Subarule

[Gloyale]

I had the same thing, including when I ran the AC.

 

It wasn't my only vacuum leak, but it was one that was siphoning away power. When I'd use anything on the HVAC panel I'd hear a sucking noise when I activated it.

 

Every vacuum hose should be replaced with new, in my opinion. If you can do that yourself, all the better. That way you know you're starting out with good hoses and good connections and the hassle of trying to trace out every leak is eliminated. One leak or some leaks may be so small that they're almost impossible to locate, but they all add up.

 

Subarule

 

A momentary sucking sound when switching HVAC controls is nnormal. It is only if you hear a continual hiss that there is a leak.

 

I agree that every vac hose on a 20 year old car should be replaced. BUT.....make sure to check the diagrahms, and in the hoses themselves for "orifice" plugs. They are little metal pellets in the vaccum lines, that resrtict, or meter the vacuum to certain parts of the system. They must be pulled form the old vac line and inserted into the new hose.

[MTSuby]

Ok, I do only hear a momentary hiss, but I also feel a loss of power, especially when I use the defrost, so I'll check it out. Thanks!

[GeneralDisorder]

Ok, I do only hear a momentary hiss, but I also feel a loss of power, especially when I use the defrost, so I'll check it out. Thanks!

 

Momentary hiss is perfectly normal

 

Loss of power is also normal as most of the settings (defrost especially) run the AC compressor.

 

GD

[MTSuby]

Momentary hiss is perfectly normal

 

Loss of power is also normal as most of the settings (defrost especially) run the AC compressor.

 

GD

 

Awh man, that means this may not fix my no-power issue? Worst when it's cold, I'll accelerate from a stop and it'll just cut out..gets all bogged down & stumbly, then gets over it. Well, I'll still look for a leak and see what I find.

[Gloyale]

Awh man, that means this may not fix my no-power issue? Worst when it's cold, I'll accelerate from a stop and it'll just cut out..gets all bogged down & stumbly, then gets over it. Well, I'll still look for a leak and see what I find.

 

Accelerator pump on the carb? easy to replace without rebuilding the whole damn thing.

[MTSuby]

Thanks. I'll keep checking things out.

[GeneralDisorder]

Awh man, that means this may not fix my no-power issue? Worst when it's cold, I'll accelerate from a stop and it'll just cut out..gets all bogged down & stumbly, then gets over it. Well, I'll still look for a leak and see what I find.

 

Is your AC idle-up vacuum pot working as designed? The idle with the AC compressor engaged is generally around 1200 RPM or so, but it's adjustable.

 

GD

[MTSuby]

Is your AC idle-up vacuum pot working as designed? The idle with the AC compressor engaged is generally around 1200 RPM or so, but it's adjustable.

 

GD

 

 

Oh boy! All sorts of things to check. I have no idea, but if nothing else, I'll start making a list of things I want a mechanic to check, if I get lazy..

[85T-REX]

You should difinately check the acc. pump first. Just look down the carb, past the choke plate, you should see a small tube sticking out from the float bowl side in front of the primary venturi. This is where the fuel comes from the acc. pump. When you open the throttle, you should see fuel spraying into the carb. (Best to do this with the engine off.)

 

If no feul, that's your problem. It's an easy fix unless the pump cylinder wall needs honed. It's a little tricky but basically loosen the top of the carb and carefully lift it up, while being careful not to damage the gasket, until you can get the acc. pump shaft out. There will be a spring under it holding a small ball at the bottom. Check those and replace if you have them. (As in a rebuild kit.) Then put the new acc. pump shaft in and set the carb top back down and hook it all back up and you should be good to go.

 

I did that to my wagon a couple years ago and it's still running great.

[MTSuby]

Ok, I feel comfortable checking that.