Spiffy Posted January 27, 2007 Share Posted January 27, 2007 ok, I've stared at this thing for a while now and can't figure it out... I have a few carb problems here and everything looks like it's working, but it's just not doing what it's supposed to... cold idle: it sucks... stalls and doesn't bump up to the fast idle at all... I looked at the cam in the choke assembly and it doesn't seem like it could ever work... there's nothing in the linkage that connects to the cam... is the spring supposed to do more than kick it back to it's stop? I can move it around manually and get it to kick on the first notch, but that's it before the choke lever gets in the way... hesitation: after it warms up and the choke is open it hesitates when I first hit the gas... I think it's getting too much air because I can close the choke most of the way manually and then rev it up without the hesitation... tried messing with the mixture screw (?) at the bottom front of the carb but that didn't seem to help much... (what's that supposed to be adjusted to anyways? like 5 screws out?) so, where to I go from here? I can take pics of everything if needed... --Spiffy Quote Link to comment Share on other sites More sharing options...
goobaroo Posted January 27, 2007 Share Posted January 27, 2007 the mixture screw is only for idle. adjusting it changes only the idle mixture and has no effect on the mixture at any other throttle position. try adjusting this after your car warms up and it might help your cold idle problems. just what i know, hope it helps! Quote Link to comment Share on other sites More sharing options...
[HTi]Dain Posted January 28, 2007 Share Posted January 28, 2007 Basically sounds like the typical "Hi-crappy" carb to me! When I would first fire up my car, I would have to hold the throttle open (for about 1-2minutes) at about 2000RPM to keep it alive, and get it warmed up, then the high idle would keep from there. About the hesitation, mine started doing that... I figured out it was the secondary jet leaking, at idle, and at highway speeds (for some damn unknown reason) and that was even after a rebuild. So you might want to check that. I would suggest to rebuild the carb. (cheapest option compared to a Weber conversion) get it all cleaned up inside (outside too). Also, some "bandaids" to try would be to turn up the idle speed, and mixture... Quote Link to comment Share on other sites More sharing options...
Spiffy Posted January 28, 2007 Author Share Posted January 28, 2007 I already did a rebuild on it several months ago because it barely ran at all... now I just have this cold idle (fast idle) and hesitation when warm problem... the hesitation is only when it's warm... I can press the gas down when it's cold and it revs right up... but once it warms up and the choke opens when I hit the gas it sounds like it's starting to die, stumbles, and then starts to rev... I can hold the choke closed most of the way with my finger and then give it gas and it doesn't hesitate... so I'm thinking it's getting too much air or something and needs to be a little choked the whole time, but that just doesn't make sense... not sure what do adjust to get rid of the stumble... --Spiffy Quote Link to comment Share on other sites More sharing options...
hatchsub Posted January 28, 2007 Share Posted January 28, 2007 Could it be that its set too lean? The choke is supposed to enrich the mixture so if its running good with the choke on and hessitating when its off maybe the mixture is set too lean. Pull a spark plug to check the color. As for the no fast idle..there is an adjustment for the fast idle cam. Im not exactly sure how to do it anymore but it involves bending a piece of linkage on the passenger side of the carb. You might also want to check the entire motor for vacuum leaks. I had intake leaks and vacuum hoses that were bad on my old subaru. Just my 2 cents. Ive never really tried to do much with my hitachi as it seems to be doing ok. Quote Link to comment Share on other sites More sharing options...
[HTi]Savage Posted January 28, 2007 Share Posted January 28, 2007 Ur fast idle cam is all fubared. Are u sure that when u rebuilt the carb u got the float level right. U might want to check that. U can take the top of the carb apart and check it pretty easly. Run the motor and look in the carb. look in the secondary barrel, see if there is fuel dribbling out of the secondary jet. observe how the fuel sprays out. should have healthy spray. no dribbling. Start there and let us know what u see. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 28, 2007 Share Posted January 28, 2007 Are you 100% sure you didn't lose the accelerator pump check valve ball? It's a tiny little plastic guy about 1/8" in diameter. If you didn't get that in, or the got the pump spring in upside down, the accelerator pump will not function and you will get the slight hesitation when warm like that. As for the fast idle - that's all done with the linkage and the choke setting. It took me about 7 to 10 try's to get to a point where I could rebuild a Hitachi and have all the bits work as designed - especially the fast idle/choke mechanism. Weber, or SPFI swap is the prefered "fix" for all Hitachi related problems. GD Quote Link to comment Share on other sites More sharing options...
Spiffy Posted January 29, 2007 Author Share Posted January 29, 2007 Savage']Ur fast idle cam is all fubared. Are u sure that when u rebuilt the carb u got the float level right. U might want to check that. U can take the top of the carb apart and check it pretty easly. Run the motor and look in the carb. look in the secondary barrel' date=' see if there is fuel dribbling out of the secondary jet. observe how the fuel sprays out. should have healthy spray. no dribbling. Start there and let us know what u see.[/quote'] yeah, the fast idle cam does seem pretty useless at this point... maybe I can rig another spring in there... but it looked in-tact... time to climb inside the hood... yeah, guess I can check the float... I know the spray is a lot stronger than it was before I took it apart... at least in the primary... --Spiffy Quote Link to comment Share on other sites More sharing options...
Spiffy Posted January 29, 2007 Author Share Posted January 29, 2007 Are you 100% sure you didn't lose the accelerator pump check valve ball? It's a tiny little plastic guy about 1/8" in diameter. If you didn't get that in, or the got the pump spring in upside down, the accelerator pump will not function and you will get the slight hesitation when warm like that. I'm sure the ball is in there, but I didn't remember the spring being unidirectional... hmmm... well, guess I'll have to take the top off and make sure those bits are good then... it seems like an accelerator pump issue, but everything looks like it should be working... Weber, or SPFI swap is the prefered "fix" for all Hitachi related problems. yeah, this hitachi is on its last life... I'm just trying to limp it along until I can get a weber on there... or an ea82 spfi parts car to do some swaps from... --Spiffy Quote Link to comment Share on other sites More sharing options...
Spiffy Posted February 8, 2007 Author Share Posted February 8, 2007 ok, I checked out the accelerator pump and the float level... the accelerator pump seems the be in good working order... it shot plenty of gas when I was checking it out and the lever seems to be moving it down enough for a quick squirt... little ball in the bottom, spring, valve, rubber boot on carb top... I need to check in more light to make sure it's squirting enough and it getting there fast enough... the float level was bordering on too low... I adjusted it to bordering on too high... my bad... but that resolves my stuttering around sharp right corners problem... I've got to get back to the float level and put it dead on the dot, but I didn't have time then to do it again... here's a 1.3mb mpg movie of me reving the car and it hesitating: ... and the cold idle seems totally borked... here's a picture of inside the choke at idle with no throttle: here's a picture of inside the choke at full throttle: the little J20 fast idle cam never moves... in fact, there's a spring on it that keeps it nicely sitting against that little stop by the bent end... what's supposed to move it? if I manually spin it around the highest cam setting it will spin to is 1... --Spiffy Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted February 8, 2007 Share Posted February 8, 2007 The cam is only engaged when the choke spring is holding the choke plate closed. Hesitation could be idle speed, timing, vacuum leaks, etc. And vacuum leaks near the base of the carb will cause hesitation. Do you have the vacuum advance attached to the carb? Does it work? GD Quote Link to comment Share on other sites More sharing options...
[HTi]Dain Posted February 8, 2007 Share Posted February 8, 2007 Yeah, my Hitachi was a pain to get tightened down at the base. I needed to retourqe the nuts several hundred miles later. You might want to check that, eh. Quote Link to comment Share on other sites More sharing options...
Spiffy Posted February 9, 2007 Author Share Posted February 9, 2007 The cam is only engaged when the choke spring is holding the choke plate closed. Hesitation could be idle speed, timing, vacuum leaks, etc. And vacuum leaks near the base of the carb will cause hesitation. Do you have the vacuum advance attached to the carb? Does it work? even with the choke close there doesn't seem to be any mechanism that can get the fast idle cam to spin around... I'm totally baffled... I'm sure that there's a vacuum leak since I've got a lot of play in the throttle shaft, and I verified the leak with some carb cleaner spraying in the area... which is why this carb is on its way out... just trying to get it as close to good as I can until I can afford to put a weber on there... pretty sure the vacuum advance is working... no bogging once I get past the initial pedal press hesitation... but I haven't tested it to see how well it's working... I may just level the float and call it good, er, as good as it will get... but the fast idle cam still baffles me... I can take a couple more pics with the choke closed if that will help... and with the idle cam spun around onto the 1 mark... --Spiffy Quote Link to comment Share on other sites More sharing options...
Spiffy Posted February 9, 2007 Author Share Posted February 9, 2007 Dain']Yeah' date=' my Hitachi was a pain to get tightened down at the base. I needed to retourqe the nuts several hundred miles later. You might want to check that, eh.[/quote'] actually, I saw that in another carb hesitation thread, and I did tighten them a bit more since they weren't THAT snug... but I didn't want to really wrench them down too hard... and it's not like there's a lot of room for a torque wrench, and it's probably inch-pounds, which I don't have... --Spiffy Quote Link to comment Share on other sites More sharing options...
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