waysrx7

A little background info. for ya. It's a stock 79' with a replaced engine from 81 or 82 (I'm assuming this since those are the years for the carburetor that was on it when I bought it). 81 or 82 carb. Checked for vacuum leaks - and I'm positve there are none (I have an 85 carb in it from the wreakers and runs fine, low idle). I have tried to rebuild this 83 carb a few times using the guides on this forum. It will idle below 1000 rpm's easy but hesitates to death if you press the gas pedal. It will run above the "death rpm's" of 1200 to 3000 rpm's but becomes somewhat erratic above 5500 rpm's. From this I believe I have a problem with the low speed circuitry. Question 1: do these carbs just wear out to the point of not being able to rebuild/clean them? Question 2: Will soaking the carb again (i have done this already) in carb cleaner, but for longer than a day and then using compressed air do anything more than the first time I did it? Sorry for the novel. This carb is getting the better half of me and I hate to throw something away that just needs someone to show it who's the boss.

trochoid

iTrader: (6)

When you soaked it in cleaner, recommend Berrymans, did you strip it all the way down and remove everything, including jets and air bleeds? Hesitation is often an accelerator pump problem. It's easy to reverse the diaphram. Also check for vacuum leaks, the amount of squirt you get from the ap jets and your fuel pressure.

If you have or haven't read through Sterling's writeups in the FAQs on the Nikkis, do so. You may have missed something in his troubleshooting suggestions.

waysrx7

So, I just spent 2 hours swaping carbs again and the accelerator pump works fine, but I still get a hesitation between 1000-2500ish rpms. I had it completely striped when I soaked it (everything that could come off, came off) and the sypmtom is that when I cruise in first with my foot barely on the gas (about 2000rpms) it hesitates. since I'm cruising it shouldn't be the accel. pump. And since it idles at 750 rpms (I like to keep it at 1000) I dont think I would have a vacuum leak. Any other Ideas?

Rx7carl

Is the choke fully open? And not to beat a dead horse but does the AP squirt immediately when the throttle is moved?

waysrx7

Choke is fully open. I think I adjusted the AP in half turns from as tight to as loose as it will go with the same hesitation at the same spot. And just to be clear, hypothetically - it doesn't matter if the AP works or not if you are just cruising because you are not increasing the throtle hense not squirting extra fuel. But yes I get a good squirt of fuel. Also, it hesitates the same when I bring it down from a stable 3-4000 rpms to about the 1500rpm mark. Thanks for the input though, I didn't think about the choke.

Sterling

Turning the AP nut IN increases the pump shot.
While working the linkage by hand and looking down the primaries, do you see a consistant and equal squirt from each AP nozzel? If the AP is adjusted to max shot and you are not seeing a healthy squirt, then something's wrong with your wieght & checkball installation.
Ordinarily i would say the "after 5500 rpm" problem is a fuel filter issue, but since you are able to swap out to a carb that does not die from fuel starvation after 5500 rpms, I suggest that the needle seat screens of the offending carb are clogged. Even if you recently rebuilt the carb with a new kit and had to remove & reinstall the screens, more crap could be clogging them. Remove the banjo bolt fuel rail and check the screens in there, as well.
... you do have a new fuel filter installed, yes?
And last but not least, be sure your float bowl vent solenoid is hooked up. Without it your carburetor cannot breathe and cannot function properly.

waysrx7

Float bowl vent solenoid is hooked up, already made that mistake once.
Two new fuel filters, one by the pump and one just before the carb.

I'll recheck the needle seat screens while I check the AP setup. But while I was rebulding the offending carb I took the fuel rail dohikki all apart and yes there was a lot of crap in there but I soaked it and blew it all out with compressed air so I am pretty sure it will be clean.

I do sometimes get fuel starvation at 6000rpms with the good carb but I suspect the pump is the culpret since I got the new filters.

AP, AP, AP. Since I keep hearing this I'm loosing confidence in my memory and will check it, the only problem I have is it takes me a couple hours to swap carbs and test grive and set idle and check for leaks and.... you get the point. I'm a student so my time is pretty limited here.
Thanks for the info.

Rx7carl

Make sure the float level is correct in the windows. If its low youll have all kinds of power problems from fuel starvation.