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Rebuilt the carb, now I'm getting no fuel to the bowls

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Old 08-07-08, 08:04 PM
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TN Rebuilt the carb, now I'm getting no fuel to the bowls

The car is an 85 GSL, all stock. I've been living with a nasty low RPM hesitation for quite awhile now, so I finally decided to give the carb a rebuild. Other than the hesitation, the car ran very well. After a few minutes of trying to remove the carb, I decided the rats nest needed to go. So I removed the rats nest and rebuilt the carb. Everything went pretty smoothly. I'm pretty sure I have everything hooked up correctly, and anything I couldn't find a source for I capped off.

So after some pumps of the gas and a little cranking, it fired up and idled pretty smooth at 750 for about 10 seconds. At that point I noticed there was fuel spraying out of one of the banjo bolts that I forgot to torque down. Oops! So I shut it off and fixed that. Now it will start up if I pump the gas a bunch of times first, but it will only idle for about 5 seconds. More or less depending on how many times I pumped the gas. If I just crank it dry, it will fire up after about 5 seconds but die right off the bat.

The front bowl is empty. I'm positive on that one, as I cleaned up the sight glasses during the rebuild and I shined a flashlight in there. I know I've got fuel pressure to the carb (thanks to the aforementioned gas fountain) and the screens on the banjo bolts are clean and it good shape. I also made sure I didn't mess with the float levels during the rebuild, and they both looked evenly level when I put it all back together.

So any of you Nikki carb gurus have an idea why my bowls aren't filling up? I've tried beating it with a hammer and I'm pretty much out of options here! Any help or suggestions at all would be appreciated.
Old 08-08-08, 04:56 AM
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Sounds like the float might be hung up. Pull the top of the carb back off and see what's going on it there.
Old 08-08-08, 08:23 AM
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I should have said "any suggestions other than 'pull it back apart' would be appreciated." I'll give that a shot later today. I really am tired of fooling with this thing!
Old 08-08-08, 10:18 AM
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lol. Just pulling the top off the carb isn't too bad. You don't need to remove the carb from the motor anyway. I would have suggested banging on the top of the carb to knock the float loose, but you mentioned that you had already tried that.

Alternatively, you might be able to remove the brass bolt by the sight window and reach in through there to see how the float moves....
Old 08-08-08, 10:21 AM
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I say pull the top off and work the floats up and down a bit. I had to do that with my Sterling when I first got it on the car. Only took a few minutes.
Old 08-08-08, 01:13 PM
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Alright, well I pulled the top off. The rear bowl was half-empty (I'm a pessimist at this point). The front had gas in there, but it was barely covering the bottom. Think the level could be out of adjustment? I don't see how since I was so careful when placing the top back on.
Old 08-08-08, 01:53 PM
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I flipped it upside down and the levels looked good, so I played with it a little bit as suggested and put it all back together again. It started up and ran for about 20 seconds until at least one bowl overflowed. So I've gone from not enough fuel to too much! Now I've got pools of gas sitting on top of my primary plates and a very flooded engine. I'm gonna let everything air out for a bit.
Old 08-08-08, 01:55 PM
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Sounds like the needles are binding in their bores somehow.
Old 08-08-08, 02:08 PM
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Interesting... It did seem like the tab on the problematic one was bent to one side a little. But it went up and down in the bore smoothly.
Old 08-08-08, 02:49 PM
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You are having problems with your needle valves and/or floats. You shouldn't EVER have to adjust the float levels, even though the stupid carb manual tells you to. Sounds to me like your floats are sticking, and keeping the bowls from filling. Here are a couple of things to try.

1) Burnish the edges of the needle valve housings (the square brass pieces). Take the back edge of a butter knife, or spoon or something and rub all four corners of each one. This will help to polish the corners up to a very smooth finish. You should see them get shinier when you rub them. This may stop them from sticking.

2) If that doesn't work then get some floats out of a used carburetor and CAREFULLY swap them into your carb. It is VERY difficult to get your floats bent back correctly if you've messed with them. They should NEVER need adjusting, EVEN if the manual tells you they do. Also grab the needle valve springs and swap those into your new needle housings. Sometimes the springs that come in the rebuild kits are funky and the floats either sit too low or too high. I had this problem once and switching to used floats and needle springs fixed it right up.

Good luck. I'm 95% sure this is your problem.
Jamie
Old 08-08-08, 03:42 PM
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You have to be very careful when putting it all back together. Unless the floats are positioned just right, those tabs and **** will get hung up and keep the float from moving (either up or down). All I can say is take a really good look at them and see how it all works, then maybe you'll identify the cause of the issue. Best of luck to you...
Old 08-08-08, 07:46 PM
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I might try going back to the old needles tomorrow. I had the car running for a couple minutes today, and the bowls finally filled to the correct level. But after a couple minutes, the level got low again and the engine slowly died. Now I'm back to the same situation I had yesterday, where it will start up for a few seconds and die.
Old 08-11-08, 08:32 AM
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Check the connections on the trailing ignitor. If that is not working, or only working part time, then the fuel pump will not run...
Old 08-11-08, 09:26 AM
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The fuel pump is definitely running and putting out pressure. The tach bounces as well so I don't think I'm having a spark issue. I haven't had time to mess with this thing in the past couple days since the clutch slave blew out in my TII. So now I have 2/2 sevens down! Figures, eh?

I think the floats might be the problem... they didn't quite match up, and at least one looked a little bent. I'm guessing I wasn't gentle enough the first time I pulled off the top. I'm picking up a spare carb today and I'm going to pull the floats out of it and try those. After I'm done fixing the second gen, of course. I hope two drivable RX-7's in one day isn't too much to ask!
Old 08-14-08, 01:25 PM
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An update for posterity.... it RUNS! A friend gave me a spare carb, so I swapped the floats out of it and that seems to have solved the problem. A note for those rebuilding for the first time: be careful when removing the top end of the carb! Pull it straight up nice and easy to avoid bending up your floats on the side of the bowls. Now here's the funny thing... when I reinstalled the bowls the last time, I switched them out left for right and didn't really think about the situation logically. They're symmetrical! So that really screwed things up worse than before. That's what happens when you work on your car in pure "**** it, I'm tired" mode.

After all that, it still stumbles when I blip the throttle under 2k. The accelerator pump gasket was replaced, so the only thing I can think of doing is maybe increasing the volume with extra gasket paper via Sterling's AP mod. The rebuild did help quite a bit though - my warm idle is right were it should be and it no longer hesitates if I just barely give it gas, so drivability has improved. I hope this thread helps someone else get their car running down the road.

Thanks everyone for your advice and input!
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