theNeanderthol

iTrader: (1)

well i put on my rebuilt carb today and ran into some problems. I have to give it a little gas to start it an when it starts it revs up to 2000 rpm and stays there for 5 - 10 secs and then it dies. Anyone know what is going on?

Sterling

Sounds like it could be a combination of two different problems.
Running @ 2K could be because:
-You have a leak,
-the idle is way off, (and your mixture, too)
-the secondaries are not completly closed (linkage slightly hung up)

Peer down into the top, and see if the secondaries are all the way shut. Operate the carb by hand to see that the primaries are working smoothly, and shutting all the way till the shaft arm hits the idle screw.

Actually, I would start with the other problem first...Obviously if it is'nt getting fuel, you can't tune it properly!

Yank the hose, and just check the output into a coffee can when you turn it on. (Just make sure there's fuel coming out...You do have fuel in the tank, right?)

Make sure that the "Float Bowl Solenoid" is plugged in. It's a plug on the drivers side of the carb with a single positive wire hooked to it. If it is'nt plugged in, the carb has no vent.

Check the sight glasses by having someone else start the car. Observe if they go down as the car dies.

Peejays answer to everything is to get the hammer out! So try tapping on the top of the bowls lightly with a plastic screwdriver handle and see if they free up.

If they don't, you will have to yank the top and observe the action of the floats and needles. Held upside down, with the floats pushing the needles closed, there should be 9/16 inch between the top of the float and the gasket paper.
If there is'nt this measurement or close to it, then something is'nt right.

Did you install the tiny springs that go inside the needles?

What problems were you having before you rebuilt it?

jeremy

iTrader: (1)

isn't the choke revving it to 2k? and then it runs out of fuel becuase it eats everything in the bowl.

theNeanderthol

iTrader: (1)

I checked for fuel and it is fine. Youre right about the secondaries though, they arent shutting properly. Im not sure why it is running really rough before it dies though. The motor shakes and the exhaust sounds funny. Almost like only one rotor is getting fuel. The float bowl solenoid was in. I got the carburetor from someone else, so i really dont know anything about how well the carb worked before I rebuilt it.
I took off the choke cable to see is there was a difference, but there wasnt, so i guess it isnt the choke. I put in the springs in the needle and seat assembly, so that isnt it. Tried the hammer, but to no avail. I'll deal with the secondaries closing first, and keep you updated. Thanks for the help. Keep the advice coming.

85RX7GS

iTrader: (1)

Check the fuel pump cut relay and be sure it's getting enough gas.

SilverRocket

That's normal when the secondaries are stuck open a bit. The car will idle high and very rough - it will shake all over the place and run *very* rich. It will be smooth when you close the secondaries. When my secondaries got stuck, all it took was a touch of a finger and some carb cleaner to free them up nice.

Can't really help with the other problem.

Sterling

Lean.


There is a screw on the direct diagonal opposite to where the idle speed screw is, and it does the same thing for the secodary throttle shaft as the idle screw does for the primaries. It's a throttle stop, and it's located underneath the vacuum advance linkage. Basically it is just a simple headless screw with a lock nut on it, and it is tiny. It's purpose is to make sure that when the secondaries are closed, they don't get "too closed", jamming shut. Still, they doo need to be fully closed.
These carbs come with this adjustment already taken care of, the locking nut secured, and as a further precaution against "fucked-withness", they add a dab of epoxy.
Since you don't really know the history of this carb, IF you should find that cleaning up all the linkage and checking for binding does'nt seem to be helping you out, check to see if the screw has been tampered with.

You may need an inspection mirror for this. See if the throttle stop is making contact with the back of the screw. If it is, and the secondaries are not fully closed, then that's your idle problem.

Nobody...I mean NOBODY usually ever has a need to touch that adjustment, just so you know.
I'm looking for longshots here for ya!


And, as I wrote before;
Check the sight glasses by having someone else start the car. Observe if they go down as the car dies.
And;
observe the fuel flow that goes to the carb.
This will tell you for certain if you have a fuel delivery failure.

SilverRocket

Sterling,

So how come when my secondaries stuck open I went through a tank of gas in 150kms? (that was until I figured out what the problem was) And I could see gas smoke coming out the exhaust? Isn't that running rich?

Just trying to understand.

theNeanderthol

iTrader: (1)

Well it isnt a fuel delivery problem. My carter is pumping strong. Well I'm gonna take care of the secondary problem and see if it helps. And I'm gonna check the floats. I set them at 17mm upside down and 51mm right side up. Is that correct? Oh yeah, is there any way to get rid of that shutter valve in the intake manifold? It looks pretty restrictive. Thanks a lot guys.

Sterling

It's alot different story when your just sitting there idling. When you're at speed, the carb is gasping for air...alot of air, and the flow through stuck-open secondaries (even if only stuck a little) is then great enough to suck fuel up through the emulsion tubes and out into the booster venturi.
At idle, you have a set amount of fuel metered into the carb, and you control the air flow with a "idle bleed", or "step air bleed". That controls how much air is allowed to go thru little orifices in the primaries.
Then the fine tuning is done with the mixture screw. This is all at low rpm idle speeds.
You could make your car idle at 4000 RPMs if you want to, but then these idle circuit components will have little or no effect. You would then be using the primary circuit in the carb, utilizing air flow thru the venturis to suck out fuel through the main jets. (Basically like driving with no load.)

I'm really sorry, but us backward-*** Americans are'nt taught well in school about wieghts and measures that THE WHOLE REST OF THE CIVILIZED WORLD USES AS AN ALMOST UNIVERSAL LANGUAGE; So could you please tell me how many miles a tank was lasting you?

SilverRocket

Cool, I understand. Thanks.

I figured you were talking about a difference between running at idle and driving... I guess I can qualify my statement by saying it will run very rich while driving.

When my secondaries stuck open, I went through a tank of gas driving from Waterloo to Aurora, Ontario. This is a 1.5 hour drive, about 150-170 kms or around 100 miles. So yeah, somewhere around 100 miles to a tank. Worst gas mileage I've ever seen, although my Dell is close enough haha.

Sterling

6.25 MPG?!?!
Perhaps if you were cruising at 50 MPH @ 2700 RPM having set the mixture screw to compensate...But still, that's really bad!

SilverRocket

No ****, that's why you don't want to run around with your secondaries stuck open!

It might not have been exactly a full tank, maybe it was closer to 3/4. I can't remember exactly. Either way, it was absolutely appalling in comparison to normal fuel mileage.

79+80_rx-7

oh...um.. so I guess 2 miles per 5 gallons is REALLY bad eh? ...... i guess i need to fix that..... maybe then the car wont run like total CRAP!!


THANX, LATERS....Andrew