carb issues

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johnscf
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Posts: 184
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carb issues

Post by johnscf »

having some problems with my 70 1600. previously had trouble going up steep inclines. Sputtered and almost died. Turned out the pressure regulator/ return valve that sits above the rear carb had no guts inside it and fuel was flowing straight back to the tank and not feeding the back carb when going up a steep enough hill. Replaced the regulator and that fixed the problem. Car ran great for about two weeks (which in my case is about 50 miles, 4 or 5 drives of about 10 miles) Now the car idles fine but sputters and cuts out when trying to accelerate and under load. Tried pushing up the pin on the rear carb and car continued to idle fine, when pushing up the pin on the front carb the car stalls out immediately. I think that isolates the problem to the rear carb. Correct? Also found that the rear carb is leaking out the bottom where the nozzle slides into the sleeve that screws in. I can’t tell whether the leak is coming from the nozzle not fitting correctly in the sleeve that attaches to the carb or whether the leak is coming from the sleeve not tightening on the bottom of the carb. I have found the nozzles for sale but don’t see the sleeves on any of our vendor sites. Could it be as simple as replacing the washer on the sleeve? Any thoughts? Picture of sleeve with washer attached.
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Charlie
68 2000
67.5 1600
70 16000
71 Toyota Celica ST coupe
74 Toyota Celica ST coupe
77 Toyota Celica GT liftback
Habitat.pat
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Location: Central Texas
Model: 1500/1600
Year: Low Windshield-64-67.5

Re: carb issues

Post by Habitat.pat »

If you have fuel leaking from the jet, your fuel level is too high. Compare float levels. The fuel level should be just below the top of the jet when fully choked. Take the domes & suction pistons out so you can see the level.

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Pat
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johnscf
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Re: carb issues

Post by johnscf »

Habitat.pat wrote: Tue Oct 12, 2021 5:27 pm If you have fuel leaking from the jet, your fuel level is too high. Compare float levels. The fuel level should be just below the top of the jet when fully choked. Take the domes & suction pistons out so you can see the level.

Peace,
Pat
I will put everything back together and check the levels. Assuming the level is too high, what could cause that to all of a sudden start to happen and more importantly, what do I do to eliminate the problem?
Charlie
68 2000
67.5 1600
70 16000
71 Toyota Celica ST coupe
74 Toyota Celica ST coupe
77 Toyota Celica GT liftback
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jrusso07
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Location: Penn Yan, NY
Model: 2000
Year: High Windshield-68-70

Re: carb issues

Post by jrusso07 »

A couple of thoughts - if fuel level is too high, then either the float in the fuel bowl is not properly adjusted or the needle valve on that bowl has a piece of junk in it which is not allowing it to close. I would bet on the later to explain the "all of the sudden". After getting the level correct, check the banjo bolt screen filters in the carb fuel feed to see if there is a lot of junk/debris on them. Replace or clean them as necessary.
Joe

1969 SRL311 - Solex
1970 SPL311 - U20 mod
1970 SRL311
johnscf
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Re: carb issues

Post by johnscf »

Before I put everything back together to check the levels, another question. I have the rear carb off, as I mentioned above I think I’ve isolated the problem to it. With the dome off of it when I slide the piston up and let it go the needle slides down into the nozzle until the piston bottoms out. The same thing happens on the front carb which seems to be ok. When I put the dome on and push the piston up and let it go, the needle slides into the nozzle but the piston stops short of bottoming out. It seems like it’s being caught or sticking on the way down. If I move the choke lever and drop the nozzle the piston then drops to the bottom. Weird thing is that it doesn’t hang up if the dome is off so I don’t think the needle or nozzle are misaligned or bent. Thoughts?
Charlie
68 2000
67.5 1600
70 16000
71 Toyota Celica ST coupe
74 Toyota Celica ST coupe
77 Toyota Celica GT liftback
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jrusso07
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Joined: Sat Aug 02, 2008 9:02 am
Location: Penn Yan, NY
Model: 2000
Year: High Windshield-68-70

Re: carb issues

Post by jrusso07 »

The dome sets the relationship of the piston to the jet. When you pull the choke you are lowing the jet nozzle in the sleeve and likely moving the point of interference down enough where the needle doesn't rub. Look at your needle for wear marks (shiny areas on the needle) this will tell you if it was rubbing to cause the initial problem. There is a procedure for centering the jet and/or straightening the needle if needed. I would guess the jet nozzle needs to be aligned to the needle. See Page 60 in the service manual (in Tech wiki) for the procedure although the translation to English is a little weird. It works ok when you have the parts in your hand.
Joe

1969 SRL311 - Solex
1970 SPL311 - U20 mod
1970 SRL311
todd lorber
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Re: carb issues

Post by todd lorber »

Before you realign the jet, loosen the dome slightly and keep jiggling it as you tighten the screws (a little at a time) as you keep lifting and dropping the piston. This may provide the proper dome alignment. If that doesn't work, then the nozzle is too far out of adjustment and, as jruss said, it will need to be recentered.