Datsun pickup Posted January 12, 2023 Author Report Share Posted January 12, 2023 Would the throttle cable have anything to do with it? Quote Link to comment
datzenmike Posted January 12, 2023 Report Share Posted January 12, 2023 Yes if it's been off and then put back on incorrectly. Quote Link to comment
Datsun pickup Posted January 19, 2023 Author Report Share Posted January 19, 2023 (edited) Where is the idle adjustment screw? My choke plate doesn’t move at all, it is slightly open. How would you fix that? Edited January 19, 2023 by Datsun pickup Quote Link to comment
datzenmike Posted January 19, 2023 Report Share Posted January 19, 2023 Hold the choke plate open and then open and close the throttle. Did it close that time? Quote Link to comment
datzenmike Posted January 19, 2023 Report Share Posted January 19, 2023 Stuck? Try hosing down the external linkages with WD 40 and wiggle everything to loosen. If the choke is on so is the fast idle and if that's the case there is no sense messing with the idle speed screw till fixed Quote Link to comment
Datsun pickup Posted January 22, 2023 Author Report Share Posted January 22, 2023 What is the best way to setup a manual choke on the stock carburetor. Quote Link to comment
datzenmike Posted January 22, 2023 Report Share Posted January 22, 2023 Your '85 is set at the factory and is not adjustable. Early choke were not like this. All you can do is go out in the morning when cold and take the top off the air filter. Have someone step on the gas and it should snap closed. If it does, it's working. On the one I had the choke was riveted on. I drilled them out and put in 3 screws... There was also a tab that prevented the black housing from turning. So I ground it off. Now its free to adjust. I left it snug but you could twist it by hand. On really cold mornings it didn't stay on long enough so I just reach in and turn it towards richer. In the summer the fast idle is on too long so I turn it leaner. Quote Link to comment
Datsun pickup Posted January 23, 2023 Author Report Share Posted January 23, 2023 (edited) The fuel pump runs but no fuel gets to the carburetor. What is wrong? How do the choke and throttle work together? Edited January 23, 2023 by Datsun pickup Quote Link to comment
datzenmike Posted January 23, 2023 Report Share Posted January 23, 2023 But you said... On 5/7/2022 at 7:19 AM, Datsun pickup said: The float chamber is filling up with gas. The needle works just fine. Is there a tool to adjust the float? I tried adjusting it, but nothing has worked. On 6/30/2022 at 1:04 PM, Datsun pickup said: I have my float adjusted properly, but the fuel pump does not stop, so the bowl fills up with fuel. Would the fuel pump have anything to do with my problem? On 1/11/2023 at 2:06 PM, Datsun pickup said: How do you adjust the idle? It is currently idling at about 2,250 rpm. Is that normal? Dirty plugged fuel filter? There should be one between tank and pump. The bottom of the pump twists off and there is a filter there also. Fuel line from pump is clogged. Quote Link to comment
Datsun pickup Posted January 24, 2023 Author Report Share Posted January 24, 2023 How does the throttle work with the choke? Quote Link to comment
datzenmike Posted January 24, 2023 Report Share Posted January 24, 2023 I would say the choke works with the throttle. Engines require that the fuel droplets mixed with air by the carburetor have to vaporize in order to burn. Much of it is vaporized by warm/hot engine parts on the way to the combustion chamber but when the air and engine are cold this is much reduced and the engine runs poorly or not at all. A choke forces a much richer fuel mixture of which more fuel evaporates. The choke has a coil made of two different metals that expand at different rates when warmed. When warmed the coil unwinds slightly and when it cools it coils up tighter. There is also an electrical heater that provides warmth at a set rate so the choke coil open fully in 8-12 minutes depending on how cold it is. On cold startup the choke that was previously unwound has cooled and contracted trying to close the choke flap but the throttle is in the way. The driver steps on the gas pedal and the choke, now released, snaps closed. The engine is started and the electric heater begins to warm the coil. During engine warm up the coil slowly unwinds and opens the choke flap and by the time it's fully open the engine is warm and does not need the choke on. At the same time, there is a fast idle cam connected by a linkage to the choke that drops down and blocks the throttle from fully closing and this extra air and the rich mixture from the choke being closed revs the engine speeding the warm up. As the choke coil unwinds the fast idle is slowly reduced till normal idle speed is achieved. Quote Link to comment
Datsun pickup Posted January 24, 2023 Author Report Share Posted January 24, 2023 My choke does not snap closed when the throttle is pressed. Fuel is getting to the carburetor, but not pass the accelerator pump into the intake. Quote Link to comment
datzenmike Posted January 25, 2023 Report Share Posted January 25, 2023 If you hold the throttle slightly open can you close the choke flap by hand??? Quote Link to comment
Datsun pickup Posted January 25, 2023 Author Report Share Posted January 25, 2023 Yes. Quote Link to comment
datzenmike Posted January 25, 2023 Report Share Posted January 25, 2023 Does you choke have three screws that can be removed? The underside has the coil and it has a J shaped end... The choke flap has a tang sticking out that is caught in the end of the J or should be Quote Link to comment
Datsun pickup Posted January 25, 2023 Author Report Share Posted January 25, 2023 Yes, mine has all of that. Quote Link to comment
datzenmike Posted January 25, 2023 Report Share Posted January 25, 2023 The one pictured is adjustable by loosening and turning the black plastic part to wind against the coiled spring inside. Richer is tighter. I think yours being an '85 is not adjustable and is set at the factory. Well make sure the choke flap is hooked around that J shape on the end of the coil. Perhaps the coil is broken? Quote Link to comment
Datsun pickup Posted January 25, 2023 Author Report Share Posted January 25, 2023 I made sure that the J was hooked around the choke flap and I think it works now. As the fuel pump runs the fuel pours into the intake and it wants to run away. What would cause all the fuel to pour into the intake? Quote Link to comment
Crashtd420 Posted January 25, 2023 Report Share Posted January 25, 2023 (edited) 11 minutes ago, Datsun pickup said: I made sure that the J was hooked around the choke flap and I think it works now. As the fuel pump runs the fuel pours into the intake and it wants to run away. What would cause all the fuel to pour into the intake? Sounds like a stuck float.... or sunk... What should happen is when the gas fills the carburetor the floats rises closes the needle and seat on the inlet to stop gas from flowing in once full... Edited January 25, 2023 by Crashtd420 Quote Link to comment
Datsun pickup Posted January 25, 2023 Author Report Share Posted January 25, 2023 The float rises and everything is adjusted how it should be. Quote Link to comment
datzenmike Posted January 25, 2023 Report Share Posted January 25, 2023 The stock Hitachi has a small round glass in the front with a white dot in the center. This displays the proper fuel level. The front is also held on with 3 screws so you can access the float to adjust it. Have a cloth under the front to catch the fuel and there is a small brass part on the hinge bur against the front cover. It almost always falls out. 1/ float may rise but not be adjusted properly to shut off fuel through the needle valve. 2/ needle valve on end of float may have dirt or something blocking it from fully closing and it will over fill and drain into the intake. The needle valve is below the banjo fitting on the inlet. Quote Link to comment
Datsun pickup Posted January 25, 2023 Author Report Share Posted January 25, 2023 The fuel is going everywhere, it overflows the entire carburetor, enters the vacuum system, and floods basically everything. Quote Link to comment
datzenmike Posted January 25, 2023 Report Share Posted January 25, 2023 I know. This is what happens if float is set wrong or needle valve is blocked from closing. Quote Link to comment
Datsun pickup Posted February 21, 2023 Author Report Share Posted February 21, 2023 Does the nissan 720 have a governor? My truck won’t start because it seems like it doesn’t get fuel, but when it does it starts right up but gets too much fuel. Is this problem related to the choke? Quote Link to comment
datzenmike Posted February 21, 2023 Report Share Posted February 21, 2023 No governor. Next time the engine is cold go out and take the top of the air filter and look. Choke plate, or flap, should be part open. Have someone step on the gas. Choke plate should snap closed. This is normal. If weather is cold when starting a cold engine, pump the gas two or three times first then start and see if the starting is improved. Quote Link to comment
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