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Stalling- running issues


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So I've been having issues with my truck stalling constantly. I tried adjusting the idle mixture as well as idle speed it helped for about a day. It bogs down and shudders when I'm driving, or slowing down to a stop. I'm thinking of rebuilding the carb. Is there a certain kit I should get? Also any good links for cleaning the gas tank? 

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For a good idle you need a good strong intake vacuum. Bad timing and over tight valve lash will destroy any idle. So check those first or second. Make sure timing and valve lash are good and move on.



Remove the idle mix screw (count the turns so it goes back the same) and take the idle cut solenoid out carefully... it has a spring and loose pieces inside.


Use a can of carb spray with a straw and spray into the idle cut solenoid hole so it flushes out the idle mix screw hole. Now flush in reverse. Put the idle mix screw back in and spray the idle cut solenoid hole again to push any debris back through the carb. Replace the solenoid and check that when the ignition is turned on and off the solenoid makes a clicking sound. If no sound there may be a problem.

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So I removed the idle cut solenoid and idle mixture screw and carb cleaned it. Seems to run way better. Took it for a drive and seems to drive much better. We will see in the morning how it goes. Thanks guys I will update tomorrow.  Also I'd love to put a weber on it but I dont want to spend all that money just yet. 

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So I drove it to work and the issue is still there. I'm going to get the carb rebuilt and clean out the fuel lines and drain the tank to see what that looks like. Any tips on the electric fuel pump? I believe it is the faccet one. Would it be easier to remove the bed to access everything better? I'm just trying to make this thing daily drivable without worrying about it breaking down.  Also will be getting a timing light to see what a going on there. Needless to say I'm pretty frustrated with this thing. 

Edited by Justin620datsun
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You would only have an electric fuel pump if your '79 originally came equipped with an air conditioner, otherwise you have a mechanical pump on the front right (pass side) of the head


The electric fuel pump is located on the outside of the passenger side frame rail just forward of the rear leaf spring mount.


There is (or should be) a plastic fuel filter in line before the electric pump and a twist off bottom on the electric pump with a filter inside and a magnet on the cap. I believe there is an old VW bug filter that will fit it?

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They're cheap and should be changed every 2 years.


Do not bother removing the gas tank. The 620 after '74 has a return line to the tank, so during engine running the gas is slowly but constantly being re circulated and filters out any crap in the tank.

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