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Engine not idling

vpogv

Member
I'm looking for any input from those a bit smarter than me as to what else could be causing an engine to run and rev great but refuse to idle. What I have:
1600cc engine​
Solex PICT 31 carb that I just tore apart, cleaned and did a basic rebuild​
New plugs and wires​
All vacuum ports plugged​
Distributor timing set and verified plug wires are correct​
I have relentlessly adjusted and reset the idle speed and mixture screws with 0 affect.​

My next steps are to verify spark on each cylinder and then to double check that the jets some how didn't get mixed up before I received the engine. Other than that I have no idea what else to try.

Thoughts?
 

vpogv

Member
An update: Yesterday I was out fumbling with the idle and decided to check the float bowl again after it ran. Thing was empty! Thought perhaps vapor lock caused by the fuel pump flange pinching the rod when it heated up. Made sense to me!

Pulled the fuel pump flange and lightly sanded down the outside of it (like this). While the carb was back off anyway I yanked the jets back out and blasted them with carb cleaner and followed up with compressed air this time. Reassembled everything and it refused to start... yup, out of gas. 🤦‍♂️Oh well!

I am not sure if it was vapor lock or I did a terrible job cleaning the carb but after I added gas, slightly played with timing and adjusted the bypass screw out I have idle! A little high, maybe rough but it's step. Going to yank the carb pack off soon and do a better cleaning job then go from there.

LINK
 

dschwesinger

New member
An update: Yesterday I was out fumbling with the idle and decided to check the float bowl again after it ran. Thing was empty! Thought perhaps vapor lock caused by the fuel pump flange pinching the rod when it heated up. Made sense to me!

Pulled the fuel pump flange and lightly sanded down the outside of it (like this). While the carb was back off anyway I yanked the jets back out and blasted them with carb cleaner and followed up with compressed air this time. Reassembled everything and it refused to start... yup, out of gas. 🤦‍♂️Oh well!

I am not sure if it was vapor lock or I did a terrible job cleaning the carb but after I added gas, slightly played with timing and adjusted the bypass screw out I have idle! A little high, maybe rough but it's step. Going to yank the carb pack off soon and do a better cleaning job then go from there.

LINK
is your float level in the bowl adjusted to the right level sometimes it can change just by moving it around causing it to shut off the gas. Sounds like the float are stopping it from filling up
the bowl hence forth no gas to run the car
 

vpogv

Member
is your float level in the bowl adjusted to the right level sometimes it can change just by moving it around causing it to shut off the gas. Sounds like the float are stopping it from filling up
the bowl hence forth no gas to run the car
I am not away of a way to adjust the float level. The fuel was definitely way below the float anyway so simply wasn't getting there. I'm going with out of gas.
 

dschwesinger

New member
I am not away of a way to adjust the float level. The fuel was definitely way below the float anyway so simply wasn't getting there. I'm going with out of gas.
there is a tab that rests on the needle valve you bend it up or down depending on the height of the float when its just barely resting on the needle value.
there are videos on YouTube for just about everything I'm sure they have one for your carb.
 

vpogv

Member
Just to update where things are - the car starts and runs but dies about halfway through the warm up. The car is flooding itself and I am at a loss as to why.

  1. Adjusted all the valves to within spec. Only 1 was a bit loose which I tightened up the gap.
  2. Verified TDC and set timing to 10* BTDC.
  3. Replaced all plugs and wires.
  4. Tried 2 different distributors and caps - spark looks good and blue.
  5. Tried two different carbs (both were cleaned and rebuilt)
  6. Replaced the intake with one with heat risers to reduce the chance of freezing.
  7. Checked Fuel pressure which was just a bit above 4 PSI. Got it down to 2.9PSI at idle.

After all of this after starting the car and letting it idle for a minute or two it just dies. Pulling the carb shows fuel sitting in the intake tube. This screams carb issue but the same things happens with 2 different carburetors. Am I really that unlucky?

Tomorrow I am going to change the oil to get any gas out of there but beyond that I am so lost.
 

letterman7

Honorary Admin
Step up the idle not with the mixture screws but by the actual stop on the throttle arm. This contradicts what the step by step says, but you have to get it idling at some point. The fine tune adjustments can come later. I'm not sure that I've ever encountered a VW that didn't run a little rich, even with Webers installed. Over rich will water your eyes. A little rich you can just smell it...
 
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