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Carlos_1300L
Samba Member
Joined: February 01, 2023
Posts: 59
Location: Portugal
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 Posted: Sat Jun 28, 2025 7:42 am Post subject: High rev to idle too slowly |
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Hey everyone,
I have a problem on my 1970 1300 VW.
When i’am on relatively steep descents, the engine stops.
I tested to tune the carb (just one carb) and I noticed that when I rev the engine, it drops back to idle slowly.
Can someone help-me solve de problem?
Thanks |
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4210
Location: WA
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| Posted: Sat Jun 28, 2025 12:59 pm Post subject: Re: High rev to idle too slowly |
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| Sounds like the float lever is too high. Start the motor and let it run for 1 minute and shut it off and remove the top of the carb. and see where the fuel level is. |
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Carlos_1300L
Samba Member
Joined: February 01, 2023
Posts: 59
Location: Portugal
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| Posted: Mon Jun 30, 2025 9:22 am Post subject: Re: High rev to idle too slowly |
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| Starbucket wrote: |
| Sounds like the float lever is too high. Start the motor and let it run for 1 minute and shut it off and remove the top of the carb. and see where the fuel level is. |
The carb is a Solex 30 PICT-2.
The float is only adjustable by washers.
I measured the distance and the fuel was about 19,5 mm from the top of the carb.
Is that ok or I need one more washer?
Thank you |
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Chinaclipper
Samba Member
Joined: October 03, 2019
Posts: 807
Location: Somewhere in the great Midwest
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| Posted: Mon Jun 30, 2025 9:37 am Post subject: Re: High rev to idle too slowly |
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| Carlos_1300L wrote: |
Hey everyone,
I have a problem on my 1970 1300 VW.
When i’am on relatively steep descents, the engine stops.
I tested to tune the carb (just one carb) and I noticed that when I rev the engine, it drops back to idle slowly.
Can someone help-me solve de problem?
Thanks |
I guess I'll ask first: 1) Where are you with idle speed now? Should be around 850 rpm-900 RPM when the engine is warmed up, IIRC. 2) Is your choke wire connected? Is the choke properly adjusted? 3) Have you checked points and ignition timing?
Good luck!
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https://www.thesamba.com/vw/forum/viewtopic.php?t=728089&highlight= |
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Carlos_1300L
Samba Member
Joined: February 01, 2023
Posts: 59
Location: Portugal
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| Posted: Mon Jun 30, 2025 9:43 am Post subject: Re: High rev to idle too slowly |
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| Chinaclipper wrote: |
| Carlos_1300L wrote: |
Hey everyone,
I have a problem on my 1970 1300 VW.
When i’am on relatively steep descents, the engine stops.
I tested to tune the carb (just one carb) and I noticed that when I rev the engine, it drops back to idle slowly.
Can someone help-me solve de problem?
Thanks |
I guess I'll ask first: 1) Where are you with idle speed now? Should be around 850 rpm-900 RPM when the engine is warmed up, IIRC. 2) Is your choke wire connected? Is the choke properly adjusted? 3) Have you checked points and ignition timing?
Good luck! |
Thanks for the answer:
1- yes, about 870rpm;
2- the choke is working fine;
3- yes, when the problem comes, the first thing I did was adjust points (Dwell angle check too), and timing.
Need to say the car was running very well and suddenly the problem appears. |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 16559
Location: North Florida, USA
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| Posted: Mon Jun 30, 2025 12:30 pm Post subject: Re: High rev to idle too slowly |
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19mm = 3/4in which is correct fuel level for a Solex Pict carb.
Make sure the U-shaped clip that holds the float pin down (top of pic below) is oriented correctly as shown below:
Check if your intake is firmly mounted. Grab the carb and push-pull to see if the intake can rotate around the lower tube running between the end castings. There should be a bracket from one of the carb mounting bolts to the top of the case to prevent the intake from moving at all. Without this the intake could tilt the carb when you are pointed downhill causing fuel to overflow down the intake.
One more thing to check... fuel pressure. You ideally want something in the 2~3psi range. Much more than this and you can overwhelm the float.
Lastly check for any loose wires. If something were to short the ignition coil #1 (-) terminal it would prevent the coil from generating a spark.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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Carlos_1300L
Samba Member
Joined: February 01, 2023
Posts: 59
Location: Portugal
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| Posted: Mon Jun 30, 2025 1:18 pm Post subject: Re: High rev to idle too slowly |
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| ashman40 wrote: |
19mm = 3/4in which is correct fuel level for a Solex Pict carb.
Make sure the U-shaped clip that holds the float pin down (top of pic below) is oriented correctly as shown below:
Check if your intake is firmly mounted. Grab the carb and push-pull to see if the intake can rotate around the lower tube running between the end castings. There should be a bracket from one of the carb mounting bolts to the top of the case to prevent the intake from moving at all. Without this the intake could tilt the carb when you are pointed downhill causing fuel to overflow down the intake.
One more thing to check... fuel pressure. You ideally want something in the 2~3psi range. Much more than this and you can overwhelm the float.
Lastly check for any loose wires. If something were to short the ignition coil #1 (-) terminal it would prevent the coil from generating a spark. |
I noticed that throttle linkage was making some noise when the lever goes down. Possibly because the retaining rings on the pump arm were not totally in place.
It could possibly not allow the throttle plate to close totally the Venturi.
I put it in place and tomorrow I will test.
Thanks |
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Carlos_1300L
Samba Member
Joined: February 01, 2023
Posts: 59
Location: Portugal
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| Posted: Fri Jul 04, 2025 3:34 pm Post subject: Re: High rev to idle too slowly |
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Problem solved!
It was the pump arm that is attached to the throttle shaft. It wasn’t allowing the throttle lever to return completely.
Thanks everyone! |
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