1500 SP runs rough when warmed up

Our Semi auto bettle with a 1500 SP has started to run rough when it has warmed up. It misses quite badly on idle and take off but as the revs get to about 2000 rpm it starts to run perfectly again. It runs beautifully when it's cold.

I think I may have a blockage in the idle jet in the carb (a PICT 30) and maybe when the revs come up the main jet comes in and it starts to run smoothly. Does this sound right? I 'm just after some info before I go and pull it apart..........thanks.

Sounds like what my Auto Beetle was doing, and it was the points.

Check this thread out too, it may help you: http://forums.aussieveedubbers.com/viewtopic.php?tid=46217

🙂

Thanks, that has given me a few things to look at.

sounds more choke / air leak problem


When it is cold the leak is closed. As the motor warms up the leak opens

At idle there is less air required. The amount of air coming in is a higher % and stuffs things up.
At higher revs you are sucking a lot and it doesnt matter as much.

A blocked idle jet would affect the idling hot or cold.

A leak is dangerous to you motor as it is leaning things out and cause you motor to run hot


That is my theory anyway :jesus

does your choke butterfly sit open (vertical) when the engine is warmed?

[ Edited on 5-12-2005 by Anthiron ]

Bizarre wrote:sounds more choke / air leak problem


When it is cold the leak is closed. As the motor warms up the leak opens

At idle there is less air required. The amount of air coming in is a higher % and stuffs things up.
At higher revs you are sucking a lot and it doesnt matter as much.

A blocked idle jet would affect the idling hot or cold.

A leak is dangerous to you motor as it is leaning things out and cause you motor to run hot


That is my theory anyway :jesus

A leak where? In the intake manifold or carby?

Anthiron wrote:does your choke butterfly sit open (vertical) when the engine is warmed?

[ Edited on 5-12-2005 by Anthiron ]

I'll check this out when my wife brings the car home from work tonight.....

64vwmark wrote:[A leak where? In the intake manifold or carby?

Somewhere.............

Crack in manifold

around where it joins on of the heads

where carb joins manifold

A bugger to find.....you can spray WD 40 on these places and see if the idle changes when the fluid momentary blocks the hole/leak

I'll give that a try before I take anything off it.

has this only just happened??

Always happened??

Any reason a leak "could have" developed??

I was out of town when my wife rang up and told me the car has just started to run rough all of a sudden. So it really started a couple of weeks ago. When first looked at it the air cleaner (oil bath) was loose so I tightened that also the vacuum hose that goes to the solenoid for the clutch had come off so I put that back on. We haven't had the car for long (a couple of months) but it was ok for the first few weeks. The previous owners said that it had been sitting in their shed for the last 12 months, so now i'm thinking I may have a gasket that has dried up and cracked.

64vwmark wrote:...........also the vacuum hose that goes to the solenoid for the clutch had come off so I put that back on. ................

hmmmm....vacuum..............

I will bet a beer this has something to do with it

Check that hose for cracks

Yes you could have a point there. If it is just that it will be easy to fix.

Well the first thing I noticed was the coil was only being held in by one bolt instead of two, so I bolted this on correctly. Next I checked the vacuum hoses for the clutch solenoid and the distributor, both in good condition, however the vacuum pipe for the dizzy is a metal tube with rubber hose on each end. On one end it wasn't quite on properly (but looked like it did), so I put this back on properly. Also the wire from the dizzy to the coil has had the insulation partially dissolved by oil so I re-insulated the wire and put it back on.

I took it for a test drive and now it runs like a dream. I think the vacuum hose for the dizzy is the most likely culprit.

Thanks for everyone's help.

Mark

Glad you found what it was. Happy Beetling! :P Autos are the best. 😀

:beer

Pretty_Blue_Bug wrote:Glad you found what it was. Happy Beetling! :P Autos are the best. 😀

Autos are great, so cruisy to drive

Yes bizarre you were right, so one beer for you :beer