4 replies to this topic

[RowlsMini]

The car was running fine until the other day when I tried to start it up.  It was hard to start and once it did start it wanted to idle at 2,000 rpm (instead of the usual 1000) and this with the choke off and no pressure on the gas pedal.  If I touched the throttle softly or gave it a blip it would go up to 3,000 and stay there.  I adjusted the Idle Speed Screw to 1/2 turn in and the Mixture Screws to 1 turn out and started the warm engine.  The revs went to 3,500 before I shut it off.  This with the choke off and the throttle plates closed.  Suggestions? Thanks (a 1989 JDM 998 mini with supercharger)

[NZMini1275]

Firstly check that the return spring is actually pulling the throttle plates fully closed
Any wear in the spindle or bearings can cause the plates to bind slightly
Also check for air leaks where the Weber joins the supercharger

[Earwax]

Check cable is not kinked or getting hung up (not returning fully) where sheath ends and cable continues.

 

As suggested above check the throttle plates are returning to fully closed..... NZ mini may have also given this suggestion ...... (just making sure of the hidden spring)  check under the choke blanking plate ( between the two chambers,, will have to unscrew).. a small spring to assist return to closed ,  it can break and jam open

[nicklouse]

If you have not changed anything look to air leaks. Particularly on the mounting system.

[RowlsMini]

Thanks for the responses.  The throttle plates were definitely closed.  I took the carburetor off the supercharger and removed 

• carburetor cover
• float needle valve
• main, idle, pump and starter jets
• starter valves
• bottom well cover

I found rust deposits and the side of one of the starter valves was scratched and had deposits (not rust) on it.

I cleaned everything and replaced the starter valves with new ones.  Put it back together and so far it's running fine.  It appears it may have been a sticking starter valve but it's a mechanical link to the external control lever and the lever was in the closed position.

May have been several things.