23 replies to this topic

[JCmini]

Hi all. 

I have a 1991 998 Automatic. 

I had a leak under my float chamber so I took the carb out hs4. It turned out the o ring was perished. 

I put it all back together with new ring and fired  it up. All good no leak and idles fine. 

 

I went for a drive and as soon as i put the throttle down the car completely bogged down and spluttered. It felt like the car was runnning really lean or really rich.  I refilled the dash pot as some leaked while taking the carb out. I rechecked the mixture with colortune thinking might be mixture but thats all fine now. I've opened up the float lid and plenty of fuel in there. Choke cable and throttle cable are tight. I ended up driving back on the choke cable as the throttle would just bog the engine down.  Stationary in P. When I rev the engine it goes up then splutters straight away like its dying. 

 

any ideas? 

[Maccmike8]

Id make sure the choke isnt stuck such us pushing the waxstat up with your hand.

Could the o ring be not fitted correct and therefore impeding flow?

[JCmini]

Choke is fine. It moves up and down freely. O ring seems to be fine cant really tell unless I take out the carb again and re fit. 

 

Just weird. Starts fine idles fine. As soon as I go to pull away it bogs down. Then I have to use the choke cable to drive it back home. 

 

Just annoying. It was running perfectly apart from the fuel leak issue. 

Edited by JCmini, 09 December 2020 - 05:38 PM.

[Quinlan minor]

I know it's a long shot but, for my peace of mind, try running it with the air filter off?

[MiniMadRacer]

Can you lift the dashpot piston up with your finger and does it drop down correctly, there should be noticeable pressure on your finger lifting it up, as its full of oil...silly, but did you put the spring back in ?

[JCmini]

So I can lift the piston up and there is resistance. Then when I let go it plops back down. I had to use some 5w40 oil as that was the only oil I had lying around. Do you think that would make a big difference? 

 

And I've been driving it with the air filter out just for test drives so thats not the problem

[MiniMadRacer]

Is the oil syntetic 5w40.. if so it may be way to thin .. but others may have a different opinion...

[Maccmike8]

Engine oil is perfect for it. Mini oil that is. Maybe thats the problem.

[cal844]

Use 20/50 engine oil but as your car is an auto try some of the oil you last serviced it with in the dashpot, to the correct level

[JCmini]

Yeah its semi synthetic for my audi. 

The only other oik have have is 10w40 MA2. Or some gearbox oil. 

 

I might just pick up some Sub carb oil tomorrow to eliminate that problem. 

[JCmini]

Duplicate

Edited by JCmini, 09 December 2020 - 07:34 PM.

[JCmini]

duplicate 

Edited by JCmini, 09 December 2020 - 07:34 PM.

[AndrewT]

How long does the piston take to drop back down? If it's less than about a second then it's moving too fast. This would cause the symptons you are describing on throttle.

[cal844]

Yeah its semi synthetic for my audi.
The only other oik have have is 10w40 MA2. Or some gearbox oil.

I might just pick up some Sub carb oil tomorrow to eliminate that problem.

Try the 10/40 oil, but you may well need 20/50

[JCmini]

I think it does drop back down quite fast. 

I think you guys might be onto something with the dashpot oil. 

Well I went to test drive it but then the throttle cable decided to be sticky. So that's messed up my plans. Have to wait now for new cable. 

 

Might try some 3 in1 oil. Seems to be recommended a lot and much cheaper than su carb oil. Unfortunately I dont have 20/50 any more as my mini is automatic so no need for the classic stuff.