Surging Idle

[Guest Bobbers]

I was out for a run in my s7 2.1 pinto with 38 dgas Webber when I noticed it was a bit rough at low throttle openings ,at the traffic lights it was surging badly and trying to stall . It still revs and pulls fine so it's only a slow running fault . I know squat about carbs so any suggestions would be great .

[Guest 2b cruising]

Rich mixture.

Air leak inlet side between carb and engine including ancillaries. Servo. Dissy vacuum etc.

Idle speed itself set to low.

These are common faults.

Check these first and come back if not found.

No need to go technical yet.

Use an oil can on gasket joints etc and see if it momentarily sorts itself.

[Guest Bobbers]

I'll check them , it's something that failed not adjustment as it was idling fine one minute then next set of lights all surging

[Guest Bobbers]

I wonder if a diaphragm has split ?

[tractor]

thats webbers for you good one minute bad the next

[Guest Bobbers]

Fixed it , looked like remains of insects in float bowl and something that resembled snot

[Guest Ian & Carole]

That could be the remains of some silicone sealant. If someone has used that to seal parts of the fuel system it could be clogging your petrol filter too, might be worth a replacement there too

I find it hard to believe that Mick Ebbs (mowerman) would use silicon on his car, he is far to careful and experienced for that.

 

I would change the filters and run a fresh tank of fuel through it.

[Guest 2b cruising]

If Mick bought it road ready and has had no call to do any maintenance pipe wise or sender, it could still be something like that.

Old fuel can also jellify, if that's a word. Especially lead free.

No need of blame as you know how good Mick is.

I've not met him in the flesh yet, but I trust his word on here on any car subject.

Bobbers, well done, lots of people would have given in by now.

Get out and enjoy.

[Guest mower man]

Hi its mick , dont know where the creepy crawlies are from but I did use silicon when modifying the tank sender and imeadiatly had trouble cleaned the system out ,blown both ways new in line filter etc ran ok for a few months before bobbers bought it including a spirited drive to deliver it and it is awhile ago any thing is possible ,the idle circuit is fiddly on that carb and caused me some hair pulling and bad language periods get in touch if its still being awkward keep well and give it a thrashing now and then it loves it.

Thanks for the votes of confidence people ! am still playing with the MX5 and loving it mick ps I am not perfect but try to be ,last thought clean the idle jets out and blow though the carb [ air llne not lips]

Edited May 14, 2016 by mower man

[Guest Bobbers]

It's running great again now mick , probably gunked up thru just being left all winter . I fixed the just off idle flat stop by fitting a fuel pressure regulator it made a big difference I'm looking forward to some good runs out this summer