Cabrio carb

[dogoncrazy]

Re: Cabrio carb

If acceleration is Ok and its running well at steady throttle I can't see fuel starvation as being the cause of rough idle. It just doesn't add up to me.
Has the car been idle over the winter or in regular use, and has the problem just materialised or got worse over time?

[dogoncrazy]

Re: Cabrio carb

Just read on one of the Ford forums that there is a potential cause of poor idle from a small rubber hose behind the exhaust manifold . Seems they crack over time /heat. Replacements have metal shield to prevent this taking place. Maybe worth checking.

[Mickaleen]

Re: Cabrio carb

Hi,
It doesn't add up to me neither.
There isn't a rubber hose behind the exhaust manifold. Having spoken to Webcon it's their opinion that fuel starvation my be the cause of hunting.
So I bought an after market pump to see or at least eliminate the Ford pump from the equation.

[greyV8pete]

Re: Cabrio carb

Aha! Not familiar with that engine so didn't realise you had an ECU. So does it have an idle control valve? If yes then go straight there. Whip it off and clean it out. The ones fitted to the Sierra injection models were notorious for giving poor and fluctuating idle. My friend who had one kept a spare cleaned one in the boot. Swapped it at the first signs of a problem. Then cleaned the other one and popped it back in the boot! On second thoughts maybe only a full injection set up has one?

Agree with dogoncrazy that low fuel supply is unlikely. Checking that hose he mentions sounds like a good lead. Peter.

[Mickaleen]

Re: Cabrio carb

Hi,
There is no rubber hose.
Until I fit and tryout the after market pump I won't know for sure if it is the Ford pump which maybe at fault. A low fuel supply is a contributory factor to hunting, poor idling Webcon said but we will have to wait and see.

[ggrum]

Re: Cabrio carb

Probably not relevant to the carb version but I had an idling and hunting problem with my DOHC Efi engine and I assumed it was the idle control valve. Took it off and cleaned, no difference. Replaced it with a new one and again no difference. Based on a tip I changed the throttle position sensor and the problem was solved. No idea if the carb on the later engines with an ECU had a similar device.

[dogoncrazy]

Re: Cabrio carb

I'm just repeating what I've read so apologies if info is incorrect. You have the engine , I do not.
Still like to know if car was in regular use or not etc etc

[dogoncrazy]

Re: Cabrio carb

If you play around with the idle speed screw to the extent that the throttle flap is moved beyond the idle circuit [ie uncovering the progression hole] then adjusting the mixture screw will have no effect whatsoever. Throttle flap needs to be shut for mixture to be adjusted then idle speed screw adjusted if necessary.
Sorry if that sounds like I'm trying to teach my Granny to suck eggs!

[Mickaleen]

Re: Cabrio carb

Hi,
No throttle position sensor on the carburetor.
I have tried gravity feeding the carburetor and that hasn't had any effect.

[greyV8pete]

Re: Cabrio carb

I still don't understand, has this hunting / idling always been a problem and just got worse, or has it reared its head suddenly and if so when? Peter.

[dogoncrazy]

Re: Cabrio carb

I've asked the same question Peter, but no answer so far!

[Mickaleen]

Re: Cabrio carb

Hi,
This problem has been with me for the last few months. Gradually getting worse over the period.
I'm as frustrated as yourselves.

[lizbillings]

Re: Cabrio carb

Could the timing be slightly out?

[greyV8pete]

Re: Cabrio carb

Hi,
This problem has been with me for the last few months. Gradually getting worse over the period.
I'm as frustrated as yourselves.

Ah that narrows it down a bit! To me gradually worsens equates to gradually failing or wearing out. So being convinced that it is over fuelling at tickover I would then suspect the following.


Diaphragms - Done
Gaskets leak - Done
Jets esp idle - ???
Worn throttle spindle - ???
Needle valve - ???


If the throttle spindle is badly worn then so much air is going in that the mixture screw cannot compensate. A refurb / replacement is then required.


However if the spindle is ok then I would put my money on the needle valve. Get a replacement viton tipped needle and new jet. Reset the correct fuel level and see what happens.


A final thought is to check that the fuel pump is correct delivery pressure for that carb. I would expect 3-4 psi max to be sufficient for a 2L engine. Peter.

[Mickaleen]

Re: Cabrio carb

Hi Peter,
I am unable to check the delivery pressure so I ordered an after market fuel pump which I should have by Friday or Monday the latest. Webcon also suggested I check the delivery pressure they suggested 2 psi at least.
The pump I have ordered is a universal one off ebay. Will hopefully know if it's successful once set up.
There has to be some wear the carburetor is getting on a bit, 25 year old. ( a bit like myself).