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Possible fueilng problem?


TGJR

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My Carrera 3.0 with K Jetronic has an issue which is getting worse. I was wondering if anyone on here has had/heard of the same symptoms as I suspect it is an issue in the fuel injection system.

The problem is most apparent if you drive on light throttle, eg. 30mph in 4th gear the engine becomes very jerky. It used to be more of an issue when cold but seems to do it when warmed up as well now. Under full load such as hard acceleration it is fine and there is no noticeable misfire. I have not noticed a drop in performance.

Just yesterday I started it up, backed it out of the garage and left in running whilst locking up. The engine idle started dipping, picking up, dipping and then stalled. This has never happened before in my 10 year ownership so could be significant to the problem I have.

Thomas

 

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This is a very common issue and many people just live with it. While idling it is called "hunting" and can be several things. Many will say check your vacuum lines. IMHO it is the result of a combination of things, vacuum, decel valve, WUR etc and you may never get to the bottom of it. Don't forget you are dealing with a 40 plus year old system. Many other opinions will now follow........

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Hi Thomas

I do have similar issues with my 1976 C3, although it is not used as much as yours! I would check that the warm up regulator (WUR) is working properly, I did have a WUR refurbished on another engine and it cured a poor running problem. Have you had the fuel injectors cleaned or replaced during your ownership?

It is a case of trial and error to find the cause. If you really get stuck then I have CIS guages, WUR regulator and even a complete CIS system to try if you fancy a long drive down to Lincolnshire!

Regards

Ian

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7 hours ago, waddy said:

Hi Thomas

I do have similar issues with my 1976 C3, although it is not used as much as yours! I would check that the warm up regulator (WUR) is working properly, I did have a WUR refurbished on another engine and it cured a poor running problem. Have you had the fuel injectors cleaned or replaced during your ownership?

It is a case of trial and error to find the cause. If you really get stuck then I have CIS guages, WUR regulator and even a complete CIS system to try if you fancy a long drive down to Lincolnshire!

Regards

Ian

Hi Ian,

I have not had anything done to the fuel injection system in the 10 years and around 30k miles of ownership - I’ve been lucky!

Cleaning the injectors is an idea as a simple start and the car is due to go to MB when he has space but thought I’d try and get a head start on sorting this. I have been for a drive today and it is by no means terrible but at the same time it is lumpier at lower revs/speeds than it used to be.

Thanks for the offer to try out replacing the parts mentioned. If all else fails......

regards,

Thomas 

On 9/28/2018 at 8:22 AM, Jonny Hart said:

Take the air filter off and check the screws inside the air box to the right of the plastic ribs.   Are they tight?

Thanks, I will have a look at this too.

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  • 6 months later...
On 9/29/2018 at 6:53 PM, TGJR said:

Hi Ian,

I have not had anything done to the fuel injection system in the 10 years and around 30k miles of ownership - I’ve been lucky!

Cleaning the injectors is an idea as a simple start and the car is due to go to MB when he has space but thought I’d try and get a head start on sorting this. I have been for a drive today and it is by no means terrible but at the same time it is lumpier at lower revs/speeds than it used to be.

Thanks for the offer to try out replacing the parts mentioned. If all else fails......

regards,

Thomas 

Thanks, I will have a look at this too.

Hi Thomas - did you ever resolve this issue? If so, what was it? Thanks, Marcus

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