Poor throttle response/coughing when driving

[121]

My 1988 1.3 121 seems to respond very bad to throttle action on higher RPMs. She's coughing like hell when I slip her some gas above 3000. Engine responds great when in neutral, it's when I drive this occurs. She also seems very thirsty, and I can't seem to push her above 60-62 mph (unless downhill) :-) What I have done to try to resolve this so far is:

Replaced spark plugs (old ones looked great though)
Measured resistance in all ignition leads, all good
Made sure automatic choke open/close properly, and it does
Checked ignition curve (2 degrees ahead of 0 seems best so far)

No obvious change in performance whether car is hot or cold. Any thoughts on this issue? One theory is bad fuel filter, another is a vacuum leak somewhere. I figured I'd consult the accumulated wisdom of y'all before I start more serious operations. I didn't find any thread on this when searching, but my US terminology when it comes to engines isn't that great... Maybe there's a proper term for this behavior, but I don't know it. Thanks in advance from cold Sweden!

[dalebwilson]

Your combustion chamber is burning lean. Too much air or not enough fuel. Make sure the fuel sock in the tank is replaced as well as the fuel filter. Measuring your fuel pressure would be an easy thing to do as well as cranking your engine over with your fuel line disconnected and emptying into a can. Always keep a fire extinguisher close when diagnosing fuel related issues.

[121]

Thanks! That sounds like a good place to start. "Fuel sock" - is this some kind of filter device also? Do you know what the pressure is supposed to be? I haven't managed to get a service manual for this little ride yet. Thanks once again!

[navdoc101]

Your English/American seems pretty good , better than my Swedish.
With that "y'all" you would fit in down south.

[121]

Thanks navdoc101 :-) My "media & US entertainment" English is pretty decent I guess :-) It's my engine terminology I have to nail, as I read this eminent forum I realize I have to learn a lot in that department. One step at a time!

[Icedawg]

It certainly could be the fuel filter, I would check that first before the other stuff. You should be able to blow through it easily.

[drddan]

See this thread - Post #6

Carby rubber fuel line can collapse under pressure from getting soft with age

http://www.fordfestiva.com/forums/sh...I-like-my-car!

[Movin]

^^^ Yes!

[Fordverde]

Since you are in Sweden, is your hot air hose good? Don't know how cold can it gets in Sweden this time of the year, but i once lived in Holland years ago and i had a 86 VW Polo and my hot air hose had a big hole in it and my carb would freeze after driving it for a while and it chocked when driving but didn't affect the idle...

[dalebwilson]

Your combustion chamber is burning lean. Too much air or not enough fuel. Make sure the fuel sock in the tank is replaced as well as the fuel filter. Measuring your fuel pressure would be an easy thing to do as well as cranking your engine over with your fuel line disconnected and emptying into a can. Always keep a fire extinguisher close when diagnosing fuel related issues.

The fuel sock is the filter connected to the end of the fuel pump in the tank. If your engine is carbed and the fuel pump is operated by the camshaft then I am unsure if the fuel sock check is relevant. As others have mentioned, be sure and check the rubber fuel supply line that has a tendancy to collapse.

[Movin]

Checking the carby sock is still on the list. It is more common for this tube shaped round filter used only on the carby to slip up the metal line and plug the end on the metal line with the plastic end cap of the tube shaped sock-filter. A dent in the fuel tank can start havoc inside lol

[121]

Thanks all! Got some really good input from you, now the operation begins :-) New fuel filter & hoses ordered. I'll share some info once done. Cheers!

[drddan]

Please do one change at a time, so you can find what the problem is, and check back and let us know!

[121]

Will do :-)

[zoe60]

Bad O2 sensor can make the feedback carb run too lean and make it stumble on light acceleration.