<b>HEYLP!!</b>
I've an 89 (G) AX GT, & i have the following problem....
When on motorways at speeds of anything over 60mph, (Mainly between 70-80mph) the car seems to pull back.. its as if someone has a tow rope atached to the back and is puling on it, it lasts for about a second or two stops then come on again for another second or so, sometimes it happens sometimes , it doesnt...
Can anyone help?
Pleeeeeeeeeeeeeeeeeeeeeeeeeease[:D]
AX Problem, Hard to describe!
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jeremy
- Posts: 3959
- Joined: 20 Oct 2002, 16:00
- x 2
fuel starvation? - are all filters, pump etc working well?
Dirt in the carburrettor - has it got an economy system which leans off the mixture on steady running - if so is this working properly or does it try and feed off a smaller jet which is blocked? there are probably strange vacuum based devices which are supposed to operate these thing - are they tight, all hoses in good condition?
Jeremy
Dirt in the carburrettor - has it got an economy system which leans off the mixture on steady running - if so is this working properly or does it try and feed off a smaller jet which is blocked? there are probably strange vacuum based devices which are supposed to operate these thing - are they tight, all hoses in good condition?
Jeremy
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cheesesliceking
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bxbodger
- Posts: 1455
- Joined: 23 May 2003, 03:34
- x 1
Check your plugs, look at them very closely; I had a Fiat Uno which did this; one of the plugs had a split insulator nose, but it took ages to find as it looked o.k. at first glance; the car ran fine until it got to about 65-70 and then it would start to hold back, mainly when overtaking on the m-way.
I initially assumed it was a fuel fault as this is what it felt like, and it went on like this for ages as the plugs looked fine; I only spotted it when it got really bad.
Also, it would be wise to closely examine the rest of the ignition system for tracking; this can sometimes only manifest itself at speed when theres enough voltage/current to overcome resistance and track down the HT leads, distributor cap, coil housing, etc. give it a good clean and see if this makes a difference.
One final (and very easy) thing to check is the fuel tank breather: as you go faster you use fuel at a faster rate, and if the fuel tank isnt breathing properly, the petrol can't get out fast enough as the vacuum holds it back; hence fuel starvation. The next time it happens stop quickly, open the fuel filler and see if air rushes in as you release the vacuum.
Best of luck, intermittent faults are the worse!!!
I initially assumed it was a fuel fault as this is what it felt like, and it went on like this for ages as the plugs looked fine; I only spotted it when it got really bad.
Also, it would be wise to closely examine the rest of the ignition system for tracking; this can sometimes only manifest itself at speed when theres enough voltage/current to overcome resistance and track down the HT leads, distributor cap, coil housing, etc. give it a good clean and see if this makes a difference.
One final (and very easy) thing to check is the fuel tank breather: as you go faster you use fuel at a faster rate, and if the fuel tank isnt breathing properly, the petrol can't get out fast enough as the vacuum holds it back; hence fuel starvation. The next time it happens stop quickly, open the fuel filler and see if air rushes in as you release the vacuum.
Best of luck, intermittent faults are the worse!!!
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jeremy
- Posts: 3959
- Joined: 20 Oct 2002, 16:00
- x 2
If I'm correct your AX GT will have a solex or weber twin choke carburettor which will have a float chamber which will hold a small amount of fuel. So - cut off the fuel supply at idle and it will run for quite a while until the fuel is exhausted.
Imagine that the supply is partially blocked - it will idle ok, probably acelerate gently or for a short time and run at moderate speed.
What happens now2 depends on the degree of starvation. generally hard acceleration will produce the most dramatic results, the car starts to accelerate normally but as the float chamber gets exhausted it just dies, but as you lift off enough fuel arrives for it to run on a steady throttle.
I'm not suggesting your car has any add-on economy devices but modern carburettors have many bits and stages and often they are designed so that the mixture weakens while on a steady throttle for economy purposes. Many systems are used, fuel levels dropping or rising to cover holes, diaphragm actuators and many others. Even the twin choke design is there with economy in mind, the idea being that most of your motoring is on the primary (small) choke and the large one opens for maximum power.
I take it your secondary (large) choke is mechanically not vacuum operated? this could be a problem as well if vacuum - it may be shutting at the wrong time.
many years ago i say a test on a jensen interceptor SP. this had a 7 litre engine and the SP stood for Six Pack which was the number of chokes on the carburettors. Some of these were used for maximum power only and were vacuum operated. Apparently cornering at steady speed at 90 would affect the vacuum in the manifold and the extra chokes would open - result - right in the middle of the corner the car would try and do 120!
Do you know what carburettor is fitted to your AX GT/ I think its a weber but which model?
Jeremy
Imagine that the supply is partially blocked - it will idle ok, probably acelerate gently or for a short time and run at moderate speed.
What happens now2 depends on the degree of starvation. generally hard acceleration will produce the most dramatic results, the car starts to accelerate normally but as the float chamber gets exhausted it just dies, but as you lift off enough fuel arrives for it to run on a steady throttle.
I'm not suggesting your car has any add-on economy devices but modern carburettors have many bits and stages and often they are designed so that the mixture weakens while on a steady throttle for economy purposes. Many systems are used, fuel levels dropping or rising to cover holes, diaphragm actuators and many others. Even the twin choke design is there with economy in mind, the idea being that most of your motoring is on the primary (small) choke and the large one opens for maximum power.
I take it your secondary (large) choke is mechanically not vacuum operated? this could be a problem as well if vacuum - it may be shutting at the wrong time.
many years ago i say a test on a jensen interceptor SP. this had a 7 litre engine and the SP stood for Six Pack which was the number of chokes on the carburettors. Some of these were used for maximum power only and were vacuum operated. Apparently cornering at steady speed at 90 would affect the vacuum in the manifold and the extra chokes would open - result - right in the middle of the corner the car would try and do 120!
Do you know what carburettor is fitted to your AX GT/ I think its a weber but which model?
Jeremy
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cheesesliceking
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cheesesliceking