Hesitating when warmed up. Why?

I've had my red 1982 1.8gti for over a year and it has always started first time and the engine has been perfect…then I took it for the MOT and it had welding done and the fuel tank and some fuel pipe replaced.  Since then it has been ok for the first 2 minutes of driving, and then the engine hesitates when you apply the accelerator.
The point at which it hesitates gets lower and lower in the rev range until the point comes when you touch the accelerator and you do kangaroo style hops down the road while getting no drive from the engine.  When I have to stop, turn off the engine and then it does better for a little while, but then it kicks in again.
Does this sound like a blockage/muck in the fuel line or injectors or is the MOT work coincidence? Any ideas what is causing this?

Mot work could be coincidence, but if they didn't disconnect the battery they could have damaged the ignition module.  i'd say that's unlikely cos everyone knows to disconnect the battery!

Your description sounds very much like a problem I had which turned out to be a failing coil.  Try changing that first, if there are no better ideas here.  Make sure you get the correct coil as the wrong one will get hot and cause the same symtoms!

Wow, that's funny.

My cars in the garage, right now, poor damp start, hesitation and kangarooing.

I've gone for the electrics first.

Coil, HT leads, sparks, dizzy cap, rotor arm, condensor, points (you won't have those!)

?113

This is a lot cheaper and easier than starting on fuel supply, and a lot more likely to be causing your problems.

And without the points easy to do yourself as long as you get the HT leads back on in the same order you put them on!

Peter.

I'd agree that it's likely to be the coil failing as it warms up, but in the unlikely event that it's not:

Get the system pressure in the fuel metering head checked by a Bosch tuning agent (see Yellow Pages) - if the system pressure goes out of adjustment (too low) the car runs ok for a while as the Warm-up Regulator keeps it ok while the engine is cold but the pressure falls below what is acceptable as the temperature rises.

Unless something else is broken/knackered, it shouldn't cost too much to fix, as the pressure is adjusted by simply re-shimming a spring in the metering head, but this the changes required can only be measured with special Bosch tuning tools.

I'd definitely check the HT electrics first. In my experience hesitancy when driving is almost always down to electrics. If it cuts out completely that's when you start suspecting the fuel side of things.

Good luck!

Cheers,

Drew.

Hi your problem could be fuel starvation worth logging on to the old links and look at fuel problems / breather problems after you have checked the electrics

Chudd…..

I had this exact problem which turned out to be the coil breaking down when hot as Rich says. IMO it's cheaper and easier to check the ignition side before going to the fuel.

Personally,  I would check/replace fuel system parts as re-shimming the metering head should not be necessary.

Cheers
Rajan

Ok, picked up the car from garage yesterday.

It is actually like driving a different car!

It has new
HT leads, sparks, dizzy cap, rotor arm, condensor, points

And the timing was set.

They left the coil as it tested ok

The car now

Runs quieter
Runs smoother
runs cooler (I'm not kidding)
Smoother power take up (I thought the clutch was knackered)
No kangarooing (like when I decide I'm going to do 30 in 5th)
Starts without the engine even turning.

Why oh why did I leave this for so long!

Peter.